420-04-2 Usage
Uses
Used in Pesticide Industry:
Cyanamide is used as an important intermediate for the production of various pesticides, including carbendazim, benzene benomyl, methyl mepanipyrim, mepanipyrim, Pirimicarb, pyrimidinoxy phosphorus, herbicides such as Chlorsulfuron, Metsulfuron methyl, Metsulfuron methyl ethyl, long ether tribenuron methyl, bensulfuron methyl, and pyrazole ethyl, hexazinone, etc.
Used in Pharmaceutical Industry:
Cyanamide is used as a raw material for the production of hydrochloric acid and as a production intermediate for 3-amino-5-hydroxyl-1,2,4-triazol in the dye industry. It is also used in organic synthesis and plastic raw materials for the production of cyanuric amide, dicyandiamide, and cyanide methyl carbamate.
Used in Agriculture:
Cyanamide liquid is used as an industrial raw material, pharmaceutical intermediate, agricultural pesticide, fertilizer, plant growth regulator, and food additive.
Used in Europe:
In Europe, cyanamide is used as a fertilizer, weed killer, and defoliant. It is also used to produce cationic starch, calcium cyanide, dicyandiamide, and melamine.
New Uses:
Cyanamide has new applications as intermediates for pesticides, detergents, medicines such as antihistamines, hypertension, sedatives, and contraceptives, photography industry, additive for fuels and lubricants, paper preservative, and cement additive.
Used as a Rest-Breaking Agent:
Cyanamide is used as a common rest-breaking agent called Dormex, applied in spring to stimulate uniform opening of buds.
Used in Treating Alcoholism:
Cyanamide has been tested as an effective and well-tolerated pharmacological adjunct to treat alcohol-dependent patients. It is a potent aldehyde dehydrogenase inhibitor and alters cholinergic function in the frontal cortex and hippocampus of rats exposed to ethanol.
Used in Chemical Synthesis:
Cyanamide is commonly used in liquid solution and is expected to be soluble in water, ether, benzene, acetone, phenols, amines, ketones, and alcohols. It is used mainly in agriculture as a rest-breaking agent and in pharmaceutical industries in the production of antihistamines, antihelminthics, and many other drugs.
Used in Fumigants, Metal Cleaners, and Synthetic Rubber Production:
Cyanamide is also used in the production of fumigants, metal cleaners, and synthetic rubber, as well as in chemical synthesis.
Physicochemical property
Cyanamide is also called hydrogen cyanamide，urine anhydride, its scientific name is amino nitrile. It is white orthogonal series crystals, in a diamond shaped, colorless, easy moisture. Melting point is 42℃, boiling point is 83℃ (50.66kPa), vapor pressure is (20℃) is 500MPa. Cyanamide is high solubility in water and weak acid, and completely miscible in water of 43℃. It is soluble in benzene and phenol, alcohols, amines, ethers, ketones, slightly soluble in benzene, halogenated hydrocarbons, but insoluble in epoxy ethane, cyclohexane. Solubility (20℃ ): water 4.59kg/L, methyl ethyl ketone 505g/kg, acetic acid ethyl ester 424g/kg, octanol 288g/kg, chloroform 2.4 g/kg. It can volatilize with water vapor, so it can dissolve in a series of solvents. In polar organic solvent, solubility is large, and in non-polar solvents is smaller. Crystal cyanamide is not stable, large polarity. Due to the cyanamide molecular structure containing the cyano and amino, both of which are active groups, it has the functional groups of the multiple reaction performance, prone to addition, substitution, condensation reaction. It is stable to light. It decomposites to dicyandiamide and polymers in alkali, and decomposites to urea in acid. It decompose when heated to 180℃. Product has four kinds of crystal of 25%, 40%, 50% and 90%. 25% of cyanamide solution is mainly used for creatine production, 50% and 90% of cyanamide solutions are mainly used for producing methylene urea pharmaceutical intermediates.
Figure 1 Three-dimensional structure of cyanamide
Main application
1. Important pharmaceutical raw material
Cyanamide is mainly used for the production of hydrochloric acid cytarabine, dye intermediate 3-amino-5-hydroxy-1,2,4-nitrogen azole, cyanide urea amine, melamine methyl carbamate, cyanide urine amide, thiourea, carbendazim. It is also raw material for preparation of organic guanidine, then the product pharmaceutical barbituric acid, sulfa drugs and guanidine salt, etc. It can also be used for production anticancer drugs of fluorouracil in medicine. Cyanamide calcium salt can be used for clinical treatment of alcoholism and anthelmintic action.
2. Raw materials for chemical pesticides
2.1 Cyanamide can be used as chemical raw materials of no residue, low toxicity, broad-spectrum pesticide, and can also be used for production of antibacterial agent such as carbendazim, benzene benomyl, methyl mepanipyrim and mepanipyrim, Pirimicarb, pyrimidinoxy phosphorus, herbicide Chlorsulfuron, Metsulfuron methyl, Metsulfuron methyl ethyl, long ether tribenuron methyl and bensulfuron methyl and pyrazole ethyl, hexazinone, etc. It has the significance of technological innovation for pesticide production, solves the environmental pollution while the general pesticide production enterprises can be difficult to solve the problem using calcium cyanamide in the production of pesticide. So using cyanamide can save equipment investment, reduce production costs.
2.2 In recent years, cyanamide is used as off leaf agents, herbicides and pesticides in abroad, but also can be used as pesticide, and cyanamide has a certain of nitrogen application effect. Cyanamide solution was used as a defoliant, non-toxic pesticides for fruit trees in abroad.
2.3 The cyanamide in agriculture can be used as plant growth regulators, with both pesticidal and bactericidal effects. Directly sprayed on crops, can effectively inhibit the activity of catalase in plants, accelerate plant oxidative pentose phosphate (PPP) circulation, thus speeding up the generation of basic substances in plants, play a role in the regulation of growth. The field efficacy trials showed that It can regulate the growth and increase production of cherries and grapes. Before 15 to 20 days in grape germination, it sprayed evenly on the branches, uniform of a drug on bud eye, can advance germination of 7 to 10 days. For early flowering, full flowering stage, coloring period and mature period, using it can aslo advance early. At the same time it is good dormancy terminating agent in the production of kiwi, cherries, grapes. it sprayed evenly on bud eye in the dormant period, it can break the dormancy period, can be early germination, early flowering, early mature and early on the market. It can significantly improve the yield, change fruit fleshy and improve the quality of varieties.
Excellent flame retardant materials
The cyanamide is mainly used for production of flame retardant agent such as o-methyl isourea, creatine, guanidine phosphate. At the same time, as a kind of flame retardant material with excellent performance, cyanamide polyols and polyether solution are used for production of polyurethane, can significantly improve the flame retardancy of polyurethane material, which is a new type of fine chemical new materials.
Fixing material
The materials from the two polymer fixing agent melamine dicyandiamide can be used in the production of fixing agent Y, fixing agent G, fixing agent M and fixing agent B. Reaction product of cyanamide, poly formaldehyde and acid copper is fixing agent B, which is gray powder, can be used for direct dyes and staining after treatment. 30.9 copies of diethylenetriamine and 24.8 dicyandiamide react under 100℃, then reaction again in 155 ℃, after 5h cooling, crushing to obtain colorless powder. It is a kind of formaldehyde-free fixing agent, low cost, having a development promising as green products.
Toxicity
1. It has the skin irritation and corrosive, can lead to severe dermatitis, the person suction can cause mucosal irritation, transient flushing, headache, dizziness, shortness of breath, tachycardia and hypertension and other symptoms.
2. Mutagenicity test: mild irritation to rabbit skin and eye severe stimulation, the drug of guinea pig skin allergic reaction test is attenuated sensitive drugs.
3.The effect maximum dose is 0.2mg/kg/d in rats with 90d sub chronic feeding experiment. Cyanamide drug and 50% aqueous solution are medium toxicity. Please use it to Caution!
Chemical property
Pure cyanamide is a transparent liquid, m.p.-115℃, b.p.-8.5℃, soluble in alcohols, phenols, amines, ethers, easily soluble in benzene, alkyl halides, 77.5% of it is soluble in water of 15℃. The high concentration of cyanamide is not stable, easy polymerization, often adding stabilizer. General merchandise for 50% of cyanamide solution, n20D 1.4050, the relative density is 1.082.
Methods of production
1.It is gotten by the reaction of lime nitrogen with sulphuric acid。
The preparation method is based on the lime nitrogen as raw material, reaction with sulfuric acid is made. In the reactor, the water is putted, with ice water cooling, lime nitrogen input, the temperature was kept between 0 to 15℃, dropping 5% of sulfuric acid solution, adjusting the pH = 6 and holding 20 min. Then filtration, washing, and then return to a reaction kettle, added lime nitrogen, repeat the above operation 2 times, the obtained filtrate is through membrane thickening, keeping a certain temperature, concentrated content reached 50%~55%, Cyanamide solution of 50% is obtained.
Reaction equation: CaCN2+H2O+H2SO4-> NH2CN+CaSO4
2. Urea process。
Production Methods
The basic process for the manufacture of cyanamide comprises
four steps. The first three steps produce calcium
cyanamide: lime is made from high grade limestone;
(2) calcium carbide is manufactured from lime and coal or
coke; calcium cyanamide is produced by passing gaseous
nitrogen through a bed of calcium carbide with 1% calcium
fluorspar, which is heated to 1000–1100°C to start the
reaction—the heat source is then removed and the reaction
continues because of its strong exothermic character; and
cyanamide is manufactured from calcium cyanamide by
continuous carbonation in an aqueous medium.
Reactions
Cyanamide reacts (1) as a base with strong acids forming salts, (2) as an acid forming metallic salts, such as calcium cyanamide CaCN2. Cyanamide is formed (1) by reaction of cyanogen chloride CN·Cl plus ammonia (ammonium chloride also formed), (2) by reaction of thiourea plus lead hydroxide (lead sulfide also formed).
Reactivity Profile
Cyanamide is the amide of cyanic acid. Non-flammable but combustible (flash point: 140°C). Decomposes on warming above 49°C. Emits toxic fumes of CN- and NOx when heated to decomposition or on contact with acids or acid fumes (Hazardous Chemicals Desk Reference, p. 353 (1987)). Contact with moisture, acids or bases may cause a violent reaction at temperatures above about 40°C. Dry solid may polymerize at temperatures above 122°C. Rapid or explosive polymerization may occur during the evaporation of aqueous solutions. Reacts explosively with strong oxidizing agents and strong reducing agents. Attacks various metals (International Chemical Safety Card).
Hazard
Strong irritant to skin and mucous membranes; avoid inhalation or ingestion.
Health Hazard
Cyanamide is an irritant of the
eyes, mucous membranes, and skin; it is an
inhibitor of aldehyde dehydrogenase and can
cause an “antabuse” effect with ethanol
ingestion.
Cyanamide is severely irritating and
caustic to the eyes, skin, and respiratory tract.
Flammability and Explosibility
Notclassified
Trade name
DORMEX?; SKW 83010?
Contact allergens
Cyanamide and its salts are used in various occasions
such as in chemistry, in antirust solutions, or in a drug
(Come?) for treating alcoholism (inhibition of alcohol
deshydrogenase).
Safety Profile
Poison by ingestion,
inhalation, and intraperitoneal routes.
Moderately toxic by skin contact.
Experimental reproductive effects.
Combustible when exposed to heat or
flame. To fight fire, use CO2, dry chemical.
Thermally unstable. Contact with moisture
(water), acids, or alkalies may cause a violent
reaction above 40'. Concentrated aqueous
solutions may undergo explosive
polymerization. Mixture with 1,2
phenylenediamine salts may cause explosive
polymerization. When heated to
decomposition or on contact with acid or
acid fumes, it emits toxic fumes of CNand
NOx. See also CYANIDE and AMIDES.
Potential Exposure
Cyanamide may be melted to give a
dimer, dicyandiamide or cyanoguanidine. At higher tem-
peratures it gives the trimer, melamine; a raw material for
melamine-form aldehyde resins.
Shipping
UN3276 Nitriles, liquid, toxic, n.o.s., Hazard
Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name
Required, Potential Inhalation Hazard (Special Provision 5).
Purification Methods
Purify it by placing ca 15g in a Soxhlet thimble and extracting exhaustively (2-3hours) with two successive portions of Et2O (400mL, saturated with H2O by shaking before use) containing two drops of 1N acetic acid. Two successive portions of Et2O are used so that the NH2CN is not heated for too long. Each extract is dried over Na2SO4 (30g), then combined and evaporated under reduced pressure. The NH2CN may be stored unchanged at 0o in Et2O solution in the presence of a trace of AcOH. Extracts from several runs may be combined and evaporated together. The residue from evaporation of an Et2O solution is a colourless viscous oil which sets to a solid and can be recrystallised from a mixture of 2 parts of *C6H6 and 1 part of Et2O. Concentrating an aqueous solution of NH2CN at high temperatures causes EXPLOSIVE polymerisation. [Kurzer & Lawson Org Synth Coll Vol IV 645 1963, Pinck & Salissbury Inorg Synth III 39 1950, Soloway & Lipschitz J Org Chem 23 613 1958.] Hygroscopic.[Beilstein 3 IV 145.]
Toxicity evaluation
Adsorption–desorption studies in soil have estimated very low
Koc values (0–6.81 ml g-1 ) indicating low adsorption and high
mobility potential of cyanamide in soil; however, soil column
leaching studies indicate that cyanamide is only slightly
mobile. Volatilization is not expected to be an important fate
and transport process based on the Henry’s law constant and
vapor pressure. When released into the air, vapor phase cyanamide
is expected to have a half-life of less than 1 day. Aerobic
biodegradation is expected to occur, with cyanamide serving as
source of nitrogen and carbon. The estimated half-life of
cyanamide from the water phase of the aquatic systems was 2.3
days for the river system and 4.3 days for the pond system,
respectively. Bioconcentration and bioaccumulation potential
is expected to be low, based on the estimated bioconcentration
factor and experimental octanol–water partition coefficient.
Incompatibilities
Cyanamide may polymerize at tempera-
tures above 122℃
, or on evaporation of aqueous solutions.
Reacts with acids, strong oxidants, strong reducing agents
such as hydrides and water, causing explosion and toxic
hazard. Attacks various metals. Decomposes when heated
above 49℃
C, on contact with acids, bases, 1,2-phenylene
diamine salts; and moisture; producing toxic fumes includ-
ing nitrogen oxides and cyanides. Nitriles may polymerize
in the presence of metals and some metal compounds.
They are incompatible with acids; mixing nitriles with
strong oxidizing acids can lead to extremely violent reac-
tions. Nitriles are generally incompatible with other oxi-
dizing agents such as peroxides and epoxides. The combination of bases and nitriles can produce hydrogen
cyanide. Nitriles are hydrolyzed in both aqueous acid and
base to give carboxylic acids (or salts of carboxylic
acids). These reactions generate heat. Peroxides convert
nitriles to amides. Nitriles can react vigorously with
reducing agents. Acetonitrile and propionitrile are soluble
in water, but nitriles higher than propionitrile have low
aqueous solubility. They are also insoluble in aqueous
acids
.
Waste Disposal
Add excess alkaline calcium
hypochlorite with agitation. Flush to sewer after 24 hours.
Cyanamide can also be destroyed in an incinerator
equipped with afterburner and scrubber.
Check Digit Verification of cas no
The CAS Registry Mumber 420-04-2 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,2 and 0 respectively; the second part has 2 digits, 0 and 4 respectively.
Calculate Digit Verification of CAS Registry Number 420-04:
(5*4)+(4*2)+(3*0)+(2*0)+(1*4)=32
32 % 10 = 2
So 420-04-2 is a valid CAS Registry Number.
InChI:InChI=1/CH2N2/c2-1-3/h2H2
420-04-2Relevant articles and documents
Mechanism Involving Hydrogen Sulfite Ions, Chlorite Ions, and Hypochlorous Acid as Key Intermediates of the Autocatalytic Chlorine Dioxide-Thiourea Dioxide Reaction
Hu, Ying,Horváth, Attila K.,Duan, Sasa,Csek?, Gy?rgy,Makarov, Sergei V.,Gao, Qingyu
, p. 5011 - 5020 (2015)
The kinetics of the chlorine dioxide-thiourea dioxide reaction was investigated by monitoring absorbance-time profiles at λ = 360 nm. Under acidic conditions, the primary carbon-containing product is cyanamide, not urea as considered previously for many oxidation reactions of thiourea dioxide. Increase of the rate of the reaction by an increase of pH can be readily explained by the slow pH-dependent formation of a more reactive form of thiourea dioxide (TDO) that is produced steadily and unavoidably as the stock TDO solution ages. We have also found that the absorbance-time profiles of the chlorine dioxide-TDO reaction are sigmoidal with excess TDO. The addition of methionine as a hypochlorous acid scavenging agent inhibits the reaction significantly, whereas the addition of chlorite ions and trace amounts of hydrogen sulfite ions accelerates the decay of chlorine dioxide. On the basis of these experiments, a sixteen-step kinetic model involving hypochlorous acid, chlorite ions, and hydrogen sulfite ions as key intermediates that provide an autocatalytic cycle is proposed to account for the overall kinetic behavior observed, including the slow rearrangement of TDO.
Electrooxidation of Formamidine Disulfide Simultaneously Investigated by On-Line High Performance Liquid Chromatography and Cyclic Voltammetry
Feng, Na,Li, Fengli,Liu, Yang,Luo, Hainan,Zhang, Baoying,Zhang, Wei,Zhao, Yuyan
, p. 1074 - 1080 (2021/11/03)
The electro-oxidation of formamidine disulfide, an important sulfur-containing compound, was simultaneously investigated with on-line high-performance liquid chromatography and cyclic voltammetry. Using a home-made microporous sampler located at the electrode interface, the solution on the electrode surface was in situ sampled and analyzed. The electrochemical scanning was synchronously performed, which allowed the electro-oxidation products to be detected at a given potential. The main products on the surface of platinum electrode were found to be thiourea, formamidine sulfinic acid, cyanamide, and elemental sulfur. Forced convection arising from the sampling played an important role in the electrochemical oxidation. The extraction of electrode surface solution promoted the renewal of reactant and its intermediates, which induced the change of cyclic voltammetry curve. The forced convection also contributed to the redox peak current of the species on the cyclic voltammetry curves through the change of concentration of reactant and its intermediates. This technique can help to explore the reaction mechanism of complex electrochemical reactions.
Photoredox chemistry in the synthesis of 2-aminoazoles implicated in prebiotic nucleic acid synthesis
Liu, Ziwei,Wu, Long-Fei,Bond, Andrew D.,Sutherland, John D.
supporting information, p. 13563 - 13566 (2020/11/17)
Prebiotically plausible ferrocyanide-ferricyanide photoredox cycling oxidatively converts thiourea to cyanamide, whilst HCN is reductively homologated to intermediates which either react directly with the cyanamide giving 2-aminoazoles, or have the potential to do so upon loss of HCN from the system. Thiourea itself is produced by heating ammonium thiocyanate, a product of the reaction of HCN and hydrogen sulfide under UV irradiation. This journal is
MOF-Derived Cu-Nanoparticle Embedded in Porous Carbon for the Efficient Hydrogenation of Nitroaromatic Compounds
Qiao, Chenxia,Jia, Wenlan,Zhong, Qiming,Liu, Bingyu,Zhang, Yifu,Meng, Changgong,Tian, Fuping
, p. 3394 - 3401 (2020/05/19)
Abstract: Novel Cu-nanoparticles (NPs) embedded in porous carbon materials (Cu@C-x) were prepared by one-pot pyrolysis of metal–organic frameworks (MOF) HKUST-1 at different temperatures. The obtained material Cu@C-x was used as a cost-effective catalyst for the hydrogenation of nitrobenzene using NaBH4 as the reducing agent under mild reaction conditions. By considering the catalyst preparation and the catalytic activity, a pyrolysis temperature of 400?°C was finally chosen to synthesize the optimal catalyst. When the aromatic nitro compounds with reducible groups, such as cyano, halogen, and alkyl groups, were tested in this catalytic hydrogenation, an excellent selectivity approaching 100% was achieved. In the recycling experiment, a significant decrease in nitrobenzene conversion was observed in the third cycle, mainly due to the very small amount of catalyst employed in the reaction. Hence, the easily prepared and cost-effective Cu@C-400 catalyst fabricated in this study demonstrates potential for the applications in selective reduction of aromatic nitro compounds. Graphic Abstract: The catalyst Cu@C-400 exhibited 100?% conversion and high selectivity for the hydrogenation of industrially relevant nitroarenes.[Figure not available: see fulltext.].
A Facile Synthesis of Pd–C3N4@Titanate Nanotube Catalyst: Highly Efficient in Mizoroki–Heck, Suzuki–Miyaura C–C Couplings
Velpula, Venkata Ramana Kumar,Ketike, Thirupathaiah,Paleti, Gidyonu,Kamaraju, Seetha Rama Rao,Burri, David Raju
, p. 95 - 105 (2019/11/03)
Abstract: A Pd–C3N4@titanate nanotube (Pd–C3N4@TNT) catalyst workable in water medium, robust against leaching and agglomeration was prepared in a facile synthetic procedure using quite common chemicals such as TiO2 powder, urea and palladium acetate. The Pd–C3N4@TNT catalyst has been characterized by BET surface area and pore size distribution, X-ray diffraction, solid-state 13C NMR spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The Pd–C3N4@TNT is a green catalyst for the Miziroki–Heck and Suzuki–Miyaura C–C coupling reactions in water medium with high efficiency (??99% product yields) due to atomic level immobilization of Pd in C3N4 networked titanate nanotubes. Pd–C3N4@TNT is robust against leaching and agglomeration due to stable and furthermore it is recyclable and usable at least for five repeated cycles. The use of water as solvent, absence of leaching and agglomeration, recyclability and reusability ascertains the greenness of Pd–C3N4@TNT) catalyst and process. Graphic Abstract: Novel Pd–C3N4@titanate nanotube catalyst prepared from bulk TiO2 and urea by simple hydrothermal and thermal pyrolysis followed by immobilization of Pd is active and selective for Mizoroki–Heck, Suzuki–Miyaura C–C couplings in water medium.[Figure not available: see fulltext.].
Synthesis of 5 - amino tetrazole method
-
Paragraph 0028; 0029; 0030, (2019/06/13)
Synthesis of 5 - amino tetrazole method, in order to hydrazine hydrate, lime nitrogen, sodium nitrite, inorganic acid and inorganic base as the obtained 5 - amino tetrazole. The method through the metathesis reaction, addition reaction and diazo isomerization reaction of the cyano lead lime nitrogen into the aminoguanidine, then generating aminoguandine isomerization reaction to synthesize 5 - amino tetrazole. The invention compared with the traditional method, has the following advantages: (1) price cheap raw materials as the starting raw material, synthetic product is obtained; (2) simplified 5 - amino tetrazole operation process, reduce the reaction solvent types and process the complexity of the operation, reduces the cost of material and production cost, reduces the 5 - amino tetrazole synthesis cost of, improve the market competitiveness of the product. It has high efficiency, high yield, low cost, easy operation and the like.
The synthesis of arylcyanamides: A copper-catalyzed consecutive desulfurization and C-N cross-coupling strategy
Boddapati, S. N. Murthy,Polam, Naresh,Mutchu, Baby Ramana,Bollikolla, Hari Babu
supporting information, p. 918 - 922 (2018/02/03)
A one pot highly efficient and simple protocol for the construction of aromatic cyanamides from thiourea via desulphurization/C-N cross coupling using a cheap, readily available and air stable copper source as a catalyst has been described. Various iodobenzenes could give their respective C-N cross-coupled products in good to excellent yields under optimized reaction conditions. Further, the substrate scope has been explored.
The synthesis of aryl cyanamides through C-N cross-coupling
Kondraganti, Lakshmi,Manabolu, Surendra Babu,Dittakavi, Rama Chandran
, p. 629 - 634 (2020/06/26)
The methodology for the preparation of aromatic cyanamides has been demonstrated. The present method involves consecutive desulphurization/C-N cross-coupling reaction. Cheap, readily available and air stable cobalt catalyst has been used for this methodology. In addition, the substrate scope has been explored.
Flow-Tube Investigations of Hypergolic Reactions of a Dicyanamide Ionic Liquid Via Tunable Vacuum Ultraviolet Aerosol Mass Spectrometry
Chambreau, Steven D.,Koh, Christine J.,Popolan-Vaida, Denisia M.,Gallegos, Christopher J.,Hooper, Justin B.,Bedrov, Dmitry,Vaghjiani, Ghanshyam L.,Leone, Stephen R.
, p. 8011 - 8023 (2016/10/31)
The unusually high heats of vaporization of room-temperature ionic liquids (RTILs) complicate the utilization of thermal evaporation to study ionic liquid reactivity. Although effusion of RTILs into a reaction flow-tube or mass spectrometer is possible, competition between vaporization and thermal decomposition of the RTIL can greatly increase the complexity of the observed reaction products. In order to investigate the reaction kinetics of a hypergolic RTIL, 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-) was aerosolized and reacted with gaseous nitric acid, and the products were monitored via tunable vacuum ultraviolet photoionization time-of-flight mass spectrometry at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Reaction product formation at m/z 42, 43, 44, 67, 85, 126, and higher masses was observed as a function of HNO3 exposure. The identities of the product species were assigned to the masses on the basis of their ionization energies. The observed exposure profile of the m/z 67 signal suggests that the excess gaseous HNO3 initiates rapid reactions near the surface of the RTIL aerosol. Nonreactive molecular dynamics simulations support this observation, suggesting that diffusion within the particle may be a limiting step. The mechanism is consistent with previous reports that nitric acid forms protonated dicyanamide species in the first step of the reaction.
Photochemistry of 1- and 2-Methyl-5-aminotetrazoles: Structural Effects on Reaction Pathways
Ismael,Fausto,Cristiano
, p. 11656 - 11663 (2016/12/09)
The influence of the position of the methyl substituent in 1- and 2-methyl-substituted 5-aminotetrazoles on the photochemistry of these molecules is evaluated. The two compounds were isolated in an argon matrix (15 K) and the matrix was subjected to in situ narrowband UV excitation at different wavelengths, which induce selectively photochemical transformations of different species (reactants and initially formed photoproducts). The progress of the reactions was followed by infrared spectroscopy, supported by quantum chemical calculations. It is shown that the photochemistries of the two isomers, 1-methyl-(1H)-tetrazole-5-amine (1a) and 2-methyl-(2H)-tetrazole-5-amine (1b), although resulting in a common intermediate diazirine 3, which undergoes subsequent photoconversion into 1-amino-3-methylcarbodiimide (H2N-N=C=N-CH3), show marked differences: formation of the amino cyanamide 4 (H2N-N(CH3)-C=N) is only observed from the photocleavage of the isomer 1a, whereas formation of the nitrile imine 2 (H2N-C-=N+=N-CH3) is only obtained from photolysis of 1b. The exclusive formation of nitrile imine from the isomer 1b points to the possibility that only the 2H-tetrazoles forms can give a direct access to nitrile imines, while observation of the amino cyanamide 4 represents a novel reaction pathway in the photochemistry of tetrazoles and seems to be characteristic of 1H-tetrazoles. The structural and vibrational characterization of both reactants and photoproducts has been undertaken.
