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7440-21-3

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7440-21-3 Usage

Description

Gay Lussac and Thenard in 1809 obtained very impure amorphous silicon by passing silicon tetrafluoride over heated potassium. Berzelius in 1823 prepared elemental silicon in high purity by the same method. He also obtained silicon by heating potassium fluosilicate with potassium metal. Deville produced crystalline silicon in 1854 by electrolysis of a molten mixture of impure sodium aluminum chloride containing 10% silicon and a small quantity of aluminum. Silicon is the second most abundant element on earth after oxygen. It occurs in nature combined with oxygen in various forms of silica and silicates. Silicates have complex structures consisting of SiO4 tetrahedral structural units incorporated to a number of metals. About 90% of the earth’s crust is made up of silica and naturally-occurring silicates. Silicon is never found in nature in free elemental form. Among all elements silicon forms the third largest number of compounds after hydrogen and carbon. There are well over 1,000 natural silicates including clay, mica, feldspar, granite, asbestos, and hornblende. Such natural silicates have structural units containing orthosilicates, SiO44– , pyrosilicates Si2O76– and other complex structural units, such as, (SiO3)n2n– that have hexagonal rings arranged in chains or pyroxenes (SiO32– )n and amphiboles, (Si4O116– )n in infinite chains. Such natural silicates include common minerals such as tremolite, Ca2Mg5(OH)2Si8O22; diopside, CaMg(SiO3)2; kaolin, H8Al4Si4O18; montmorillonite, H2Al2Si4O12; talc, Mg3[(OH)2 SiO10]; muscovite ( a colorless form of mica), H2KAl3(SiO4)3; hemimorphite, Zn4(OH)2Si2O7?H2O; beryl, Be3Al2Si6O18; zircon, ZrSiO4; benitoite, BaTiSi3O9; feldspars, KAlSi3O8; zeolites, Na2O?2Al2O3?5SiO2?5H2O; nephrite, Ca(Mg,Fe)3(SiO3)4; enstatite, (MgSiO3)n; serpentine, H4Mg3Si2O9; jadeite, NaAl(SiO3)2; topaz, Al2SiO4F2; and tourmaline, (H,Li,K,Na)9 Al3(BOH)2Si4O19. Many precious gemstones are silicate based. Such gems include beryl, emerald, aquamarine, morganite, topaz, tourmaline, zircon, amazon stone and moonstone.

Uses

Different sources of media describe the Uses of 7440-21-3 differently. You can refer to the following data:
1. Elemental silicon has some of the most important applications in this electronic age. One of the major applications is in computer chips. The single crystals of crystalline silicon are used for solid-state or semiconductor devices. Silicon of hyperpurity, doped with trace elements, such as boron, phosphorus, arsenic, and gallium is one of the best semiconductors. They are used in transistors, power rectifiers, diodes and solar cells. Silicon rectifiers are most efficient in converting a-c to d-c electricity. Hydrogenated amorphous silicon converts solar energy into electricity.
2. Silicon is usually available as electronic-grade, high-quality, high-purity single crystalline material in the form of wafers (round, surface-polished slices typically of 4–12 inches in diameter and a few hundreds of micrometers to millimeters in thickness). The biggest advantage of using silicon for microfluidic applications is the availability of a mature processing technology inherited from the microelectronics IC industry as well as the possibility of defining very small structures that can be cointegrated with the electronics on the same chip. Some of the disadvantages of using silicon as a structural material are linked to the polar nature of the silicon crystal resulting in undesirable adsorption of molecules in microfluidic systems. Furthermore, the higher cost of silicon as substrate material without any specific advantages from microfluidic systems standpoint makes it less attractive as a substrate material unless integration of on-chip electronic circuits is a strong requirement for the particular microsystem design. The typical cost of an average quality silicon substrate is about 0.25 U.S. cents/cm2.
3. In making silanes and silicones, the Si-C bond being about as strong as a C-C bond. In the manufacture of transistors, silicon diodes and similar semiconductors. For making alloys such as ferrosilicon, silicon bronze, silicon copper. As a reducing agent like aluminum in high tempereture reactions.
4. silicone (volatile) is used in face creams to increase the product’s protection capabilities against water evaporation from the skin. Silicone polyethers are mainly used in water-based skin care formulations and give improved softness, gloss, and feel. Silicones have been used in cosmetics for more than 30 years. They are minerals able to repel water. Silicones present formulation problems because of poor compatibility with cosmetic oils and emollients. Silicones are not irritating.
5. Silicon’s tetravalent pyramid crystalline structure, similar to tetravalent carbon, results ina great variety of compounds with many practical uses. Crystals of silicon that have beencontaminated with impurities (arsenic or boron) are used as semiconductors in the computerand electronics industries. Silicon semiconductors made possible the invention of transistorsat the Bell Labs in 1947. Transistors use layers of crystals that regulate the flow of electric current.Over the past half-century, transistors have replaced the vacuum tubes in radios, TVs,and other electronic equipment that reduces both the devices’ size and the heat produced bythe electronic devices.Silicon can be used to make solar cells to provide electricity for light-activated calculatorsand satellites. It also has the ability to convert sunlight into electricity.When mixed with sodium carbonate (soda ash) and calcium carbonate (powdered limestone)and heated until the mixture melts, silica (sand) forms glass when cooled. Glass ofall types has near limitless uses. One example is Pyrex, which is a special heat-resistant glassthat is manufactured by adding boron oxide to the standard mixture of silica, soda ash, andlimestone. Special glass used to make eyewear adds potassium oxide to the above standardmixture.Silicon is also useful as an alloy when mixed with iron, steel, copper, aluminum, andbronze. When combined with steel, it makes excellent springs for all types of uses, includingautomobiles.When silicon is mixed with some organic compounds, long molecular chains known assilicone polymers are formed. By altering the types of organic substances to these long siliconepolymer molecules, a great variety of substances can be manufactured with varied physicalproperties. Silicones are produced in liquid, semisolid, and solid forms. Silicones may berubbery, elastic, slippery, soft, hard, or gel-like. Silicone in its various forms has many commercialand industrial uses. Some examples are surgical/reconstructive implants, toys, SillyPutty, lubricants, coatings, water repellents for clothing, adhesives, cosmetics, waxes, sealants,and electrical insulation.

Production Methods

Elemental silicon is produced commercially by heating silica with carbon (coke) in an electric furnace using carbon electrodes: SILICON 819SiO2 + C → Si + CO2 The product obtained is about 96 to 98% purity. Repeated leaching forms about 99.7% purified product. Alternatively, lower grade silicon is converted to its halide or halosilane, which is then reduced with a high purity reducing agent. Hyperpure silicon for semiconductor applications can be made by several methods. Such processes include reduction of silicon tetrachloride with highly pure zinc: SiCl4 + 2Zn → Si + 2ZnCl2 or by reducing trichlorosilane with hydrogen at 1,150°C using a silicon filament on which deposition of silicon occurs: SiHCl3 + H2 → Si + 3HCl or by heating silane or silicon tetraiodide to elevated temperatures: SiH4 → Si + 2H2 SiI4 → Si + 2I2 or by reducing silicon tetrafluoride with sodium: SiF4 + 4Na → Si + 4 NaF Several processes are known to achieve growth of single crystals of silicon for semiconductors. One such method developed in 1918 is known as Czocharlski process or Teal-Little method. The process involves dipping a single crystal “seed” into molten silicon held at the melting point. The seed is properly oriented by rotation and the molten silicon is allowed to freeze gradually over it and the seed is slowly withdrawn. The growth rate is controlled by melt temperature and heat losses from the crystal. Growth rates are usually in the range of 2.5 cm/hour but can vary with diameter. Crystals of varying sizes have been produced by this method. The common sizes of crystals usually range between 75 to 125 mm in diameter and about 100 cm long. Pure quartz crucibles or silicon pedestals are employed to carry out single crystal’s growth.

Chemical Properties

Different sources of media describe the Chemical Properties of 7440-21-3 differently. You can refer to the following data:
1. grey lustrous solid or grey powder
2. Silicon is a nonmetallic element which is known as silicon metal. Not occur freely in nature, but is found in silicon dioxide (silica) and in various silicates. It is a steel-gray crystalline solid or a black-brown amorphous material.

Physical properties

Silicon does not occur free in nature, but is found in most rocks, sand, and clay. Siliconis electropositive, so it acts like a metalloid or semiconductor. In some ways silicon resemblesmetals as well as nonmetals. In some special compounds called polymers, silicon will act inconjunction with oxygen. In these special cases it is acting like a nonmetal. There are two allotropes of silicon. One is a powdery brown amorphous substance bestknown as sand (silicon dioxide). The other allotrope is crystalline with a metallic grayishluster best known as a semiconductor in the electronics industry. Individual crystals of siliconare grown through a method known as the Czochralski process. The crystallized siliconis enhanced by “doping” the crystals (adding some impurities) with other elements such asboron, gallium, germanium, phosphorus, or arsenic, making them particularly useful in themanufacture of solid-state microchips in electronic devices. The melting point of silicon is 1,420°C, its boiling point is 3,265°C, and its density is2.33 g/cm3.

Isotopes

There are 21 isotopes of silicon, three of which are stable. The isotope Si-28makes up 92.23% of the element’s natural abundance in the Earth’s crust, Si-29 constitutes4.683% of all silicon found in nature, and the natural abundance of Si-30 ismerely 3.087% of the stable silicon isotopes found in the Earth’s crust.

Origin of Name

Silicon was named after the Latin word silex, which means “flint.”

Occurrence

Silicon, in the form of silicon dioxide (SiO2), is the most abundant compound in theEarth’s crust. As an element, silicon is second to oxygen in its concentration on Earth, yet it is only the seventh most abundant in the entire universe. Even so, silicon is used as the standard(Si = 1) to estimate the abundances of all other elements in the universe. For example, hydrogenequals 40,000 times the amount of silicon in the cosmos. Hydrogen is the most abundantof all elements in the universe, and carbon is just three and half times as abundant as siliconin the entire universe. On Earth silicon accounts for 28% of the crust, oxygen makes up 47%of the crust, and much of the rest of the crust is composed of aluminum.It is believed that silicon is the product of the cosmic nuclear reaction in which alpha particleswere absorbed at a temperature of 109 Kelvin into the nuclei of carbon-12, oxygen-16,and neon-20. Pure elemental silicon is much too reactive to be found free in nature, but it doesform many compounds on Earth, mainly oxides as crystals (quartz, cristobalite, and tridymite)and amorphous minerals (agate, opal, and chalcedony). Elemental silicon is produced byreducing silica (SiO2) in a high-temperature electric furnace, using coke as the reducing agent.It is then refined. Silicon crystals used in electronic devices are “grown” by removing startercrystals from a batch of melted silicon.

Characteristics

The characteristics of silicon in some ways resemble those of the element germanium,which is located just below it in the carbon group.Flint is the noncrystalline form of silicon and has been known to humans since prehistorictimes. When struck with a sharp blow, flint would flake off sharp-edged chips that were thenused as cutting tools and weapons.In addition to silica (silicon dioxide SiO2), the crystal form of silicon is found in severalsemiprecious gemstones, including amethyst, opal, agate, and jasper, as well as quartz of varyingcolors. A characteristic of quartz is its piezoelectric effect. This effect occurs when thequartz crystal is compressed, producing a weak electrical charge. Just the opposite occurs whenelectric vibrations are fed to the crystal. These vibrations are then duplicated in the crystal.Quartz crystals are excellent timekeeping devices because of this particular characteristic.

History

Davy in 1800 thought silica to be a compound and not an element; later in 1811, Gay Lussac and Thenard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride. Berzelius, generally credited with the discovery, in 1824 succeeded in preparing amorphous silicon by the same general method as used earlier, but he purified the product by removing the fluosilicates by repeated washings. Deville in 1854 first prepared crystalline silicon, the second allotropic form of the element. Silicon is present in the sun and stars and is a principal component of a class of meteorites known as “aerolites.” It is also a component of tektites, a natural glass of uncertain origin. Natural silicon contains three isotopes. Twenty-four other radioactive isotopes are recognized. Silicon makes up 25.7% of the Earth’s crust, by weight, and is the second most abundant element, being exceeded only by oxygen. Silicon is not found free in nature, but occurs chiefly as the oxide and as silicates. Sand, quartz, rock crystal, amethyst, agate, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, hornblende, asbestos, feldspar, clay mica, etc. are but a few of the numerous silicate minerals. Silicon is prepared commercially by heating silica and carbon in an electric furnace, using carbon electrodes. Several other methods can be used for preparing the element. Amorphous silicon can be prepared as a brown powder, which can be easily melted or vaporized. Crystalline silicon has a metallic luster and grayish color. The Czochralski process is commonly used to produce single crystals of silicon used for solid-state or semiconductor devices. Hyperpure silicon can be prepared by the thermal decomposition of ultra-pure trichlorosilane in a hydrogen atmosphere, and by a vacuum float zone process. This product can be doped with boron, gallium, phosphorus, or arsenic to produce silicon for use in transistors, solar cells, rectifiers, and other solid-state devices that are used extensively in the electronics and space-age industries. Hydrogenated amorphous silicon has shown promise in producing economical cells for converting solar energy into electricity. Silicon is a relatively inert element, but it is attacked by halogens and dilute alkali. Most acids, except hydrofluoric, do not affect it. Silicones are important products of silicon. They may be prepared by hydrolyzing a silicon organic chloride, such as dimethyl silicon chloride. Hydrolysis and condensation of various substituted chlorosilanes can be used to produce a very great number of polymeric products, or silicones, ranging from liquids to hard, glasslike solids with many useful properties. Elemental silicon transmits more than 95% of all wavelengths of infrared, from 1.3 to 6.7 μm. Silicon is one of man’s most useful elements. In the form of sand and clay it is used to make concrete and brick; it is a useful refractory material for high-temperature work, and in the form of silicates it is used in making enamels, pottery, etc. Silica, as sand, is a principal ingredient of glass, one of the most inexpensive of materials with excellent mechanical, optical, thermal, and electrical properties. Glass can be made in a very great variety of shapes, and is used as containers, window glass, insulators, and thousands of other uses. Silicon tetrachloride can be used to iridize glass. Silicon is important in plant and animal life. Diatoms in both fresh and salt water extract silica from the water to build up their cell walls. Silica is present in ashes of plants and in the human skeleton. Silicon is an important ingredient in steel; silicon carbide is one of the most important abrasives and has been used in lasers to produce coherent light of 4560 ?. A remarkable material, first discovered in 1930, is Aerogel, which is now used by NASA in their space missions to collect cometary and interplanet dust. Aerogel is a highly insulative material that has the lowest density of any known solid. One form of Aerogel is 99.9% air and 0.1% SiO2 by volume. It is 1000 times less dense than glass. It has been called “blue smoke” or “solid smoke.” A block of Aerogel as large as a person may weigh less than a pound and yet support the weight of 1000 lbs (455 kg). This material is expected to trap cometary particles traveling at speeds of 32 km/sec. Aerogel is said to be non-toxic and non-inflammable. It has high thermal insulating qualities that could be used in home insulation. Its light weight may have aircraft applications. Regular grade silicon (99.5%) costs about $160/kg. Silicon (99.9999%) pure costs about $200/kg; hyperpure silicon is available at a higher cost. Miners, stonecutters, and other engaged in work where siliceous dust is breathed in large quantities often develop a serious lung disease known as silicosis.

Definition

Different sources of media describe the Definition of 7440-21-3 differently. You can refer to the following data:
1. Nonmetallic element Atomic number 14, group IVA of the periodic table, aw 28.086, valence = 4, three stable isotopes. It is the second most abundant ele- ment (25% of the earth’s crust) and is the most important semiconducting element; it can form more co
2. silicon: Symbol Si. A metalloid element belonging to group 14 (formerlyIVB) of the periodic table; a.n.14; r.a.m. 28.086; r.d. 2.33; m.p.1410°C; b.p. 2355°C. Silicon is thesecond most abundant element inthe earth’s crust (25.7% by weight) occurring in various forms of silicon(IV)oxide (e.g. quartz) and in silicateminerals. The element is extractedby reducing the oxide with carbon inan electric furnace and is used extensivelyfor its semiconductor properties.It has a diamond-like crystalstructure; an amorphous form alsoexists. Chemically, silicon is less reactivethan carbon. The element combineswith oxygen at red heat and isalso dissolved by molten alkali. Thereis a large number of organosiliconcompounds (e.g. siloxanes) althoughsilicon does not form the range ofsilicon–hydrogen compounds andderivatives that carbon does (seesilane). The element was identifiedby Antoine Lavoisier in 1787 andfirst isolated in 1823 by J?ns Berzelius.

General Description

A dark brown powder. Insoluble in water and denser than water. Burns readily when exposed to heat or flames, and may be difficult to extinguish. Water may not be effective in extinguishing flames. Used to make computer microchips.

Air & Water Reactions

Highly flammable. Insoluble in water. A significant dust explosion hazard.

Reactivity Profile

Silicon is a reducing agent. Ignites in fluorine gas at ordinary temperatures [Mellor 2:11-13 1946-47]. Burns spontaneously in gaseous chlorine. A mixture of silicon, aluminum, and lead oxide explodes when heated [Mellor 7:657 1946-47]. When heated with an alkali carbonate, a vigorous reaction attended by incandescence occurs [Mellor 6:164 1946-47]. Reacts violently with silver fluoride [Mellor 3:389 1946-47]. Reacts with sodium-potassium alloy to form sodium silicide, which is spontaneously flammable in air [Mellor 2 Supp. 2:564 1961].

Hazard

The dust of silicon oxide (silicate) can burn or explode and is very harmful if inhaled.Continued exposure to silica dust causes silicosis, a form of pneumonia.The hydrides of silicon (silicon plus hydrogen) are extremely volatile and spontaneouslyburst into flames in air at room temperatures. They must be kept in special vacuum chambers.Over the past several decades, there has been some concern over the potential hazards andsafety of the cosmetic use of silicone body implants—breast implants, in particular. Severalmanufactures have been sued over the failure of the implants, and the federal government (FDA) withdrew its approval for their use. Congressional hearings with manufacturers in2005 produced new information that has reversed the FDA’s ban on their use—but only withcertain manufacturers of implants. The debate continues.

Health Hazard

Oxides from metallic fires are a severe health hazard. Inhalation or contact with substance or decomposition products may cause severe injury or death. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause pollution.

Fire Hazard

May react violently or explosively on contact with water. Some are transported in flammable liquids. May be ignited by friction, heat, sparks or flames. Some of these materials will burn with intense heat. Dusts or fumes may form explosive mixtures in air. Containers may explode when heated. May re-ignite after fire is extinguished.

Flammability and Explosibility

Nonflammable

Agricultural Uses

Some plants need silicon (Si) in addition to micro and macro nutrients. It is one of the most abundant elements absorbed by plants. Silicon belongs to Group 14 (formerly IVB) of the Periodic Table. It is an essential trace element for the normal growth of higher animals, as it is involved in the formation of bones and cartilages. Crops grown in the absence of soluble silica are more prone to mildews than those provided with soluble silica. Rice, cucumber, gherkin and barley require silicon. Silicon improves the growth of sugar cane. Silicon corrects soil toxicities arising from the presence of excessive quantities of Mn, Fe and active Al. The oxidizing power of rice roots and their tolerance to the high level of iron and manganese are attributed to silicon nutrition. In a field trial, when parts of a rice crop had a silica to nitrogen ratio of 11:2, 10 tons/ha of extra rice was produced. Silicon helps to (a) maintain the erectness of rice leaves, (b) increase resistance to insect pests, (c) improve photosynthesis, (d) increase the number of stems, and (e) improve the fresh as well as dry weights of rice plants. If silica is withheld during the reproductive period, the number of spikelets per panicle and the ripened grain percentage decreases. Silicon contributes to the structure of cell wall, thus (a) making the cell wall more immune to diseases, (b) improving the stalk strength, and (c) increasing the resistance to lodging. Rice and sugar cane respond favorably to silicon fertilizers. Enzyme-silicon complexes formed in sugar cane act as protectors or regulators of photosynthesis and enzyme activity. By suppressing the invertase activity in sugar cane, silicon increases sugar production. Silicon and oxygen occupy 75% of the earth's crust, of which silicon alone is 27.7%. Silica, which occurs to the extent of 60 to 80% as insoluble quartz silica, is in the form of mono-silicic acid [Si(OH)4], the availability of which increases with increasing soil pH and temperature. Roughly, 130 ppm silicon (SO2) is the critical limit of the available silicon in air-dry soil for maximizing wetland rice yield; the critical limit is raised by adding silicon (as SiO2). Silicon uptake by plants differ with plant species. Gramineae contains 10 to 20 times more silicon than that normally found in legumes and dicotyledons. Paddy contains 4.6 to 7.0% of silicon in the straw. Oxides of iron and aluminum, liming, flooding and nutrient supply influence silicon-uptake; high soil-water content increases the uptake in rice, barley, oats, sorghum and sugar cane. The quantity of silica fertilizer to be added to the soil is guided by the ratio of the available silica to organic matter, which if less than 100, warrants the use of fertilizer; if the ratio is more than 100, it calls for the addition of organic matter; if less than 50, it indicates that the soil is suffering from silicon shortage. For a silicondeficient area, the addition of 2 todha of silica fertilizer is recommended. Freckling, which is a necrotic leaf spot condition, is a symptom of low levels of silicon in a sugar cane plant that receives direct sunlight, the ultraviolet (W) radiation in sunlight being the causative agent. Sufficient quantities of silicon in a sugar cane plant filters out harmful UV radiation. Major silica fertilizers include calcium silicate slag, calcium silicate and sodium meta-silicate. 1.5 to 2.0 tons of silicate slag per hectare usually provides sufficient silicon for rice crops produced in low-silicon soils. Silicate fertilizers serve as a source of silicon and a liming material in acid soils. Slags from the steel industry, ground basic-slag (containing varying quantities of Al, Ca, Fe, Mn, Mg and Si), and wollastonite (Ca-Mg silicate) are all silicate fertilizers. Sodium silicate increases the crop yield in phosphatedeficient soils, possibly because silicates help increase the assimilation of phosphoric acid by the plant and not the soil. However, according to some, silicate increases the amount of available soil phosphate. Heavy applications of nitrogen make the rice plant more susceptible to fungal attack because of the decreased silicon concentration in the straw.

Industrial uses

Silicon is, after oxygen, the second most abundant element in the earth s crust. It occurs in a range of minerals and sand (SiO2, quartz). Silicon can be extracted from silicates or sand by reducing SiO2 with coke at high temperatures at around 3000°C.Silicon is used in a wide variety of applications. In nature, silicon does not exist as the pure metal and most commonly occurs in silica (including sand) and silicates. Silicon dioxide, also known as silica, is a hard substance with a high melting temperature and clearly very different from carbon dioxide. Molten silica can be used to make glass, an extremely useful material, which is resistant to attack by most chemicals except fluorine, hydrofluoric acid and strong alkalis. Silicon atoms can also be found in the class of compounds called silicones. Pure silicon metal is used in semiconductors, the basis of all electronic devices, and is most well known for its application in solar panels and computer chips.

Safety Profile

A nuisance dust. Moderately toxic by ingestion. An eye irritant. Does not occur freely in nature, but is found as sdicon dioxide (sdtca) and as various shcates. Elemental Si is flammable when exposed to flame or by chemical reaction with oxidlzers. Violent reactions with alkali carbonates, oxidants, (A1 + PbO), Ca, Cs2C2, Cl2, CoF2, F2, IFs, MnF3, Rb2C2, FNO, AgF, NaK alloy. When heated it will react with water or steam to produce H2; can react with oxidizing materials. See also various silica entries, SILICATES, and POWDERED METALS.

Potential Exposure

Silicon may be used in the manufacture of silanes, silicon tetrachloride, ferrosilicon, silicones. It is used in purified elemental form in transistors and photovoltaic cells.

Shipping

UN1346 Silicon powder, amorphous requires, Hazard Class: 4.1; Labels: 4.1-Flammable solid.

Incompatibilities

Dust or powder may form explosive mixture with air. A strong reducing agent. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, calcium, carbonates, chlorine, fluorine, oxidizers, cesium carbide; alkaline carbonates.

Check Digit Verification of cas no

The CAS Registry Mumber 7440-21-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,4,4 and 0 respectively; the second part has 2 digits, 2 and 1 respectively.
Calculate Digit Verification of CAS Registry Number 7440-21:
(6*7)+(5*4)+(4*4)+(3*0)+(2*2)+(1*1)=83
83 % 10 = 3
So 7440-21-3 is a valid CAS Registry Number.
InChI:InChI=1/Si

7440-21-3 Well-known Company Product Price

  • Brand
  • (Code)Product description
  • CAS number
  • Packaging
  • Price
  • Detail
  • Alfa Aesar

  • (43926)  Silicon slugs, 9.5mm (0.375in) dia x 9.5mm (0.375in) length, 99.9999% (metals basis)   

  • 7440-21-3

  • 25g

  • 2976.0CNY

  • Detail
  • Alfa Aesar

  • (43926)  Silicon slugs, 9.5mm (0.375in) dia x 9.5mm (0.375in) length, 99.9999% (metals basis)   

  • 7440-21-3

  • 100g

  • 11902.0CNY

  • Detail
  • Alfa Aesar

  • (40890)  Silicon sputtering target, 50.8mm (2.0in) dia x 3.18mm (0.125in) thick, 99.999% (metals basis)   

  • 7440-21-3

  • 1each

  • 2185.0CNY

  • Detail
  • Alfa Aesar

  • (40891)  Silicon sputtering target, 50.8mm (2.0in) dia x 6.35mm (0.250in) thick, 99.999% (metals basis)   

  • 7440-21-3

  • 1each

  • 4556.0CNY

  • Detail
  • Alfa Aesar

  • (40893)  Silicon sputtering target, 76.2mm (3.0in) dia x 6.35mm (0.250in) thick, 99.999% (metals basis)   

  • 7440-21-3

  • 1each

  • 4302.0CNY

  • Detail
  • Alfa Aesar

  • (45380)  Silicon Optical Window, 25.4mm (1.0in) dia x 1mm (0.04in) thick   

  • 7440-21-3

  • 1each

  • 2067.0CNY

  • Detail
  • Alfa Aesar

  • (45381)  Silicon Optical Window, 25.4mm (1.0in) dia x 2mm (0.08in) thick   

  • 7440-21-3

  • 1each

  • 1744.0CNY

  • Detail
  • Alfa Aesar

  • (35662)  Silicon powder, crystalline, -325 mesh, 99.999% (metals basis)   

  • 7440-21-3

  • 1g

  • 117.0CNY

  • Detail
  • Alfa Aesar

  • (35662)  Silicon powder, crystalline, -325 mesh, 99.999% (metals basis)   

  • 7440-21-3

  • 10g

  • 435.0CNY

  • Detail
  • Alfa Aesar

  • (35662)  Silicon powder, crystalline, -325 mesh, 99.999% (metals basis)   

  • 7440-21-3

  • 50g

  • 789.0CNY

  • Detail
  • Alfa Aesar

  • (36212)  Silicon powder, crystalline, -100+325 mesh, 99.999% (metals basis)   

  • 7440-21-3

  • 10g

  • 705.0CNY

  • Detail
  • Alfa Aesar

  • (36212)  Silicon powder, crystalline, -100+325 mesh, 99.999% (metals basis)   

  • 7440-21-3

  • 50g

  • 1547.0CNY

  • Detail

7440-21-3SDS

SAFETY DATA SHEETS

According to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - Sixth revised edition

Version: 1.0

Creation Date: Aug 16, 2017

Revision Date: Aug 16, 2017

1.Identification

1.1 GHS Product identifier

Product name silicon atom

1.2 Other means of identification

Product number -
Other names porous silicon

1.3 Recommended use of the chemical and restrictions on use

Identified uses For industry use only.
Uses advised against no data available

1.4 Supplier's details

1.5 Emergency phone number

Emergency phone number -
Service hours Monday to Friday, 9am-5pm (Standard time zone: UTC/GMT +8 hours).

More Details:7440-21-3 SDS

7440-21-3Synthetic route

Dichlorosilane
4109-96-0

Dichlorosilane

silicon
7440-21-3

silicon

Conditions
ConditionsYield
Prepd. by laser chemical vapor pptn. at atmospheric pressure.;100%
In neat (no solvent) chemical vapor deposition with a mixt. of SiH2Cl2 and H2;
With hydrogen chemical vapor deposition (hot-wall reactor, basic pressure 10 or 76 Torr, 1223 K);
trichlorosilane
10025-78-2

trichlorosilane

silicon
7440-21-3

silicon

Conditions
ConditionsYield
Stage #1: trichlorosilane under 3.75038 Torr; for 6h; Pulsed microwave radiation (25-50W);
Stage #2: With hydrogen at 900℃;
96.7%
With hydrogen chemical vapor deposition (8% SiHCl3 in H2, 1100°C);
With hydrogen chemical vapor deposition (hot-wall reactor, basic pressure 10 or 76 Torr, 1223 K);
Conditions
ConditionsYield
With magnesium oxide; magnesium In neat (no solvent) mixt. of 180 parts SiO2, 144 parts Mg and 81 parts MgO, covered with a layer of Mg in a warmed up crucible, heating at red heat in a electric furnace, begin of the react. after 2-3 min. with strong glowing, best yields with a SiO2 grainsize of 0.14mm;; treatment of the reactionproduct with HCl, H2SO4 and HF one after another, Si powder of 99.09-99.60% purity;;92.7%
With Mg; MgO In neat (no solvent) mixt. of 180 parts SiO2, 144 parts Mg and 81 parts MgO, covered with a layer of Mg in a warmed up crucible, heating at red heat in a electric furnace, begin of the react. after 2-3 min. with strong glowing, best yields with a SiO2 grainsize of 0.14mm;; treatment of the reactionproduct with HCl, H2SO4 and HF one after another, Si powder of 99.09-99.60% purity;;92.7%
With magnesium Inert atmosphere; Schlenk technique;46.7%
tetrachlorosilane
10026-04-7, 53609-55-5

tetrachlorosilane

silicon
7440-21-3

silicon

Conditions
ConditionsYield
With hydrogen at 700℃; under 15.0015 Torr; Product distribution / selectivity; Microwave radiation (200W);60%
Product distribution / selectivity;
With KBr or KI In neat (no solvent) byproducts: KCl, Br; uncomplete reaction of SiCl4 with KBr or KI at 300-400 °C;;
methane
34557-54-5

methane

monosilane
7440-21-3

monosilane

silicon carbide

silicon carbide

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
With H2 In neat (no solvent) chemical vapour deposition of CH4 (4.0 mol%), H2 and SiH4 (2.0 mol%) gases in reaction-sintered SiC tube within mullite tube in resistance furnace, total gas flow rate 2.7E-5 m**3/sec, total gas pressure 0.1 MPa, 1623K; transmission electron microscopy, pycnometry, IR spectroscopy, X-ray diffractometry;A 23%
B n/a
With H2 In neat (no solvent) chemical vapour deposition of CH4 (7.2 mol%), H2 and SiH4 (3.6 mol%) gases in reaction-sintered SiC tube within mullite tube in resistance furnace, total gas flow rate 2.7E-5 m**3/sec, total gas pressure 0.1 MPa, 1623K; transmission electron microscopy, pycnometry, IR spectroscopy, X-ray diffractometry;A 19%
B n/a
With H2 In neat (no solvent) chemical vapour deposition of CH4 (4.0 mol%), H2 and SiH4 (2.0 mol%) gases in reaction-sintered SiC tube within mullite tube in resistance furnace, total gas flow rate 2.7E-5 m**3/sec, total gas pressure 0.1 MPa, 1573K; transmission electron microscopy, pycnometry, IR spectroscopy, X-ray diffractometry;A 14%
B n/a
sodium metasilicate nonahydrate

sodium metasilicate nonahydrate

magnesium
7439-95-4

magnesium

A

magnesium hydroxide

magnesium hydroxide

B

hydrogen
1333-74-0

hydrogen

C

magnesium oxide

magnesium oxide

D

sodium hydroxide
1310-73-2

sodium hydroxide

E

silicon
7440-21-3

silicon

Conditions
ConditionsYield
at 200℃; under 116262 Torr; for 10h; Temperature; Autoclave;A n/a
B n/a
C n/a
D n/a
E 10%
monosilane
7440-21-3

monosilane

A

trisilane
7783-26-8

trisilane

B

disilane

disilane

C

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In gaseous matrix byproducts: H2; other Radiation; photolysis of pure SiH4 or a 37% mixture with N2 or Ar or H2 or He (total pressure = 80 Torr) in stainless steel cell by cw CO2 laser (945.98 cm**-1=IR), strong luminescence accompanies the react.; traces of higher silanes (gases) and solid hydrogenated silicon also present, H2 or He inhibit the react.;A 0%
B 2%
C n/a
molybdenium disilicate

molybdenium disilicate

A

pentamolybdenum trisilicide

pentamolybdenum trisilicide

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In neat (no solvent) evapn. in N2-plasma-flow; detd. by X-ray diffraction;A 1%
B 1%
tetrachlorosilane
10026-04-7, 53609-55-5

tetrachlorosilane

A

silicon, oxidized

silicon, oxidized

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
Product distribution / selectivity;
monosilane
7440-21-3

monosilane

silicon
7440-21-3

silicon

Conditions
ConditionsYield
at 1000℃; under 810.081 Torr; Gas phase (argon/H2 or argon alone);
With diborane at 1000℃; under 810.081 Torr; Gas phase (H2/argon);
With tri-tert-butyl phosphine at 1000℃; under 810.081 Torr; Gas phase (H2/argon);
calcium silicide

calcium silicide

ammonium chloride

ammonium chloride

A

silicon nitride

silicon nitride

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In neat (no solvent) High Pressure; excessive NH4Cl and CaSi2 heated at 600 °C for 10 h in autoclave;
silicon carbide

silicon carbide

aluminum oxide
1333-84-2, 1344-28-1

aluminum oxide

A

silicon monoxide

silicon monoxide

mullite

mullite

C

carbon monoxide
201230-82-2

carbon monoxide

D

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In melt mixing of Al2O3 and SiO2 in weight ratio 69:31 in C2H5OH using a ball mill for 1 h, drying at 75°C in an oven, infiltration into SiC preform in temp. range from 1830°C to 1850°C in BN crucible with a lid for 10 min; gas evolution, identification by XRD;
aluminum oxide
1333-84-2, 1344-28-1

aluminum oxide

silica

silica

silicon
7440-21-3

silicon

Conditions
ConditionsYield
With silicon In neat (no solvent) reaction in a Rh crucible in a high vacuum at 1300-1400 °C, small amount of Si by use of a small exceed of Si after vaporization of the other reaction educts, further product (beside Si): a glassy, amorphous yellow-brown black substance;;
With Si In neat (no solvent) reaction in a Rh crucible in a high vacuum at 1300-1400 °C, small amount of Si by use of a small exceed of Si after vaporization of the other reaction educts, further product (beside Si): a glassy, amorphous yellow-brown black substance;;
trisilane
7783-26-8

trisilane

silicon
7440-21-3

silicon

Conditions
ConditionsYield
cobalt In toluene High Pressure; Ti reactor sealed in N2 filled glove box connected to HPLC pump, filled O2 free toluene; Si wafer placed in; 3.4 MPa, heated to 350 or 400 or 450°C; trisilane in toluene injected; seed nanocrystals of Co; 10.3MPa, 10 min; reactor immersed in ice water, cooled to room temp.; substrate (Si wafer) removed; SEM; TEM;;
silicon doted with sulfur

silicon doted with sulfur

bromine
7726-95-6

bromine

silicon
7440-21-3

silicon

Conditions
ConditionsYield
gold mixt. heating in sealed tube, according to A. V. Sandulova et al., Patent USSR No. 160829, prior. 06.07.1962, Bull. Izobretenii i Otkritii, No. 5 (1964): R. S. Wagner et al., J. appl. Phys. 35, 9 (1964) 2993;
disiloxane
107-46-0

disiloxane

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In neat (no solvent) incineration of disiloxane;; formation of amorphous Si;;
With air In neat (no solvent) combustion in a flame with formation of a white smoke;;
potassium chromate

potassium chromate

potassium hexafluorosilicate

potassium hexafluorosilicate

A

chromium disilicide

chromium disilicide

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
With potassium fluoride; potassium chloride In melt Electrochem. Process; anode: graphite crucible with melt (KCl, 25% KF, 1% K2SiF6, K2CrO4), cathode: W rod, reference electrode: Pt wire, 900°C, U=3-4 V, 0.5 or1.0% K2CrO4 (t=60 min); product removing with cathode, mixture crushing, leaching (water and aq.H2SO4 at 50-60°C), solid residue sepn. and drying (100-105.degre e.C);
potassium chromate

potassium chromate

potassium hexafluorosilicate

potassium hexafluorosilicate

A

chromium silicide

chromium silicide

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
With potassium fluoride; potassium chloride In melt Electrochem. Process; anode: graphite crucible with melt (KCl, 25% KF, 1% K2SiF6, K2CrO4), cathode: W rod, reference electrode: Pt wire, 900°C, U=3-4 V, 0.5% K2CrO4 (t=10 min) or 1.0% K2CrO4 (t=15 min); product removing with cathode, mixture crushing, leaching (water and aq.H2SO4 at 50-60°C), solid residue sepn. and drying (100-105.degre e.C);
sodium silicate

sodium silicate

sodium fluoride

sodium fluoride

A

sodium
7440-23-5

sodium

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In melt Electrolysis;
tetrachlorosilane
10026-04-7, 53609-55-5

tetrachlorosilane

potassium bromide
7558-02-3

potassium bromide

A

bromine
7726-95-6

bromine

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
byproducts: KCl; heated for some days at 400 °C in a closed tube;
tetrachlorosilane
10026-04-7, 53609-55-5

tetrachlorosilane

potassium bromide
7558-02-3

potassium bromide

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In neat (no solvent) byproducts: KCl, Br2; slight reaction only on heating in a melting tube at 390-400 °C for a period of 75 hours;;
In neat (no solvent) byproducts: KCl, Br2; slight reaction only on heating in a melting tube at 390-400 °C for a period of 75 hours;;
silicon carbide

silicon carbide

A

silicon monoxide

silicon monoxide

B

pyrographite
7440-44-0

pyrographite

C

silicon
7440-21-3

silicon

Conditions
ConditionsYield
With carbon monoxide In neat (no solvent) Kinetics; in a hermetic furnace with a graphite heater in an atmosphere of CO; SiC is placed in graphite crucibles with lids and kept at 2270-2670 K for 900, 1800, 2700 and 3600 s; cooled samples are weighed and investigated by chem. anal. and IR-spectrometry;
silicon carbide

silicon carbide

silicon
7440-21-3

silicon

Conditions
ConditionsYield
With aluminum oxide In neat (no solvent) byproducts: CO, Al-Si-alloy;
In neat (no solvent)
silicon carbide

silicon carbide

graphite

graphite

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In neat (no solvent) decompn. at about 2500K;;
In neat (no solvent) decompn. in an electric furnace at various temp.;;
In neat (no solvent)
In neat (no solvent)
silicon carbide

silicon carbide

A

pyrographite
7440-44-0

pyrographite

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In neat (no solvent) decompn. at 1 atm. above 2100°C;;
In neat (no solvent) decompn. at 1500-1600°C in high-vac.;;
In neat (no solvent) Kinetics; in a hermetic furnace with a graphite heater in an atmosphere of He; SiC is placed in graphite crucibles with lids and kept at 2770 K for 900, 1800, 2700 and 3600 s; cooled samples are weighed and investigated by chem. anal. and IR-spectrometry;
In neat (no solvent) decompn. at 1500-1600°C in high-vac.;;
In neat (no solvent) decompn. at 1 atm. above 2100°C;;
silicon carbide

silicon carbide

A

silicon monoxide

silicon monoxide

B

silicon
7440-21-3

silicon

Conditions
ConditionsYield
In neat (no solvent) reaction at 2000 °C;;
In neat (no solvent) at 2000°C;;
In neat (no solvent) reaction at 2000 °C;;
In neat (no solvent) reaction at 2000 °C;;
In neat (no solvent)
lithium
7439-93-2

lithium

aluminium
7429-90-5

aluminium

silicon
7440-21-3

silicon

lithium aluminium silicide

lithium aluminium silicide

Conditions
ConditionsYield
In melt in a tantalum tube weld-seald under Ar and protected from air by a silica jacket sealed under vac.; mixt. Li, Al, Si (15:3:6 mol) heated at 1223K, 10 h in vertical furnace and shaken several times;; cooled at rate of 6 K h**-1; elem. anal.;100%
lithium
7439-93-2

lithium

barium
7440-39-3

barium

silicon
7440-21-3

silicon

4Ba(2+)*2Li(1+)*Si6(10-)=Ba4Li2Si6

4Ba(2+)*2Li(1+)*Si6(10-)=Ba4Li2Si6

Conditions
ConditionsYield
In neat (no solvent) Ar atm.; molar ratio Ba:Li:Si 4:2.1:6, 1000°C; cooling (400°C), annealing;100%
strontium(II) hydride

strontium(II) hydride

silicon
7440-21-3

silicon

Sr5Si3H(x)

Sr5Si3H(x)

Conditions
ConditionsYield
In neat (no solvent, solid phase) placing of SrH2 and Si in welded Ta containers, heating within evacuated, well-flamed, sealed silica jacket at 1150°C for 6 h, cooling to650°C with rate of 10-12°C/h;100%
lanthanum
7439-91-0

lanthanum

lanthanum(III) bromide
13536-79-3

lanthanum(III) bromide

silicon
7440-21-3

silicon

La3Br3Si

La3Br3Si

Conditions
ConditionsYield
In neat (no solvent) under Ar, stoich. amt. of starting materials were heated at 1150 °C for 6 days, Ta-tube in an evacuated silica ampoule;100%
lanthanum
7439-91-0

lanthanum

lanthanum(III) iodide
13813-22-4

lanthanum(III) iodide

silicon
7440-21-3

silicon

La3I3Si

La3I3Si

Conditions
ConditionsYield
In neat (no solvent) under Ar, stoich. amt. of starting materials were heated at 1150 °C for 2 days, Ta-tube in an evacuated silica ampoule;100%
lead(II) bromide

lead(II) bromide

methylammonium bromide
6876-37-5

methylammonium bromide

silicon
7440-21-3

silicon

Reaxys ID: 28470675

Reaxys ID: 28470675

Conditions
ConditionsYield
In dichloromethane; N,N-dimethyl-formamide100%
yttrium(III) oxysulfide

yttrium(III) oxysulfide

terbium dioxosulfide

terbium dioxosulfide

sulfur
7704-34-9

sulfur

silicon
7440-21-3

silicon

(Y0.98Tb0.02)4S3(Si2O7)

(Y0.98Tb0.02)4S3(Si2O7)

Conditions
ConditionsYield
With cesium chloride at 1100℃; for 12h; Milling; Sealed tube;100%
yttrium(III) oxysulfide

yttrium(III) oxysulfide

terbium dioxosulfide

terbium dioxosulfide

sulfur
7704-34-9

sulfur

silicon
7440-21-3

silicon

(Y0.96Tb0.04)4S3(Si2O7)

(Y0.96Tb0.04)4S3(Si2O7)

Conditions
ConditionsYield
With cesium chloride at 1100℃; for 12h; Milling; Sealed tube;100%
yttrium(III) oxysulfide

yttrium(III) oxysulfide

europium oxysulfide

europium oxysulfide

sulfur
7704-34-9

sulfur

silicon
7440-21-3

silicon

(Y0.99Eu0.01)4S3(Si2O7)

(Y0.99Eu0.01)4S3(Si2O7)

Conditions
ConditionsYield
With cesium chloride at 1100℃; for 12h; Milling; Sealed tube;100%
yttrium(III) oxysulfide

yttrium(III) oxysulfide

europium oxysulfide

europium oxysulfide

sulfur
7704-34-9

sulfur

silicon
7440-21-3

silicon

(Y0.96Eu0.04)4S3(Si2O7)

(Y0.96Eu0.04)4S3(Si2O7)

Conditions
ConditionsYield
With cesium chloride at 1100℃; for 12h; Milling; Sealed tube;100%
yttrium(III) oxysulfide

yttrium(III) oxysulfide

europium oxysulfide

europium oxysulfide

sulfur
7704-34-9

sulfur

silicon
7440-21-3

silicon

(Y0.90Eu0.10)4S3(Si2O7)

(Y0.90Eu0.10)4S3(Si2O7)

Conditions
ConditionsYield
With cesium chloride at 1100℃; for 12h; Milling; Sealed tube;100%
yttrium(III) oxysulfide

yttrium(III) oxysulfide

sulfur
7704-34-9

sulfur

silicon
7440-21-3

silicon

Y4S3(Si2O7)

Y4S3(Si2O7)

Conditions
ConditionsYield
With cesium chloride at 1100℃; for 12h; Milling; Sealed tube;100%
yttrium(III) oxide

yttrium(III) oxide

selenium
7782-49-2

selenium

silicon
7440-21-3

silicon

Y2SiO4Se

Y2SiO4Se

Conditions
ConditionsYield
With cesium chloride In acetone at 1100℃; under 0.01 Torr; for 12h; Sealed tube;100%
methane
34557-54-5

methane

silicon
7440-21-3

silicon

silicon carbide

silicon carbide

Conditions
ConditionsYield
In gaseous matrix byproducts: graphite; generation of SiO by Heating Si + SiO2 in Ar-stream, mixing with CH4 in H2-stream at 1500-1560°C, pptn. of SiC in cooler reactor zone; X-ray diffraction, electron microscopy, EPMA, EELS;99%
hafnium

hafnium

chromium
7440-47-3

chromium

silicon
7440-21-3

silicon

Hf2Cr4Si5

Hf2Cr4Si5

Conditions
ConditionsYield
In melt Hf, Cr, and Si were pressed into pellets and arc-melted under Ar; X-ray powder diffraction;99%
titanium
7440-32-6

titanium

chromium
7440-47-3

chromium

silicon
7440-21-3

silicon

Ti2Cr4Si5

Ti2Cr4Si5

Conditions
ConditionsYield
In melt Ti, Cr, and Si were pressed into pellets and arc-melted under Ar; X-ray powder diffraction;99%
zirconium
7440-67-7

zirconium

chromium
7440-47-3

chromium

silicon
7440-21-3

silicon

Zr2Cr4Si5

Zr2Cr4Si5

Conditions
ConditionsYield
In melt Zr, Cr, and Si were pressed into pellets and arc-melted under Ar; X-ray powder diffraction;99%
chlorine
7782-50-5

chlorine

silicon
7440-21-3

silicon

tetrachlorosilane
10026-04-7, 53609-55-5

tetrachlorosilane

Conditions
ConditionsYield
In neat (no solvent) heating of amorphous Si in a Cl2 stream at moderate red heat;;98%
In neat (no solvent) reaction of Si in Cl2 atmosphere with inflammation on heating;;
moderate heating;;
cerium
7440-45-1

cerium

magnesium
7439-95-4

magnesium

silicon
7440-21-3

silicon

Ce6Mg23Si

Ce6Mg23Si

Conditions
ConditionsYield
at 700 - 1100℃; for 336h; Sealed tube; Inert atmosphere;98%
silicon
7440-21-3

silicon

dimethylsilicon dichloride
75-78-5

dimethylsilicon dichloride

Conditions
ConditionsYield
With methylene chloride; copper In neat (no solvent) vibrating of the Si-Cu powder;;97%
With methylene chloride; copper In neat (no solvent) CH3Cl and Si-Cu/Cu-oxide at 300-375°C;;82.4%
With methylene chloride; copper In neat (no solvent) CH3Cl and Si purified by treatment with strong acids;;
With methylene chloride In neat (no solvent)
With CH3Cl In neat (no solvent)
nitrogen
7727-37-9

nitrogen

silicon
7440-21-3

silicon

silicon nitride

silicon nitride

Conditions
ConditionsYield
In neat (no solvent) at 1250°C for 20 min; XRD;96%
In neat (no solvent) at 1150°C for 100 min; XRD;95%
In gaseous matrix (H2-He-N2 4%-25%-71%), 1400°C, 15 h;59.9%
ethanol
64-17-5

ethanol

silicon
7440-21-3

silicon

A

tetraethoxy orthosilicate
78-10-4

tetraethoxy orthosilicate

B

Triethoxysilane
998-30-1

Triethoxysilane

Conditions
ConditionsYield
With sebaconitrile; copper(I) oxide In NALKYLENE 500 at 200℃; for 14h; Product distribution / selectivity;A 3.32%
B 95.7%
With octanedinitrile; copper(I) oxide In NALKYLENE 500 at 200℃; for 14 - 21h; Product distribution / selectivity;A 3.45%
B 94.18%
With hexanedinitrile; copper(I) oxide In NALKYLENE 500 at 200℃; for 14h; Product distribution / selectivity;A 5.26%
B 93.38%
phosphorous

phosphorous

silicon
7440-21-3

silicon

silicon monophosphide

silicon monophosphide

Conditions
ConditionsYield
In neat (no solvent) heating Si (in tube of ceramic material) to 1180°C and red P to 400°C;;95%
In neat (no solvent) heating Si (in tube of ceramic material) to 1180°C and red P to 400°C;;95%
vanadia

vanadia

silicon
7440-21-3

silicon

vanadium silicide

vanadium silicide

Conditions
ConditionsYield
In neat (no solvent) byproducts: SiO; powder mixt. cold pressed, than heat-treated in a H2 flow (4KPa) at temp. increasing slowly from 1200 to 1400°C for 2h, kept at 1450-1500°C for 2h;95%
europium dihydride

europium dihydride

silicon
7440-21-3

silicon

Eu5Si3H(x)

Eu5Si3H(x)

Conditions
ConditionsYield
In neat (no solvent, solid phase) placing of EuH2 and Si in welded Ta containers, heating within evacuated, well-flamed, sealed silica jacket at 1150°C for 6 h, cooling to650°C with rate of 10-12°C/h;95%
calcium hydride
7789-78-8

calcium hydride

silicon
7440-21-3

silicon

Ca5Si3H(x)

Ca5Si3H(x)

Conditions
ConditionsYield
In neat (no solvent, solid phase) placing of CaH2 and Si in welded Ta containers, heating within evacuated, well-flamed, sealed silica jacket at 1150°C for 6 h, cooling to650°C with rate of 10-12°C/h;95%
barium hydride

barium hydride

silicon
7440-21-3

silicon

Ba5Si3H(x)

Ba5Si3H(x)

Conditions
ConditionsYield
In neat (no solvent, solid phase) placing of BaH2 and Si in welded Ta containers, heating within evacuated, well-flamed, sealed silica jacket at 1150°C for 6 h, cooling to650°C with rate of 10-12°C/h;95%
strontium

strontium

silicon
7440-21-3

silicon

Sr5Si3

Sr5Si3

Conditions
ConditionsYield
In neat (no solvent, solid phase) placing of Sr and Si in welded Ta containers, heating under vac. at 1300°C for 6 h, cooling to 600°C with rate of 8°C/h;95%

7440-21-3Relevant articles and documents

Hydrostatic pressure dependence of the photoluminescence of Si nanocrystals in SiO2

Cheong, Hyeonsik M.,Paul,Withrow,Zhu,Budai,White,Hembree Jr.

, p. 87 - 89 (1996)

We have measured the hydrostatic pressure dependence of the photoluminescence (PL) of Si nanocrystals in SiO2 layers at room temperature and at pressures up to 50 kbar. The samples were fabricated by ion implantation and subsequent annealing. For the two

Mechanism of photoluminescence of Si nanocrystals fabricated in a SiO2 matrix

Zhuravlev,Gilinsky,Kobitsky

, p. 2962 - 2964 (1998)

The luminescence properties of silicon nanocrystals fabricated by Si ion implantation into a SiO2 matrix and subsequent thermal annealing have been studied. To identify the mechanism of photoluminescence of Si nanocrystals, the dependencies of the steady-state photoluminescence on temperature and excitation power density, and the time-resolved photoluminescence have been investigated. The experimental results point to the mechanism of recombination via the levels of centers which are presumably localized at the silicon nanocrystal-silicon dioxide boundary.

Thermally deposited amorphous silicon

Mieno,Sukegawa,Iizuka,Miyata,Nomura,Tsukune,Furumura

, p. 2166 - 2171 (1994)

We investigated a thermally deposited amorphous silicon (TAS) film before and after annealing. We used monosilane (SiH4) or disilane (Si2H6) as the Si source gas at a deposition pressure of 0.1 to 0.5 Torr. The activation energy of SiH4 deposition was 1.7 eV (560 to 600 °C) and that of Si2H6 was 0.6 eV (510 to 570 °C). From TEM observation, the TAS film from 450 °C Si2H6 deposition was completely amorphous without crystals and had a smooth surface. Film deposited at 560 °C had a few crystals at the Si/SiO2 interface and had a few bumps on the Si surface. After annealing, the mean grain size of 450 °C-Si2H6 film was about 2 μm and that of 560 °C-SiH4 film was about 0.3 μm. We also evaluated the crystallinity by XRD and Raman spectroscopy. Films deposited at lower temperatures after annealing showed strong 〈111〉-orientations and high crystal qualities.

The metallic Zintl phase Ba3Si4 - Synthesis, crystal structure, chemical bonding, and physical properties

Aydemir, Umut,Ormeci, Alim,Borrmann, Horst,Boehme, Bodo,Zuercher, Fabio,Uslu, Burcu,Goebel, Thorsten,Schnelle, Walter,Simon, Paul,Carrillo-Cabrera, Wilder,Haarmann, Frank,Baitinger, Michael,Nesper, Reinhard,Von Schnering, Hans Georg,Grin, Yuri

, p. 1651 - 1661 (2008)

The Zintl phase Ba3Si4 has been synthesized from the elements at 1273 K as a single phase. No homogeneity range has been found. The compound decomposes peritectically at 1307(5) K to BaSi2 and melt. The butterfly-shaped Si46- Zintl anion in the crystal structure of Ba3Si4 (Pearson symbol tP28, space group P42/mnm, a = 8.5233(3) A, c = 11.8322(6) A) shows only slightly different Si-Si bond lengths of d(Si-Si) = 2.4183(6) A (1x) and 2.4254(3) A (4x). The compound is diamagnetic with χ ≈ -50 × 10-6 cm3 mol-1. DC resistivity measurements show a high electrical resistivity (ρ(300 K) ≈ 1.2 × 10 -3 Ω m) with positive temperature gradient dρ/dT. The temperature dependence of the isotropic signal shift and the spin-lattice relaxation times in 29Si NMR spectroscopy confirms the metallic behavior. The experimental results are in accordance with the calculated electronic band structure, which indicates a metal with a low density of states at the Fermi level. The electron localization function (ELF) is used for analysis of chemical bonding. The reaction of solid Ba3Si4 with gaseous HCl leads to the oxidation of the Si46- Zintl anion and yields nanoporous silicon.

Nanometer-scale Si selective growth on Ga-adsorbed voids in ultrathin SiO2 films

Nitta, Yoshiki,Shibata, Motoshi,Fujita, Ken,Ichikawa, Masakazu

, p. L565-L569 (1999)

We examined nanometer-scale Ga selective doping by Si growth on Ga-adsorbed voids in ultrathin silicon-dioxide on Si(111) surfaces. The doping processes were observed by scanning tunneling microscopy (STM). Voids in ultrathin oxide films were plugged with a (√3 × √3)-Ga structure, and the selective growth was performed by introducing disilane gas (Si2H6). Si crystals were selectively grown only in the voids at 460-550°C. Two-dimensional nucleation was found to start from the edge of the voids. Incorporated Ga atoms mostly segregated during the selective growth and were reconstructed to the (√3 × √3) structure by annealing at 600°C. These results show that Ga doped dots of nanometer-scale can be formed by selective epitaxial growth using an ultrathin silicon-dioxide mask.

Efficient defect passivation by hot-wire hydrogenation

Plieninger,Wanka,Kuehnle,Werner

, p. 2169 - 2171 (1997)

Atomic hydrogen, produced at a hot wire, passivates bulk defects in polycrystalline silicon without damaging surface regions. Solar cells from such polycrystalline silicon respond much more favorably to hot-wire hydrogenation than to low-energy ion implantation or a direct-current plasma treatment. Hot-wire passivation yields a hydrogen concentration close to the surface of 8 × 1019 cm-3 and improves the minority carrier diffusion length of solar cells by up to 100%. Implantation as well as conventional plasma treatment result in lower hydrogen concentration and, consequently, in much smaller improvements of diffusion lengths.

Roles of SiH4 and SiF4 in growth and structural changes of poly-Si films

Haddad-Adel,Inokuma,Kurata,Hasegawa

, p. 1429 - 1436 (2007)

The structural properties of polycrystalline silicon films, prepared by plasma enhanced chemical vapor deposition system, with different flow rates of SiH4/SiF4 mixtures at 300 °C were investigated. This study indicates that the low

Synthesis of Crystalline Silicon Tubular Nanostructures with ZnS Nanowires as Removable Templates

Hu, Junqing,Bando, Yoshio,Liu, Zongwen,Zhan, Jinhua,Goldberg, Dmitri,Sekiguchi, Takashi

, p. 63 - 66 (2004)

Silicon epitaxy on ZnS nanowires results in the formation of ZnS/Si core/shell nanowires; chemical removal of the zinc blende nanowire templates produces monocrystalline silicon tubular nanostructures with outer diameters of about 60-180 nm, wall thicknes

CATHODIC DEPOSITION OF AMORPHOUS SILICON FROM TETRAETHYLORTHOSILICATE IN ORGANIC SOLVENTS.

Takeda,Kanno,Yamamoto,Mohan,Chia-Hao Lee,Kroger

, p. 1221 - 1224 (1981)

A blue thin film of amorphous silicon has been deposited on a nickel cathode by the electrolysis of a solution of tetraethylorthosilicate in acetic acid. The maximum thickness of the film obtained was about 0. 5 mu m. The deposit was confirmed to be amorphous silicon by IR reflection spectra, RHEED, and nondispersive x-ray analysis in the scanning electron microscope. This work is pertinent to solar cells.

Theoretical/experimental study of silicon epitaxy in horizontal single-wafer chemical vapor deposition reactors

Kommu, Srikanth,Wilson, Gregory M.,Khomami, Bamin

, p. 1538 - 1550 (2000)

The main goal of this study is to examine the possibility of using detailed three-dimensional simulations of transport of momentum, energy, and mass in horizontal single-wafer epitaxial silicon reactors in conjunction with relatively simple kinetic models to describe the reactor's performance over the entire range of operating conditions. As the SiHCl3-H2 system is a widely used precursor for epitaxial silicon deposition in industrial applications, we have chosen to focus our model development on this system. In the development of the model we have considered the dependence of the gas properties on the gas composition as well as on the temperature. In addition, mass transport due to thermal diffusion has been considered. The accuracy of the simulation model has been examined by comparing the predicted silicon deposition rates and profiles in two commercial chemical vapor deposition (CVD) reactors with the experimentally measured values. A comparison of simulation and experimental results has indicated that a detailed transport model in conjunction with a Langmuir-Hinshelwood type kinetic model for silicon deposition accurately describes the epitaxial silicon deposition rate and deposition profile. In turn, this lumped reaction kinetic model has been used for optimization of commercially available horizontal CVD reactors for epitaxial deposition of silicon.

Optical properties of n-type porous silicon obtained by photoelectrochemical etching

Chen,Chen

, p. 681 - 685 (1999)

The optical studies of n-type porous silicon prepared by the photo-assisted chemical etching are reported here. The optical properties of samples obtained under different conditions have been investigated by photoluminescence and Fourier transform infrared absorption measurements, and they are compared with that of p-type porous silicon. Our results clearly demonstrate that the blue emission in porous silicon originates from surface compounds. From the infrared absorption measurement, we point out that the surface compounds are Si-OH complexes. This conclusion is further supported by a recent calculation which shows that Si-OH complexes can emit the photon energy in the range observed here. We show that the optical properties of the n-type porous silicon are more stable than that of the p-type porous silicon. The result provides the evidence to support the fact that the n-type porous silicon is a better candidate for the application in optoelectronics.

Wide fluctuations in fluorescence lifetimes of individual rovibronic levels in SiH2 (1B1)

Thoman, J. W.,Steinfeld, J. I.,McKay, R. I.,Knight, A. E. W.

, p. 5909 - 5917 (1987)

We have measured fiuorescence lifetimes of individual rovibronic levels in SiH2 (1B1,020).The lifetimes vary widely from one level to the next, ranging from 10 ns to 1 μs.Similar behavior is seen in the (000), (010), and (03

Fabrication of poly-Si films by continuous local thermal chemical vapor deposition on flexible quartz glass substrate

Nakamura,Kuraseko,Hanazawa,Koaizawa,Uraoka,Fuyuki,Mimura

, (2008)

The continuous deposition of polycrystalline silicon film on quartz fiber by local thermal chemical deposition was investigated. High-speed deposition owing to high temperature and locality was examined using fixed and moving substrates. We confirmed the high-speed deposition of polycrystalline silicon and achieved a maximum speed of over 1 μms. Furthermore, we succeeded in a continuous deposition of polycrystalline thin silicon with a thickness of 50-100 nm on a quartz fiber with low roughness and low impurity content. Thin film transistor with a mobility more than 3.7 cm2 V s was achieved by using this film.

Absorption spectroscopy of SiH2 near 640 nm

Escribano, Rafael,Campargue, Alain

, p. 6249 - 6257 (1998)

The A 1B1-X 1A1 absorption spectrum of SiH2 has been observed using intracavity laser absorption spectroscopy with an equivalent path length of up to 13.0 km and the A 1B1(0, 0, 0)-X 1A1(0, 0, 0) band near 640 nm recorded for the first time. The silylene radical was generated in a continuous discharge in a flowing mixture of silane in argon, giving a concentration of the order of 1010 SiH2/cm3. The spectrum spans the region between 15350 and 16100 cm-1. Rotational transitions have been assigned to levels up to J = 16 and Ka = 9, with ΔKa up to 5, ΔKc up to 4. Perturbations have been detected in the spectrum, due to Renner-Teller and spin-orbit interactions between both electronic states and the 3B1 state, predicted to be between them. However, the strength of the irregular perturbations affecting the rotational states of A 1B1(0,0,0) state is found to be much weaker than that affecting the other (0, v′2, 0) levels previously studied. The analysis of the spectrum has allowed the determination of the rotational constants of the 1B1 (0,0,0) level, and a new estimation of those of the vibrational and electronic ground state. The geometry of the excited electronic level has also been determined for the first time from accurate experimental data. A change in the structure of this molecule takes place with this transition, the equilibrium angle opening from 92° to 122.4°, while the bond distance is reduced from 1.51 to 1.485 A.

Clathrates of group 14 with alkali metals: An exploration

Bobev, Svilen,Sevov, Slavi C.

, p. 92 - 105 (2000)

The quantitative synthesis of four silicon and germanium compounds with the clathrate-II structure, Cs8Na16Si136 (1), Cs8Na16Ge136 (2), Rb8Na16Si136 (3), and Rb8Na16Ge36 (4), and their characterizations are reported. The corresponding Si-Si and Ge-Ge distances are determined with high accuracy from extensive single-crystal X-ray diffraction work. The compounds (cubic, space group Fd3m, a=14.7560(4), 15.4805(6), 14.7400(4), and 15.4858(6) A for 1, 2, 3, and 4, respectively) are stoichiometric, metallic, and remarkably stable. No evidence was found for vacancies in the silicon and germanium networks or partial occupancies of the alkali metal sites. The stoichiometry of these completely filled clathrates is consistent with the measured temperature-independent Pauli paramagnetism (χ = 7.2 x 10-4, 6.5 x 10-4, 6.9 x 10-5, and 1.4 x 10-4 emu/mol for 1, 2, 3, and 4, respectively) and metallic resistivity (ρ293 ? 10-5 Ω-cm). (C) 2000 Academic Press.

Separation of silicon isotopes by silicon tetrafluoride-silane technology

Korolev,Mashirov,Perepech,Polyakov,Shil'nikov,Godisov,Kaliteevskii,Ber,Kovarskii

, p. 539 - 541 (2002)

Silane enriched in silicon isotopes was obtained in high yield by reacting SiF4 with a solution of NaAlH4 in diethylene glycol dimethyl ether in a purpose-designed apparatus. Chemical analyses are presented for isotopically enriched silicon obtained by the thermal decomposition of silane.

Micro-Raman spectroscopy of Si nanowires: Influence of diameter and temperature

Torres,Martin-Martin,Martinez,Prieto,Hortelano,Jimnez,Rodriguez,Sangrador,Rodriguez

, (2010)

Raman spectroscopy provides nondestructive information about nanoscaled semiconductors by modeling the phonon confinement effect. However, the Raman spectrum is also sensitive to the temperature, which can mix with the size effects borrowing the interpret

Nanocrystal-mediated crystallization of silicon and germanium nanowires in organic solvents: The role of catalysis and solid-phase seeding

Tuan, Hsing-Yu,Lee, Doh C.,Korgel, Brian A.

, p. 5184 - 5187 (2006)

(Figure Presented) The top seed: Various metal nanocrystals are studied as crystallization seeds for silicon and germanium nanowires. The wires are grown by decomposing silane or germane reactants in supercritical organic solvents. Co and Ni nanocrystals

Wong-Leung, J.,Nygren, E.,Williams, J. S.

, p. 416 - 418 (1995)

1.5 μm luminescence of silicon nanowires fabricated by thermal evaporation of SiO

Jia,Kittler,Su,Yang,Sha

, p. R55-R57 (2006)

Silicon nanowires (NWs) fabricated by thermal evaporation of SiO were studied by cathodoluminescence. A band around 1550 nm (0.8 eV) was observed. It appears above 225 K and its intensity increases with increasing temperature. The broad band consists of the defect-related D1 and D2 lines and is supposed to be formed by extended defects within the NWs that are decorated with oxygen. Moreover, luminescence bands are found that are related to Si oxide and/or the interface between Si and Si oxide. In addition, the Si band-to-band line and the G center are observed.

Synthesis of coaxial nanowires of silicon nitride sheathed with silicon and silicon oxide

Wu,Song,Zhao,Huang,Pu,Sun,Du

, p. 683 - 686 (2000)

Coaxial nanowires, with about 45 nm in diameter and about 15 μm in length, have been synthesized by reaction of silicon dioxide nanoparticles with active carbon at 1450 °C in flowing nitrogen atmosphere. Their structures consist of an α-phase silicon nitride core, an amorphous silicon and a silicon dioxide outer shell, similar to those of coaxial nanocables. The formation mechanism of the coaxial nanowires is discussed.

Shock-induced transformation of β-Si3N4 to a high-pressure cubic-spinel phase

Sekine,He, Hongliang,Kobayashi,Zhang, Ming,Xu, Fangfang

, p. 3706 - 3708 (2000)

β-Si3N4 powders were shock compressed and quenched from 12 to 115 GPa. β-Si3N4 transforms to the spinel-type Si3N4 (c-Si3N4) by a fast reconstructive process at pressures above about 20 GPa. The yield of c-Si3N4 recovered from 50 GPa and about 2400 K reaches about 80% and the grain sizes are about 10-50 nm. It is proposed that the fast transformation to c-Si3N4 occurs by rearrangement of nitrogen stacking layers, which initiates partial breakup of the SiN4 tetrahedra and formation of SiN6 octahedra at high density. Because of the advantages of massive production and the nanometer characteristics of shock-synthesized c-Si3N4, it is possible to investigate the mechanical properties experimentally and to develop new industrial applications.

Silicon molecular layer epitaxy

Nishizawa,Aoki,Suzuki,Kikuchi

, p. 1898 - 1904 (1990)

This paper reports on recent results of silicon molecular layer epitaxy (MLE) using SiH2Cl2 and hydrogen. Growth conditions for monomolecular layers by the monomolecular layer deposition process have been investigated as a function o

PRODUCTION OF SILICON FOR SOLAR CELLS: PRESSURE EFFECTS ON THE SiF4-Na REACTION AND ITS PRODUCTS.

SANJURJO,NANIS

, p. 437 - 451 (1981)

The effects of the SiF//4 pressure on the SiF//4-Na reaction and its products have been studied. Constant volume batch experiments were carried out in which Na, preheated to 250 degree C, was exposed to SiF//4 at different pressures. Because of the exothermic character of the reaction, the temperature at the reaction zone peaks to a maximum that depends on the pressure of SiF//4. At SiF//4 pressure around 1 atm, the temperature maximum reaches the highest values, near the melting point of silicon (1412 degree C). Depending on the SiF//4 pressure, three distinct reaction behaviors and corresponding reaction products can be identified. The pressure range of more interest for practical application of the SiF//4-Na reaction lies between 350 and 760 torr. At these pressures, clear segregation between the Si and NaF phases is observed and the average Si particle size is 0. 2 mm.

Silicene: Wet-Chemical Exfoliation Synthesis and Biodegradable Tumor Nanomedicine

Lin, Han,Qiu, Wujie,Liu, Jianjun,Yu, Luodan,Gao, Shanshan,Yao, Heliang,Chen, Yu,Shi, Jianlin

, (2019)

Silicon-based biomaterials play an indispensable role in biomedical engineering; however, due to the lack of intrinsic functionalities of silicon, the applications of silicon-based nanomaterials are largely limited to only serving as carriers for drug delivery systems. Meanwhile, the intrinsically poor biodegradation nature for silicon-based biomaterials as typical inorganic materials also impedes their further in vivo biomedical use and clinical translation. Herein, by the rational design and wet chemical exfoliation synthesis of the 2D silicene nanosheets, traditional 0D nanoparticulate nanosystems are transformed into 2D material systems, silicene nanosheets (SNSs), which feature an intriguing physiochemical nature for photo-triggered therapeutics and diagnostic imaging and greatly favorable biological effects of biocompatibility and biodegradation. In combination with DFT-based molecular dynamics (MD) calculations, the underlying mechanism of silicene interactions with bio-milieu and its degradation behavior are probed under specific simulated physiological conditions. This work introduces a new form of silicon-based biomaterials with 2D structure featuring biodegradability, biocompatibility, and multifunctionality for theranostic nanomedicine, which is expected to promise high clinical potentials.

A silicon–carbonyl complex stable at room temperature

Ganesamoorthy, Chelladurai,Schoening, Juliane,W?lper, Christoph,Song, Lijuan,Schreiner, Peter R.,Schulz, Stephan

, p. 608 - 614 (2020/05/05)

Main-group-element compounds with energetically high-lying donor and low-lying acceptor orbitals are able to mimic chemical bonding motifs and reactivity patterns known in transition metal chemistry, including small-molecule activation and catalytic reactions. Monovalent group 13 compounds and divalent group 14 compounds, particularly silylenes, have been shown to be excellent candidates for this purpose. However, one of the most common reactions of transition metal complexes, the direct reaction with carbon monoxide and formation of room-temperature isolable carbonyl complexes, is virtually unknown in main-group-element chemistry. Here, we show the synthesis, single-crystal X-ray structure, and density functional theory computations of a room-temperature-stable silylene carbonyl complex [L(Br)Ga]2Si:–CO (L = HC[C(Me)N(2,6-iPr2-C6H3)]2), which was obtained by direct carbonylation of the electron-rich silylene intermediate [L(Br)Ga]2Si:. Furthermore, [L(Br)Ga]2Si:–CO reacts with H2 and PBr3 with bond activation, whereas the reaction with cyclohexyl isocyanide proceeds with CO substitution. [Figure not available: see fulltext.]

Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts

Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias

supporting information, (2019/04/17)

Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)CNtBu, Ph2CCH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).

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