106-42-3

Basic information

• Product Name: 1,4-Dimethylbenzene
• Synonyms: p-Xylene(8CI);1,4-Xylene;4-Methyltoluene;NSC 72419;p-Dimethylbenzene;p-Methyltoluene;p-Phenylenebis(methylene);p-Xylol;1,4-Dimethylbenzene
• CAS NO: 106-42-3
• Molecular Formula: C₈H₁₀
• Molecular Weight: 106.1674
• EINECS: 203-396-5
• Product Categories: Industrial/Fine Chemicals;Analytical Chemistry;Standard Solution of Volatile Organic Compounds for Water & Soil Analysis;Standard Solutions (VOC);Amber Glass Bottles;Analytical Reagents;Analytical/Chromatography;CHROMASOLV for HPLC;Chromatography Reagents &;HPLC &;HPLC Grade Solvents (CHROMASOLV);HPLC/UHPLC Solvents (CHROMASOLV);Solvent Bottles;Solvent by Application;Solvent Packaging Options;Solvents;UHPLC Solvents (CHROMASOLV)
• Mol File: 106-42-3.mol
• Article Data: 532

Chemical Properties

• Melting Point: 13-13℃
• Boiling Point: 139.61 °C at 760 mmHg
• Flash Point: 27.22 °C
• Appearance: colourless liquid
• Density: 0.87 g/cm³
• Vapor Density: 3.7 (vs air)
• Vapor Pressure: 7.943mmHg at 25°C
• Refractive Index: n20/D 1.495(lit.)
• Storage Temp.: 0-6°C
• Solubility: water: soluble0.2g/L
• PKA: >15 (Christensen et al., 1975)
• Water Solubility: Miscible with alcohol, ether, acetone, benzene and chloroform. Immiscible with water.
• Stability: Stable. Incompatible with oxidizing agents. Hygroscopic. Flammable.
• Merck: 14,10081
• BRN: 1901563
• CAS DataBase Reference: 1,4-Dimethylbenzene(CAS DataBase Reference)
• NIST Chemistry Reference: 1,4-Dimethylbenzene(106-42-3)
• EPA Substance Registry System: 1,4-Dimethylbenzene(106-42-3)

Safety Data

• Hazard Codes: Xn:Harmful
• Statements: R10:Flammable.; R20/21:Harmful by inhalation and in contact with skin.; R38:Irritating to skin.
• Safety Statements: S25:Avoid contact with eyes.
• RIDADR: UN 1307 3/PG 3
• WGK Germany: 2
• RTECS: ZE2625000
• TSCA: Yes
• HazardClass: 3
• PackingGroup: III
• Hazardous Substances Data: 106-42-3(Hazardous Substances Data)

Usage

Description

p-xylene is an aromatic hydrocarbon based on benzene with two methyl substituents with the chemical formula C8H10 or C6H4(CH3)2. It is one of the three isomers of dimethylbenzene known collectively as xylenes. The “p” stands for para, identifying that he two methyl groups in p-xylene occupy the diametrically opposite substituent positions 1 and 4. p-Xylene is a colorless, flammable liquid practically insoluble in water. p-Xylene is a colorless watery liquid with a sweet odor and is dangerously flammable, with a flash point of 27°C. p-Xylene is widely used as a feedstock (or “building block”) to manufacture other industrial chemicals, notably terephthalic acid (TPA), purified terephthalic acid (PTA) and dimethyl-terephthalate (DMT). It also may be polymerised directly to produce parylene.

References

1.https://en.wikipedia.org/wiki/P-Xylene 2.https://pubchem.ncbi.nlm.nih.gov/compound/p-xylene#section=Top 3.https://www.chemicalsafetyfacts.org/paraxylene/

Chemical Properties

colourless liquid

Physical properties

Clear, colorless, watery liquid with a sweet odor. Odor threshold concentrations reported in air were 47 ppbv by Leonardos et al. (1969) and 58 ppbv by Nagata and Takeuchi (1990).

Uses

Different sources of media describe the Uses of 106-42-3 differently. You can refer to the following data:
1. Xylene occurs in petroleum solvents andgasoline. The widest applications of xyleneare as solvents in paints, coatings, and rubber.Xylene isomers are used in the manufacture ofdyes, drugs, pesticides, and in many organicintermediates, such as terephthalic acid andphthalic anhydride.
2. p-Xylene is used as a precursor in the production of benzoic, isophthalic, tetraphillic acids and dimethyle esters, which are used in the manufacture of polyester. It acts as an intermediate in plastic and rubber products.
3. As solvent; raw material for production of benzoic acid, phthalic anhydride, isophthalic and terephthalic acids as well as their dimethyl esters used in the manufacture of polyester fibers; manufacture of dyes and other organics; sterilizing catgut; with Canada balsam as oil-immersion in microscopy; clearing agent in microscope technique.

Definition

ChEBI: A xylene with methyl groups at positions 1 and 4.

Synthesis Reference(s)

The Journal of Organic Chemistry, 53, p. 3247, 1988 DOI: 10.1021/jo00249a020Tetrahedron Letters, 26, p. 1935, 1985 DOI: 10.1016/S0040-4039(00)98345-X

General Description

A colorless watery liquid with a sweet odor. Less dense than water. Insoluble in water. Irritating vapor. Freezing point is 56°F.

Air & Water Reactions

Highly flammable. Insoluble in water.

Reactivity Profile

P-XYLENE may react with oxidizing materials. . Acetic acid forms explosive mixtures with P-XYLENE and air (Shraer, B.I. 1970. Khim. Prom. 46(10):747-750.).

Health Hazard

Different sources of media describe the Health Hazard of 106-42-3 differently. You can refer to the following data:
1. Vapors cause headache and dizziness. Liquid irritates eyes and skin. If taken into lungs, causes severe coughing, distress, and rapidly developing pulmonary edema. If ingested, causes nausea, vomiting, cramps, headache, and coma. Can be fatal. Kidney and liver damage can occur.
2. The toxic properties of xylene isomers aresimilar to toluene or ethylbenzene. The targetorgans are the central nervous system, eyes,gastrointestinal tract, kidneys, liver, blood,and skin, which, however, are affected onlyat high levels of exposure. In humans itsexposure may cause irritation of the eyes,nose, and throat, headache, dizziness, excitement,drowsiness, nausea, vomiting, abdominalpain, and dermatitis. The irritation effectsin humans may be felt at a concentration of200 ppm in air, while exposure to 10,000 ppmfor 6–8 hours may be fatal.The oral toxicity of xylene is low. Ingestionof a high dose, however, can causedepression of the central nervous system,dizziness, nausea, and vomiting and abdominalpain. The oral LD50 values in ratsfor xylene isomers are within the range of5000 mg/kg.The major route of absorption of xyleneis inhalation. Another significant route isskin absorption of the liquid. About 5% ofabsorbed xylene is excreted unchanged inexpired air within a few hours, while less than2% is hydroxylated to xylenols. Over 90% ofabsorbed xylenes are metabolized to o-, m-,and p-isomers of methyl benzoic acid andexcreted in urine as methyl hippuric acids(ACGIH 1986). Small amounts of xylenesmay remain stored in adipose tissue. Repeatedexposures may cause accumulation in theblood.

Fire Hazard

Behavior in Fire: Vapor is heavier than air and may travel considerable distance to a source of ignition and flash back.

Flammability and Explosibility

Flammable

Chemical Reactivity

Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.

Safety Profile

Moderately toxic by intraperitoneal route. Mildly toxic by ingestion and inhalation. An experimental teratogen. Experimental reproductive effects. May be narcotic in hgh concentrations. Chronic toxicity not established, but is less toxic than benzene. A very dangerous fire hazard when exposed to heat or flame; can react with oxidzing materials. Explosive in the form of vapor when exposed to heat or flame. To fight fire, use foam, CO2, dry chemical. Potentially explosive reaction with acetic acid + air, 1,3-dichloro-5,5-dimethyl-2,4- imidazolidinhone, nitric acid + pressure. When heated to decomposition it emits acrid smoke and irritating fumes. See also other xylene entries.

Source

Detected in distilled water-soluble fractions No. 2 fuel oil (1.11 mg/L), jet fuel A (1.23 mg/L), diesel fuel (0.56 mg/L), and military jet fuel JP-4 (5.48 mg/L) (Potter, 1996); in new and used motor oil at concentrations of 0.26 to 0.29 and 302 to 339 μg/L, respectively (Chen et al., 1994). The average volume percent and estimated mole fraction in American Petroleum Institute PS-6 gasoline are 1.809 and 0.02263, respectively (Poulsen et al., 1992). Diesel fuel obtained from a service station in Schlieren, Switzerland contained m/p-xylene at a concentration of 336 mg/L (Schluep et al., 2001). Thomas and Delfino (1991) equilibrated contaminant-free groundwater collected from Gainesville, FL with individual fractions of three individual petroleum products at 24–25 °C for 24 h. The aqueous phase was analyzed for organic compounds via U.S. EPA approved test method 602. Average m+p-xylene concentrations reported in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were 8.611, 0.658, and 0.228 mg/L, respectively. When the authors analyzed the aqueous-phase via U.S. EPA approved test method 610, average m+p-xylene concentrations in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were lower, i.e., 6.068, 0.360, and 0.222 mg/L, respectively. Based on laboratory analysis of 7 coal tar samples, m+p-xylene concentrations ranged from ND to 6,000 ppm (EPRI, 1990). Detected in 1-yr aged coal tar film and bulk coal tar at concentrations of 260 and 830 mg/kg, respectively (Nelson et al., 1996). A high-temperature coal tar contained pxylene at an average concentration of 0.03 wt % (McNeil, 1983). Schauer et al. (2001) measured organic compound emission rates for volatile organic compounds, gas-phase semi-volatile organic compounds, and particle-phase organic compounds from the residential (fireplace) combustion of pine, oak, and eucalyptus. The gas-phase emission rate of m-xylene + p-xylene was 60.0 mg/kg of pine burned. Emission rates of both isomers were not measured during the combustion of oak and eucalyptus. Drinking water standard (final): For all xylenes, the MCLG and MCL are both 10 mg/L. In addition, a DWEL of 70 mg/L was recommended (U.S. EPA, 2000).

Environmental fate

Biological. Microbial degradation of p-xylene produced 4-methylbenzyl alcohol, pmethylbenzaldehyde, p-toluic acid, and 4-methylcatechol (quoted, Verschueren, 1983). Dimethylcis, cis-muconic acid, and 2,3-dihydroxy-p-toluic acid were reported to be biooxidation products of p-xylene by Nocardia corallina V-49 using n-hexadecane as the substrate (Keck et al., 1989). Reported biodegradation products of the commercial product containing xylene include α-hydroxy-p-toluic acid, p-methylbenzyl alcohol, benzyl alcohol, 4-methylcatechol, m- and ptoluic acids (Fishbein, 1985). It was reported that p-xylene was cometabolized resulting in the formation of p-toluic and 2,3-dihydroxy-o-toluic acids (Pitter and Chudoba, 1990). In anoxic groundwater near Bemidji, MI, p-xylene anaerobically biodegraded to the intermediate p-toluic acid (Cozzarelli et al., 1990). In gasoline-contaminated groundwater, methylbenzylsuccinic acid was identified as the first intermediate during the anaerobic degradation of xylenes (Reusser and Field, 2002). Photolytic. A n-hexane solution containing m-xylene and spread as a thin film (4 mm) on cold water (10 °C) was irradiated by a mercury medium pressure lamp. In 3 h, 18.5% of the p-xylene photooxidized into p-methylbenzaldehyde, p-benzyl alcohol, p-benzoic acid, and pmethylacetophenone (Moza and Feicht, 1989). Glyoxal and methylglyoxal were produced from the photooxidation of p-xylene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of p-xylene and OH radicals at room temperature was 1.22 x 10-11 cm3/molecule?sec (Hansen et al., 1975). A rate constant of 7.45 x 10-9 L/molecule?sec was reported for the reaction of p-xylene with OH radicals in the gas phase (Darnall et al., 1976). Similarly, a room temperature rate constant of 1.41 x 10-11 cm3/molecule?sec was reported for the vapor-phase reaction of p-xylene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 1.29 x 10-11 cm3/molecule?sec was reported for the same reaction (Ohta and Ohyama, 1985). Chemical/Physical. Under atmospheric conditions, the gas-phase reaction with OH radicals and nitrogen oxides resulted in the formation of p-tolualdehyde (Atkinson, 1990). Kanno et al. (1982) studied the aqueous reaction of p-xylene and other aromatic hydrocarbons (benzene, toluene, oand m-xylene, and naphthalene) with hypochlorous acid in the presence of ammonium ion. They reported that the aromatic ring was not chlorinated as expected but was cleaved by chloramine forming cyanogen chloride. The amount of cyanogen chloride formed increased at lower pHs (Kanno et al., 1982). Products identified from the OH radical-initiated reaction of p-xylene in the presence of nitrogen dioxide were 3-hexene-2,5-dione, p-tolualdehyde, and 2,5-dimethylphenol (Bethel et al., 2000).

Purification Methods

The general purification methods listed for xylene above are applicable. p-Xylene can readily be separated from its isomers by crystallisation from such solvents as MeOH, EtOH, isopropanol, acetone, butanone, toluene, pentane or pentene. It can be further purified by fractional crystallisation by partial freezing, and stored over sodium wire or molecular sieves Linde type 4A. [Stokes & French J Chem Soc, Faraday Trans 1 76 537 1980, Beilstein 5 H 382, 5 I 185, 5 II 296, 5 III 845, 5 IV 951.]

InChI:InChI:1S/C8H10/c1-7-3-5-8(2)6-4-7/h3-6H,1-2H3

Synthetic route

4-methyl-benzaldehyde (104-87-0) → para-xylene (106-42-3)

Conditions	Yield
With hydrogen In water; ethyl acetate at 50℃; under 15001.5 Torr; for 5h;	99%
With hydrogen In water at 25℃; for 1h;	99%
With hydrogen at 350℃; under 760.051 Torr;	95%

ethene (74-85-1) + 2,5-hexanedione (110-13-4) → para-xylene (106-42-3)

Conditions	Yield
With solid acid catalyst tin phosphate In n-heptane at 300℃; under 15001.5 Torr; for 12h; Reagent/catalyst; Solvent; Pressure; Temperature;	90%
With copper(II) bis(trifluoromethanesulfonate) at 250 - 270℃; under 26892.4 - 82745.9 Torr; for 5h; Inert atmosphere;	44%

2,5-dimethylfuran (625-86-5) + ethene (74-85-1) → para-xylene (106-42-3)

Conditions	Yield
With P-containing zeolite Beta In n-heptane at 250℃; under 46504.7 Torr; Reagent/catalyst; Diels-Alder Cycloaddition;	97%
With benzoic acid anhydride In acetic acid at 280℃; under 63006.3 Torr; for 8h; Pressure; Reagent/catalyst; Solvent; Temperature; Time;	92.3%
With copper(II) bis(trifluoromethanesulfonate) In tetrahydrofuran at 270℃; under 26892.4 - 82745.9 Torr; for 5h; Catalytic behavior; Reagent/catalyst; Solvent; Inert atmosphere;	91%

2,5-dimethylfuran (625-86-5) + ethene (74-85-1) → para-xylene (106-42-3) + 2,5-hexanedione (110-13-4)

Conditions	Yield
In n-heptane at 249.84℃; under 37503.8 Torr; for 24h; Reagent/catalyst; Autoclave; Inert atmosphere;	A 75% B n/a
In acetic acid at 280℃; under 63006.3 Torr; for 4h; Pressure; Reagent/catalyst; Solvent; Temperature; Time;	A 68.5% B 12.1%
With Sn-BEA In n-heptane at 250℃; under 46504.7 Torr; for 24h; Catalytic behavior; Kinetics; Diels-Alder Cycloaddition; Autoclave; Inert atmosphere; chemoselective reaction;	A 43% B n/a

methanol (67-56-1) + toluene (108-88-3) → o-xylene (95-47-6) + para-xylene (106-42-3) + m-xylene (108-38-3)

Conditions	Yield
With hydrogen; P-modified ZSM-5 In water at 480 - 485℃; under 1794.37 Torr; for 23.53h; Product distribution / selectivity;	A n/a B 15.54% C n/a
H-ZSM-5(73) at 400℃; Product distribution; further catalysts (alumosilicates, modified zeolites);
Na(+)x(Mg3)(Si(4-x)Alx)O10(OH)2 at 349.9℃; for 1h; Product distribution; various pillared clays and zeolites as catalysts;

methanol (67-56-1) + toluene (108-88-3) → para-xylene (106-42-3)

Conditions	Yield
With hydrogen In water at 400℃; under 3750.38 Torr; Reagent/catalyst; Pressure; Temperature; Concentration; Inert atmosphere;	29.3%
With hydrogen at 250℃; Kinetics; Thermodynamic data; Further Variations:; pH-values;
silica bound HZSM-5 zeolite at 600℃; under 3620.13 - 4137.29 Torr; for 3.25 - 7.5h; Conversion of starting material;

4-Methylbenzyl alcohol (589-18-4) + benzamide (55-21-0) → para-xylene (106-42-3) + N-(p-methylbenzyl)benzamide (65608-94-8)

Conditions	Yield
With barium trifluoromethanesulfonate In toluene at 150℃; for 18h; Reagent/catalyst; Glovebox; Inert atmosphere;	A 29% B 72%

o-xylene (95-47-6) + m-xylene (108-38-3) → para-xylene (106-42-3)

Conditions	Yield
With hydrogen; silicate ITQ-13, aluminium form at 360℃; under 10343.2 Torr; Product distribution / selectivity; fixed-bed downflow reactor;	23.5%
MTW-zeolite/Al2O3 (Catalyst B) at 280℃; under 26618.1 Torr; Conversion of starting material; Liquid phase;
Ga-MFI zeolite/ZrO2/Al2O3 (Catalyst C) at 300℃; under 26618.1 Torr; Conversion of starting material; Liquid phase;

2,5-dimethylfuran (625-86-5) + ethene (74-85-1) → para-xylene (106-42-3) + 3,6-dimethylcyclohex-2-enone (15329-10-9) + 2,5-hexanedione (110-13-4)

Conditions	Yield
With H-BEA-25 In 1,4-dioxane at 249.84℃; under 15001.5 Torr; for 4h; Diels-Alder Cycloaddition; Autoclave; chemoselective reaction;

1,4-dimethylcyclohex-1-ene (2808-79-9) → para-xylene (106-42-3)

Conditions	Yield
With palladium on activated charcoal In toluene at 130℃; under 7500.75 - 30003 Torr; for 3h; Autoclave;

1,4-dimethyl-7-oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic acid anhydride (111957-97-2) → 3,6-dimethyl phthalic anhydride (5463-50-3) + para-xylene (106-42-3)

Conditions	Yield
With zeolite Y with a silica-alumina at 200℃; for 2h; Temperature; Inert atmosphere;	A 72% B 17%
With 1 wtpercent Pd/C loaded on zeolite H-Y with a silica-alumina ratio of 40 In toluene at 200℃; under 750.075 Torr; for 4h; Inert atmosphere;

4-Methylbenzyl alcohol (589-18-4) + benzamide (55-21-0) → para-xylene (106-42-3) + N-(p-methylbenzyl)benzamide (65608-94-8) + N,N′‑(4‑methylbenzylidene)bisbenzamide (40891-10-9)

Conditions	Yield
With indium sulfate In toluene at 150℃; for 18h; Glovebox; Inert atmosphere;	A 60% B 14% C 40%
With zinc(II) sulfate In toluene at 150℃; for 18h; Glovebox; Inert atmosphere;	A 41% B 58% C 6%
With zinc(II) chloride In toluene at 150℃; for 18h; Glovebox; Inert atmosphere;	A 47% B 42% C 21%

ethylbenzene (100-41-4) → para-xylene (106-42-3)

Conditions	Yield
With hydrogen at 480℃; under 8826.09 Torr; Leiten ueber Platin/Aluminiumoxid-Siliciumdioxid;
With hydrogen; 0.3 wtpercent Pt/0.1 wtpercent S/100 wtpercent MTW-zeolite (Catatalyst C) at 370 - 375℃; under 4650.47 Torr; Conversion of starting material;
With hydrogen; 0.3 wtpercent Pt/0.1 wtpercent S/50 wtpercent MTW/50 wtpercent mordenite (Catalyst F) at 370 - 375℃; under 4650.47 Torr; Conversion of starting material;

methanol (67-56-1) + toluene (108-88-3) + benzene (71-43-2) → o-xylene (95-47-6) + para-xylene (106-42-3) + m-xylene (108-38-3)

Conditions	Yield
With hydrogen; 1/16 inch extrudates which contained 65 weight percent H-ZSM-5 and 35 weight percent silica binder at 371.101℃; under 3309.83 Torr;
With hydrogen; 1/16 inch extrudates which contained 65 wt. percent H-ZSM-23 having a silica to alumina mole ratio of 110:1 and 35 wt. percent of alumina binder at 499.99℃; under 7757.43 Torr;
With hydrogen; SAPO-11 at 499.99℃; under 7757.43 Torr;

methanol (67-56-1) + toluene (108-88-3) + benzene (71-43-2) → para-xylene (106-42-3)

Conditions	Yield
With hydrogen; silica selectivated ZSM-5 at 371.101℃; under 10343.2 Torr;

4-methyl-benzaldehyde (104-87-0) → 4-Methylbenzyl alcohol (589-18-4) + para-xylene (106-42-3)

Conditions	Yield
With triethylsilane; palladium dichloride In ethanol for 0.5h; Inert atmosphere;	A 10.0 %Chromat. B 88.5 %Chromat.
With palladium on silica; hydrogen In dodecane at 190℃; under 22502.3 Torr; for 5h;
With palladium on activated charcoal; hydrogen In water at 100℃; for 10h; chemoselective reaction;	A 40 %Chromat. B 60 %Chromat.

m-xylene (108-38-3) → o-xylene (95-47-6) + para-xylene (106-42-3)

Conditions	Yield
With parent microporous ZSM-5 zeolite at 250℃; for 0.25h; Reagent/catalyst;	A 27% B 10%
With hydrogen; H-ZSM-5 at 349.9℃; under 15001.2 Torr; Product distribution; further catalysts, variation of temperature;
CVD boria-alumina at 450℃; Product distribution; dependence of conversion on B2O3 content of catalyst;

para-chlorotoluene (106-43-4) + bis{μ-[2-(dimethylamino)ethanolato-N,O:O]}tetramethyldialuminum → para-xylene (106-42-3)

Conditions	Yield
With tri-tert-butyl phosphine; {MoPdcp[μ-(CO)2][μ3-(CO)](PPh3)}2 In benzene at 120℃; for 15h;	98%

toluene (108-88-3) → para-xylene (106-42-3) + benzene (71-43-2)

Conditions	Yield
With hydrogen; platinum-containing ZSM-5 molecular sieve catalyst at 420℃; under 11251.1 Torr;
With hydrogen; alumina-phosphate-bound MFI catalyst at 560℃; under 18376.8 Torr; Gas phase;
With hydrogen; alumina-phosphate-bound MFI catalyst at 560℃; under 18376.8 Torr; Gas phase;

4-Methylbenzyl alcohol (589-18-4) + benzamide (55-21-0) → para-xylene (106-42-3) + N-(p-methylbenzyl)benzamide (65608-94-8) + bis(4-methylbenzyl) ether (38460-98-9)

Conditions	Yield
With tin(II) trifluoromethanesulfonate In toluene at 150℃; for 18h; Glovebox; Inert atmosphere;	A 8% B 33% C 50%
With zinc trifluoromethanesulfonate In toluene at 150℃; for 18h; Reagent/catalyst; Glovebox; Inert atmosphere;	A 33% B 22% C 21%

2,5-dimethylfuran (625-86-5) + ethene (74-85-1) → para-xylene (106-42-3) + p-n-propyltoluene (1074-55-1) + 2-ethyl-p-xylene (1758-88-9)

Conditions	Yield
With palladium-decorated gold nanoparticles anchored on amphoteric zirconia In n-heptane at 300℃; under 30402 Torr; for 6h;

2,5-dimethylfuran (625-86-5) + ethene (74-85-1) → 4,4-dimethylcyclohexenone (1073-13-8) + para-xylene (106-42-3) + 3,6-dimethylcyclohex-2-enone (15329-10-9)

Conditions	Yield
With Sn-BEA In n-heptane at 275℃; under 30402 Torr; for 1h;

triplal (854432-99-8) → para-xylene (106-42-3) + 1,2,4-Trimethylbenzene (95-63-6)

Conditions	Yield
With palladium/alumina; hydrogen In hexane at 325℃; Flow reactor; Green chemistry;	A 84.8% B 6.5%
With hydrogen In hexane at 325℃; Flow reactor; Green chemistry;	A 19.5% B 73.2%

4-Methylbenzyl chloride (104-82-5) → para-xylene (106-42-3) + 1,2-di-p-tolylethane (538-39-6)

Conditions	Yield
With copper nickel; pyrographite In 1,2-dimethoxyethane at 85℃; for 20h;	A 10% B 90%
With nickel In 1,2-dimethoxyethane for 2h; Ambient temperature;	A 20% B 76%
With magnesium at 600℃;	A 23% B 60%
With water; naphthalen-1-yl-lithium In tetrahydrofuran; diethyl ether; Petroleum ether at -95℃; for 0.75h; Title compound not separated from byproducts;	A 64 % Chromat. B 36 % Chromat.

methanol (67-56-1) + toluene (108-88-3) → para-xylene (106-42-3) + m-xylene (108-38-3)

Conditions	Yield
With Ga2O3 zeolite; silica gel In gas at 400℃; Product distribution; var. catalyst, var. temp.;
With hydrogen; Catalyst G (prepared from NH4-ZSM-5 and H3PO4) at 200 - 500℃; under 1034.32 Torr; Product distribution / selectivity;
With hydrogen; Catalyst H (prepared from NH4-ZSM-5 and H3PO4) at 200 - 500℃; under 1034.32 Torr; Product distribution / selectivity;

carbon monoxide (201230-82-2) + p-xylylene glycol (589-29-7) → para-xylene (106-42-3) + 1,4-phenylenediacetic acid (7325-46-4) + 4-tolylacetic acid (622-47-9)

Conditions	Yield
With hydrogen iodide; tetrakis(triphenylphosphine) palladium(0) In acetone at 90℃; under 68400 Torr; for 42h; Carbonylation; reduction;	A n/a B 48% C 16%

methanol (67-56-1) + toluene (108-88-3) + benzene (71-43-2) → o-xylene (95-47-6) + para-xylene (106-42-3) + ethylbenzene (100-41-4) + m-xylene (108-38-3)

Conditions	Yield
With hydrogen; silicon-selectivated H-ZSM-5/silica bound at 371.101℃; under 10343.2 Torr;
With hydrogen; zeolite bound zeolite at 371.101℃; under 10343.2 Torr;

o-xylene (95-47-6) + ethylbenzene (100-41-4) + m-xylene (108-38-3) → para-xylene (106-42-3)

Conditions	Yield
catalyst contained 15.0percentw EU-1 zeolite in H form, 84.7percentw Al2O3, 0.3percentw Pt and treated with dimethyldisulphide at 390℃; under 11251.1 Torr; Product distribution / selectivity;
catalyst contained 15.0percentw NU-87 zeolite in H form, 84.7percentw Al2O3, 0.3percentw Pt and treated with dimethyldisulphide at 390℃; under 11251.1 Torr; Product distribution / selectivity;
catalyst contained 8.0percentw EU-1 zeolite in H form, 7.0percentw NU-87 zeolite in H form, 84.7percentw Al2O3, 0.15percentw Pt, 0.15percentw Re and treated with dimethyldisulphide at 390℃; under 11251.1 Torr; Product distribution / selectivity;

4-Methylbenzyl alcohol (589-18-4) → para-xylene (106-42-3)

Conditions	Yield
With palladium dichloride In methanol at 40℃; for 18h; Inert atmosphere; Green chemistry; chemoselective reaction;	99%
Multi-step reaction with 2 steps 1: hydrogen; / 350 °C / 760.05 Torr 2: hydrogen; / 350 °C / 760.05 Torr View Scheme
With formic acid; methanesulfonic acid; 1,2-bis((di-tert-butylphosphoryl)methyl)benzene; palladium(II) acetylacetonate; 1,2-bis[di(t-butyl)phosphinomethyl]benzene In 1,2-dichloro-ethane at 100℃; for 18h; Schlenk technique; Sealed tube; Inert atmosphere;	93 %Chromat.
With 2,4,6-trimethyl-pyridine; 4,4'-dimethoxyphenyl disulfide; iridium(lll) bis[2-(2,4-difluorophenyl)-5-methylpyridine-N,C20]-4,40-di-tert-butyl-2,20-bipyridine hexafluorophosphate; triphenylphosphine In toluene for 24h; Irradiation;	63 %Chromat.

carbon monoxide (201230-82-2) + toluene (108-88-3) → o-xylene (95-47-6) + para-xylene (106-42-3) + m-xylene (108-38-3)

Conditions	Yield
With hydrogen at 400℃; under 24549.5 Torr; Temperature; Flow reactor; Inert atmosphere;

para-xylene (106-42-3) → 4-bromo-m-xylene (553-94-6)

Conditions	Yield
With potassium bromide; sodium nitrite In water; trifluoroacetic acid at 20℃; for 0.16h; Product distribution; under argon;	100%
With oxygen; potassium bromide; sodium nitrite In water; trifluoroacetic acid at 20℃; for 5h; Product distribution;	96%
With sulfuric acid; dihydrogen peroxide; sodium bromide In water at 49.84℃;	94%

para-xylene (106-42-3) → mononitro-p-xylene (89-58-7)

Conditions	Yield
With zeolite ZSM-5-60; Nitrogen dioxide	100%
With nitric acid; sulfuric acid In dichloromethane at 25℃; for 0.7h;	100%
With nitric acid In toluene at 60℃; for 2h;	98%

para-xylene (106-42-3) → 4-methyl-benzaldehyde (104-87-0)

Conditions	Yield
With oxygen; 10-methyl-9-phenylacridin-10-ium perchlorate In chloroform at 24.84℃; for 10h; Oxidation; Pyrolysis; visible light;	100%
With sulfuric acid; 9-mesityl-2,7,10-trimethylacridinium perchlorate; water; oxygen In acetonitrile at 24.84℃; for 1.33333h; Quantum yield; Reagent/catalyst; Irradiation;	100%
With N-hydroxyphthalimide; oxygen; cobalt(II) acetate; acetic acid at 20℃; under 760.051 Torr; chemoselective reaction;	100%

para-xylene (106-42-3) → 4-Methylbenzyl bromide (104-81-4)

Conditions	Yield
With bromine In tetrachloromethane Solvent;	100%
With 2,4,4,6-Tetrabromo-2,5-cyclohexadien-1-one; silica gel for 4.5h; UV-irradiation;	84%
With bromine In tetrachloromethane for 1.5h; Ambient temperature;	83%

para-xylene (106-42-3) → 1,4 dimethylcyclohexane (589-90-2)

Conditions	Yield
With hydrogen; [(norbornadiene)rhodium(I)chloride]2; phosphinated polydiacetylene In n-heptane at 30℃; under 60800 Torr; for 1.5h;	100%
With Ti8O8(14+)*6C8H4O4(2-)*4O(2-)*3.3Li(1+)*0.7Co(2+)*0.7C4H8O*0.7H(1-); hydrogen In neat (no solvent) at 120℃; under 37503.8 Torr; for 18h;	100%
With hydrogen at 150℃; under 2280.15 Torr; for 0.5h; Kinetics; Reagent/catalyst; Temperature;	100%

para-xylene (106-42-3) + benzoyl chloride (98-88-4) → 2,5-dimethylbenzophenone (4044-60-4)

Conditions	Yield
With tris(fluorosulphonyl)methane at 138℃; for 3h;	100%
Hf[N(SO2C8F17)2]4 In various solvent(s) at 120℃; for 3h;	98%
With C4F9SO3H at 138℃; for 5h;	91%

[Cp*Ru(CH3CN)3]OTf (113860-02-9) + para-xylene (106-42-3) → {C5(CH3)5}Ru{C6H4(CH3)2}(1+)*CF3SO3(1-)={(C5(CH3)5)Ru(C6H4(CH3)2)}(CF3SO3)

Conditions	Yield
In tetrahydrofuran byproducts: CH3CN; under N2; addn. of Ru-complex to p-xylene and THF (benzene-free), mixt. stirred (30°C); addn. of hexane, solid filtered, washed twice (hexane), dried (vac.), elem. anal.;	100%

para-xylene (106-42-3) + 3-nitro-benzaldehyde (99-61-6) + allyl-trimethyl-silane (762-72-1) → tetrahydro-4-(2,5-dimethylphenyl)-2,6-bis(3-nitrophenyl)-2H-pyran (1157865-90-1)

Conditions	Yield
With boron trifluoride diethyl etherate at 0 - 20℃; for 2h; Sakurai-Hosomi-Prins-Friedel-Crafts reaction; stereoselective reaction;	100%

para-xylene (106-42-3) + C6H6*C33H30N12S3 (1280197-89-8) → 0.25C8H10*C33H30N12S3

Conditions	Yield
at 40℃; for 480h; Gas phase;	100%

4-tert-Butylbenzyl alcohol (877-65-6) + para-xylene (106-42-3) → 2-(4-(tert-butyl)benzyl)-1,4-dimethylbenzene

Conditions	Yield
With (diethylamino)difluorosulfonium tetrafluoroborate In dichloromethane at 20℃; for 4h; Inert atmosphere;	100%

para-xylene (106-42-3) + (6-bromo-2-methylimidazo[1,2-a]pyridin-3-yl)methanol → 6-bromo-3-[(2,5-dimethylphenyl)methyl]-2-methylimidazo[1,2-a]pyridine

Conditions	Yield
With methanesulfonic acid at 100℃; for 1h;	100%

para-xylene (106-42-3) + 2-bromo-5-chlorobenzyl bromide (66192-24-3) → 2-(2-bromo-5-chlorobenzyl)-1,4-dimethylbenzene

Conditions	Yield
With indium(III) bromide In dichloromethane for 6h; Schlenk technique; Inert atmosphere; Molecular sieve;	100%

para-xylene (106-42-3) → terephthalic acid (100-21-0)

Conditions	Yield
With ammonium acetate; water; hydrogen bromide; oxygen; manganese(II) acetate; cobalt(II) diacetate tetrahydrate; 1-n-butyl-3-methylimidazolim bromide; acetic acid at 200℃; under 30753.1 Torr; for 10h; Time; Temperature; Reagent/catalyst; Concentration; Inert atmosphere;	99.9%
With oxovanadium(IV) sulfate; hydrogen bromide; oxygen; acetic acid In water at 100℃; under 750.075 Torr; for 20h;	98%
With oxygen; acetic acid; hydrogen bromide; cobalt(II) acetate; manganese(II) acetate In water at 200℃; under 22502.3 Torr; for 0.05h; Product distribution / selectivity; Inert atmosphere;	98.3%

para-xylene (106-42-3) → p-Xylylene dichloride (623-25-6)

Conditions	Yield
With chlorine; 3-butyl-1,2-dimethylimidazolium chloride In perfluoroheptane at 84℃; for 3h; Temperature; Solvent;	99.11%
With chlorine; 3-butyl-1,2-dimethylimidazolium chloride at 120℃; for 3h; Reagent/catalyst; Temperature; Ionic liquid; Irradiation;	99.1%
durch Chlorieren;

para-xylene (106-42-3) → p-benzylchloride

Conditions	Yield
Stage #1: para-xylene With 1-dodecyl-3-methylimidazol-1-ium chloride at 110℃; Irradiation; Stage #2: With chlorine at 90 - 120℃; Reagent/catalyst; Temperature; Reflux;	99.11%

1,1-Diphenylmethanol (91-01-0) + para-xylene (106-42-3) → ((2,5-dimethylphenyl)methylene)dibenzene (7249-83-4)

Conditions	Yield
With silica gel supported sodium hydrogen sulfate at 80℃; for 0.5h; Friedel-Crafts type alkylation;	99%
With H5CoW12O40 supported on rice husk ash extracted nano silica at 60℃; for 0.666667h; Reagent/catalyst; Green chemistry;	98%
With Fe3O4/FeO at 60℃; for 0.333333h; Green chemistry;	92%

para-xylene (106-42-3) → p-Toluic acid (99-94-5)

Conditions	Yield
With tert.-butylhydroperoxide; water at 20℃; for 10h; Inert atmosphere;	99%
With N-hydroxy-tetrahydrophthalimide; oxygen; nitric acid at 50℃; under 750.075 - 1500.15 Torr; for 25h; Autoclave; Green chemistry;	91.16%
With MoO(O2)(8-quinolinolate)2; dihydrogen peroxide In acetonitrile for 6h; Oxidation; Heating;	88%

para-xylene (106-42-3) + acetyl chloride (75-36-5) → 1-(2,5-dimethylphenyl)-1-ethanone (2142-73-6)

Conditions	Yield
With aluminum (III) chloride In chloroform at 0 - 20℃; Inert atmosphere;	99%
With aluminum (III) chloride In carbon disulfide at 0 - 20℃; Friedel Crafts acylation; Inert atmosphere;	95%
Friedel-Crafts alkylation;	90%

para-xylene (106-42-3) + benzoic acid anhydride (93-97-0) → 2,5-dimethylbenzophenone (4044-60-4)

Conditions	Yield
sulfated zirconia at 100℃; for 2h; Product distribution; Further Variations:; Catalysts; Friedel-Crafts acylation;	99%
With C4F9SO3H at 138℃; for 5h;	93%

para-xylene (106-42-3) + 1-bromomethyl-4-bromobenzene (589-15-1) → 1,4-dimethyl-2-(4-bromobenzyl)benzene

Conditions	Yield
With indium(III) chloride; 4 A molecular sieve In dichloromethane at 20℃; for 16h; Friedel-Crafts alkylation;	99%
With potassium cyanide; aluminum oxide at 50℃; for 5h;	83 % Chromat.

Upstream product

• 107-39-1 2,4,4-trimethyl-1-pentene 
• 75-44-5 phosgene 
• 60-29-7 diethyl ether 
• 56428-04-7 (4-tert-butyl-benzyl)-(4-methyl-benzyl)-ether 
• 920-39-8 isopropylmagnesium bromide 
• 589-81-1 3-methylheptane 
• 927-98-0 2,5-dimethyl-hexa-1,3t-diene 
• 563-45-1 3-Methyl-1-butene 
• 563-47-3 3-Chloro-2-methylpropene 
• 95-63-6 1,2,4-Trimethylbenzene 
• 108-67-8 1,3,5-trimethyl-benzene 
• 16170-82-4 [14C]methyl iodide 
• 620-83-7 1-methyl-4-(phenylmethyl)benzene 
• 95-47-6 o-xylene 

Downstream Products

• 6165-51-1 1,4-dimethyl-2-(1-phenylethyl)benzene 
• 28591-11-9 4-(2,5-Dimethylphenyl)valeriansaeure 
• 35019-05-7 2,2',5,5'-tetramethyldiphenylmethanone 
• 104-82-5 4-Methylbenzyl chloride 
• 623-25-6 p-Xylylene dichloride 
• 60288-22-4 1,4-dimethyl-2-(o-carboxybenzoyl)benzene 
• 66325-55-1 1,1,3,4,7-pentamethyl-indene 
• 34670-08-1 5-(2,5-dimethylphenyl)-5-oxopentanoic acid 
• 7325-46-4 1,4-phenylenediacetic acid 
• 622-47-9 4-tolylacetic acid 
• 142-62-1 hexanoic acid 
• 4132-72-3 2,5-dimethylisopropylbenzene 
• 589-93-5 2,5-dimethylpyridine 
• 95-78-3 2,5-Dimethylaniline 

Related news

Structural analysis of liquid 1,4-Dimethylbenzene (cas 106-42-3) at 293 K08/19/2019

Structural analysis of liquid 1,4-dimethylbenzene C6H4(CH3)2 by X-ray monochromatic radiation scattering method was performed. The X-ray measurements were made at room temperature for the scattering angle range Θ varying from 3 to 60°. The most probable parameters of 1,4-dimethylbenzene molecu...detailed

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Boosting the synthesis of value-added aromatics directly from syngasviaa Cr2O3and Ga doped zeolite capsule catalyst

Even though the transformation of syngas into aromatics has been realizedviaa methanol-mediated tandem process, the low product yield is still the bottleneck, limiting the industrial application of this technology. Herein, a tailor-made zeolite capsule catalyst with Ga doping and SiO2coating was combined with the methanol synthesis catalyst Cr2O3to boost the synthesis of value-added aromatics, especiallypara-xylene, from syngas. Multiple characterization studies, control experiments, and density functional theory (DFT) calculation results clarified that Ga doped zeolites with strong CO adsorption capability facilitated the transformation of the reaction intermediate methanol by optimizing the first C-C coupling step under a high-pressure CO atmosphere, thereby driving the reaction forward for aromatics synthesis. This work not only reveals the synergistic catalytic network in the tandem process but also sheds new light on principles for the rational design of a catalyst in terms of oriented conversion of syngas.

Biotransformation of thymol by Aspergillus niger

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Continuous process for the production of aromatic hydrocarbons from n-hexane and C5+ natural gas liquid over Pd-loaded ZSM-5 zeolite

A continuous process for the production of aromatic hydrocarbons from n-hexane and C5+ natural gas liquid (C5+ NGL) over Pd-loaded ZSM-5 zeolite in a tubular reactor was developed. The optimal conditions for continuous aromatization of n-hexane and C5+ NGL were found at 400°C reaction temperature and 0.4 cm3/min reactant feeding rate, employing ZSM-5 (0.5% Pd content) as a catalyst; under these conditions, n-hexane conversion and aromatic contents in reaction product were found to be 99.7% and 92.3%, respectively. GC and GC/MS analysis revealed that this continuous process for n-hexane aromatization yielded both benzene derivatives and naphthalene derivatives, including benzene (5.7%), toluene (23.6%), xylenes (25.0%), 4-ethyltoluene (3.5%), 1,3,5-trimethylbenzene (4.9%), 1-methylnaphthalene (4.3%), and 1,5-dimethylnaphthalene (3.6%). Under the same reaction conditions, C5+ NGL gave 94.3% conversion and 92.6% aromatic contents in reaction product. The composition of product included benzene (8.1%), toluene (23.3%), xylenes (22.8%), 4-ethyltoluene (4.3%), 1,3,5-trimethylbenzene (3.7%), 1-methylnaphthalene (4.1%), and 1,5-dimethylnaphthalene (2.9%).

Guest-selected formation of Pd(II)-linked cages from a prototypical dynamic library [15]

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Pyrolysis of 3-carene: Experiment, Theory and Modeling

Thermal decomposition studies of 3-carene, a bio-fuel, have been carried out behind the reflected shock wave in a single pulse shock tube for temperature ranging from 920 K to 1220 K. The observed products in thermal decomposition of 3-carene are acetylene, allene, butadiene, isoprene, cyclopentadiene, hexatriene, benzene, toluene and p-xylene. The overall rate constant for 3-carene decomposition was found to be k / s-1 = 10(9.95 ± 0.54) exp (- 40.88 ± 2.71 kcal mol-1/RT). Ab-initio theoretical calculations were carried out to find the minimum energy pathway that could explain the formation of the observed products in the thermal decomposition experiments. These calculations were carried out at B3LYP/6-311 + G(d,p) and G3 level of theories. A kinetic mechanism explaining the observed products in the thermal decomposition experiments has been derived. It is concluded that the linear hydrocarbons are the primary products in the pyrolysis of 3-carene.

Renewable p-Xylene from 2,5-Dimethylfuran and Ethylene Using Phosphorus-Containing Zeolite Catalysts

p-Xylene is a major commodity chemical used for the production of polyethylene terephthalate, a polymer with applications in polyester fibers, films, and bottles. The Diels–Alder cycloaddition of 2,5-dimethylfuran and ethylene and the subsequent dehydration of the cycloadduct intermediate is an attractive reaction pathway to produce renewable p-xylene from biomass feedstocks. However, the highest yields reported previously do not exceed 75 %. We report that P-containing zeolite Beta is an active, stable, and selective catalyst for this reaction with an unprecedented p-xylene yield of 97 %. It can catalyze the dehydration reaction selectively from the furan-ethylene cycloadduct to p-xylene without the production of alkylated and oligomerized products. This behavior is distinct from that of Al-containing zeolites and other solid phosphoric acid catalysts and establishes a commercially attractive process for renewable p-xylene production.

Effect of extra-framework Al formed by successive steaming and acid leaching of zeolite MCM-22 on its structure and catalytic performance

Dealuminated MCM-22 samples have been prepared by a two-step dealumination procedure. Detailed assessment of the properties of the materials obtained at each one of the successive stages, i.e. steaming (at 500 °C, 700 °C and 800 °C) and acid reflux (HCl and oxalic), has been made by XRD, N 2 adsorption-desorption, m-xylene adsorption, 27Al MAS NMR and FT-IR of pyridine adsorption. It was found that steaming generates extra-framework aluminum (EFAl) species and the majority of them cannot be extracted by the consecutive acid leaching. These extra-lattice entities block the zeolite micropores which makes the remaining Broensted acid sites isolated and inefficient. It is shown that the presence of such species vastly affects the catalytic performance of zeolite MCM-22 in the reaction of m-xylene conversion. The consequences are reduced adsorption capacity and catalytic activity, modified reaction products distribution, enhanced p-xylene selectivity, as well as altered mode of coke formation and composition of the coke precursors.

Interference by Phosphine Decomposition in Oxidative Additions of Aryl Halides to Methyl-, and Trimethylsilyl-tris(triphenylphosphine)Cobalt

The oxidative addition of aryl halides, ArX, to 3CoCH3 yield ArAr and ArCH3 when Ar= 4-CH3C6H4, but exclusively ArCH3 for 1- and 2-bromo-naphthalene and 4-bromobiphenyl.Decomposition of the phosphine ligand in 3CoCH3 interfers with these reactions to varying extents depending on the relative rates of the reactions; ArCl mostly gives PhPh with some ArPh and ArAr; ArI gives mostly ArAr; ArBr shows intermediate behaviour.Other cobalt compounds such as 3CoSi3, 3CoCH3, 3CoPh and 3CoCH3 and several other organic halides examined show a low activity in the oxidative addition.

A Simple and Mild Approach for the Synthesis of p-Xylene from Bio-Based 2,5-Dimethyfuran by Using Metal Triflates

The production of aromatic platform chemicals from biomass-derived feedstocks is of considerable importance in biomass conversion. However, the development of effective routes with simple steps and under mild conditions is still challenging. In this work, we report an original route for the direct synthesis of p-xylene from 2,5-dimethylfuran and acrylic acid catalyzed by scandium(III) triflate (Sc(OTf)3) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim]NTf2) under mild conditions. An overall 63 % selectivity towards p-xylene and 78 % selectivity towards aromatics were obtained at 90 % conversion of 2,5-dimethylfuran by enhancing the dehydration and introducing an extra one-pot decarboxylation step. Furthermore, various dienes and dienophiles were employed as reactants to extend the substrate scope. The aromatic compounds were obtained in moderate yields, which proved the potential of the method to be a generic approach for the conversion of bio-based furanics into renewable aromatics.

The miracle role of lattice imperfections in benzene alkylation with methanol over mordenite

Mordenite (MOR) has demonstrated potential as a catalyst for alkylation due to high variability, intrinsic porosity, and outstanding stability. However, the contact probability of benzene and methanol has been limited by typical layered structures of MOR and there is no connection between layers. Here, we report the preparedness of H-MOR via a sequential post-treatment method based on a commercial MOR. H-MOR sample had appeared lattice imperfections inferred from characterization means. The samples were tested with benezene methylation reaction. Results show that the high conversion of benzene and the high selectivity of toluene were obtained from the miracle role of lattice imperfections in the H-MOR sample. Sequentially, based on the study of all catalyst structure and physical properties, a plausible reaction mechanism for the selectivity of the desired toluene was proposed.

Preparation of active Cs2HPW12O40 catalyst with the 'core-shell' secondary structure by a self-organizing process

By mixing and ageing of the powdered H3PW12O 40 acid and the Cs3PW12O40 salt, at the molar ratio of 1:2, the Cs2HPW12O40 salt with a unique 'core-shell' secondary structure is being formed. The self-organizing process proceeds in a solid state at ambient temperature and its rate depends on the humidity of air atmosphere. The formation of new secondary structure of the Cs2HPW12O40 salt was proved by number of techniques (XRD, DRIFT, DSC/TG and N2-sorption). Its properties were compared with those of the Cs2HPW12O40 salt prepared by the standard method, with the 'solid solution' secondary structure. The characterization techniques evidenced the substantial differences between various structures of the Cs2HPW12O40 salt. The microcalorimetric method showed that the process of ammonia sorption on the Cs2HPW12O40 salt with the new structure is quite similar to that on the K2HPW12O40 salt with well-known 'core-shell' structure. The catalytic activity of the Cs 2HPW12O40 samples with different secondary structure was compared in the dehydration of ethanol and in the transformation of m-xylene. It turn out that the Cs2HPW12O40 salt with the 'core-shell' structure exhibited significantly higher catalytic activity than the same salt with the 'solid solution' structure and was also more active than the Cs2.5H0.5PW12O 40 salt. It can be suggested that in the 'core-shell' structure of the Cs2HPW12O40 salt the protons are easily accessible for the reactants.

Preparation and characterization of mesoporous Cs2HPW 12O40 salt, active in transformation of m-xylene

The samples of Cs2HPW12O40 salt were precipitated with CsCl, CsBr or CsI reagent as well as with commonly used Cs2CO3. The use of cesium halides resulted in the Cs 2HPW12O40 samples of mesoporous structure composed of relatively loosely aggregated primary particles. It was observed that the type of halogen ion influenced textural properties of the Cs 2HPW12O40 samples. As the atomic size of halogen ion increased (from Cl to I), the specific surface area and microporosity decreased. The so-obtained samples exhibited textural and morphological features similar to those of Cs2.5H 0.5PW12O40 salt. In the transformation of m-xylene, the pore-size sensitive reaction, the catalytic activity of the Cs2HPW12O40 samples prepared with CsBr and CsI reagents was about two-fold higher than that of Cs2.5H 0.5PW12O40 salt. All these samples exhibited similar strength of acid sites. Therefore, high catalytic activity of the samples prepared with CsBr and CsI could be ascribed to their open pore structure, which allowed the accessibility of almost all active sites for m-xylene molecules.

Lewis acid zeolites for tandem Diels-Alder cycloaddition and dehydration of biomass-derived dimethylfuran and ethylene to renewable p-xylene

Lewis acid zeolites including Zr-, Sn-, and Ti-BEA were examined for tandem [4 + 2] Diels-Alder cycloaddition of 2,5-dimethylfuran (DMF) and ethylene to oxanorbornene with subsequent dehydration to produce biorenewable p-xylene. Zr-BEA (Si/Zr = 168) exhibited superior performance with improved recalcitrance to deactivation, which was attributed to its low activity for the hydrolysis of DMF to 2,5-hexanedione and subsequent condensation. Zr-BEA also achieved the highest selectivity to p-xylene of 90% at 99% conversion of DMF. For low catalyst loading within a three-phase reactor, the reaction rate to form p-xylene was linearly proportional to the number of Lewis acid sites, while high catalyst loading exhibited zero order dependence on Lewis acid sites. A maximum achievable reaction rate was shown to be consistent with a transition in rate-limiting reactions from dehydration of oxanorbornene, the Diels-Alder product, to the Diels-Alder cycloaddition of DMF and ethylene.

Atmospheric pressure microwave assisted heterogeneous catalytic reactions

The purpose of the study was to investigate microwave selective heating phenomena and their impact on heterogeneous chemical reactions. We also present a tool which will help microwave chemists to answer to such questions as "My reaction yields 90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes under microwaves?" and to have an approximation of their reactions when conducted under microwaves with different heterogeneous procedures. This model predicting reaction kinetics and yields under microwave heating is based on the Arrhenius equation, in agreement with experimental data and procedures.

Excellent Performances of Dealuminated H-Beta Zeolites from Organotemplate-Free Synthesis in Conversion of Biomass-derived 2,5-Dimethylfuran to Renewable p-Xylene

Direct synthesis of renewable p-xylene (PX) by cycloaddition of biomass-derived 2,5-dimethylfuran (2,5-DMF) and ethylene was achieved over Al-rich H-beta zeolites synthesized by an organotemplate-free approach and their dealuminated counterparts with different Si/Al ratios. Among them, H-beta zeolite with an Si/Al ratio of 22, obtained from an Al-rich parent by dealumination, was found to be an excellent catalyst for the synthesis of PX. A PX yield of 97 % and 2,5-DMF conversion of 99 % were obtained under optimized conditions. These results are even better than those of a commercial H-beta zeolite prepared using a organotemplate synthesis with a similar Si/Al ratio of 19. The excellent performance of the H-beta zeolite with Si/Al ratio of 22 is closely related to its acidity and porous structure. A moderate Br?nsted/Lewis acid ratio can improve the conversion of 2,5-DMF to as high as 99 %. Furthermore, dealuminated H-beta zeolite has a secondary pore system that facilitates product diffusion, which increases the selectivity to PX. In addition, this catalyst shows better regeneration. After five successive regeneration cycles, the yield of PX was still as high as 85 % without obvious dealumination. This work provides a deeper understanding of the more general Diels–Alder cycloaddition of furan-based feedstocks and olefins and significantly improves the potential for the synthesis of chemicals from lignocellulosic biomass.

Regeneration of Pentasil Zeolite Catalysts using Ozone and Oxygen

A novel procedure for the removal of carbonaceous deposits from zeolites using ozone-enriched oxygen is described.Pentasil zeolites (SiO2/Al2O3 mole ratios 35, 70) were studied and deactivated using methanol conversion to hydrocarbons and o-xylene isomerisation.Low temperature ozone reactivation was found to restore the catalyst activity for these reactions and hence can be considered as an alternative procedure to high temperature oxygen reactivation currently utilised industrially.Ozone reactivation was found to increase slightly the catalyst lifetime and also to reduce the initial methane yield when compared with oxygen reactivation.

Kinetic Study of Carbonylation of α-Bromo-p-xylene with Iron Pentacarbonyl by Phase-Transfer Catalysis

The reaction kinetics of the carbonylation of α-bromo-p-xylene (BrCH2C6H4CH3, BX) with iron pentacarbonyl (Fe(CO)5) by phase-transfer catalysis was studied in an organic solvent/alkaline solution. The concentration of tetra-n-butylammonium bromide ((n-C4H9)4NBr, TBAB), NaOH, NaBr, aqueous volume and temperature were evaluated to achieve the optimum reaction condition. The reaction behavior was discussed by the apparent reaction-rate constants for BX and bis(p-methylbenzyl) ketone ((p-CH3C6H4CH2)2CO, BMBK), respectively, and the relationship of consumption of BX and Fe(CO)5. The product distributions of BX with Fe(CO)5 on various reactions conditions were measured. The activation energies was obtained at TBAB = 1.24 and 0 mmol as Well.

Synthesis of HZSM-5@silicalite-1 core-shell composite and its catalytic application in the generation of p-xylene by methylation of toluene with methyl bromide

A core-shell HZSM-5@silicalite-1 composite was synthesized by overgrowing silicalite-1 on the external surface of HZSM-5, and was characterized by XRD, SEM, TEM, NH3-TPD, 1,3,5-triisopropylbenzene (TIPB) cracking and N2 adsorption-desorption techniques. When used as a catalyst for the formation of p-xylene through toluene methylation with methyl bromide, the HZSM-5@silicalite-1 composite exhibits para-selectivity of up to 76% with no evidence of deactivation in an on stream period of 3 h. The excellent catalytic performance is attributed to the inactive silicalite-1 shell that extends the diffusion path length of xylenes while having the acid sites on the external surface of HZSM-5 fully covered. the Partner Organisations 2014.

Route to Renewable PET: Reaction Pathways and Energetics of Diels-Alder and Dehydrative Aromatization Reactions between Ethylene and Biomass-Derived Furans Catalyzed by Lewis Acid Molecular Sieves

Silica molecular sieves that have the zeolite beta topology and contain framework Lewis acid centers (e.g., Zr-β, Sn-β) are useful catalysts in the Diels-Alder and dehydrative aromatization reactions between ethylene and various renewable furans for the production of biobased terephthalic acid precursors. Here, the main side products in the synthesis of methyl 4-(methoxymethyl)benzene carboxylate that are obtained by reacting ethylene with methyl 5-(methoxymethyl)-furan-2-carboxylate are identified, and an overall reaction pathway is proposed. Madon-Boudart experiments using Zr-β samples of varying Si/Zr ratios clearly indicate that there are no transport limitations to the rate of reaction for the synthesis of p-xylene from 2,5-dimethylfuran and ethylene and strongly suggest no mass transport limitations in the synthesis of methyl p-toluate from methyl 5-methyl-2-furoate and ethylene. Measured apparent activation energies for these reaction-limited systems are small (13C kinetic isotope effects (KIE) in the synthesis of MMBC and MPT measured by gas chromatography/isotope-ratio mass spectrometry in reactant-depletion experiments support the Madon-Boudart result that these systems are not transport-limited and the KIE values agree with those previously reported for Diels-Alder cycloadditions.

Quantification of Bronsted acid sites of grafted amorphous silica-alumina compounds and their turnover frequency in m-xylene isomerization

The number and types of acid sites and the catalytic activity of amorphous silica-alumina, obtained by grafting silicon species to the surface of γ-alumina, varies with the synthesis conditions and the amount of grafted silicon. IR spectroscopy of the OH region proves that deposition occurs selectively, first on the (1 0 0) and then on the (1 1 0) facets. Grafting onto the (1 0 0) surface lowers the number of active sites in ethanol dehydration. Grafting onto the (1 1 0) surface yields Bronsted acid sites that are active in the dehydration of ethanol and that catalyze the isomerization of m-xylene. Strong Lewis acid sites, or "defect sites", as detected by CO adsorption, also appear, although they are absent on the parent alumina. The stoichiometric dehydration of ethanol on Bronsted sites, monitored by using thermogravimetric analysis, enables the calculation of the turnover frequency of these sites in m-xylene isomerization (1.410-3 s -1 site-1 at 350 °C, atmospheric pressure, 0.6 cm 3 h-1 of m-xylene, and 0.5 g of catalyst). This number is 22 times lower than on a USY zeolite without extraframework aluminum. Multifaceted γ-alumina: Under mild conditions, tetraethyl orthosilicate (TEOS) is first deposited on the (1 0 0) surface of γ-alumina, and then on the (1 1 0) surface. The latter step enables the formation of Bronsted acid sites upon calcination, which are less active than those present in an H-USY zeolite. Copyright

Preparation of an MCM-22/Hydrotalcite Framework Composite and Its Catalytic Application

A composite material (MAMCM), possessing both a layered cationic MgAl-hydrotalcite (MA-HT) and an anionic MCM-22 framework, was prepared by a simple coprecipitation method. The resulting composite material has features of both MCM-22 and the HT layered framework, as shown by powder XRD, FTIR, 29Si and 27Al-MAS NMR spectroscopy, and SEM studies. Electron microscopy revealed that the layer sheets are arranged in a spherical morphology. The composite material was utilized for the vapor-phase alkylation of toluene. The MAMCM material showed better toluene conversion than MCM-22 and MA-HT materials.

ORBITAL-CONTROLLED REACTIONS CATALYSED BY ZEOLITES: ELECTROPHILIC ALKYLATION OF AROMATICS

The role of orbital control in product selectrivity during electrophilic alkylation catalysed by zeolites was studied both theoretically and experimentally.In order to discuss this, the alkylation of toluene and m-xylene by methanol was carried out on a series of large-pore zeolites (HY).The changes in the para to ortho ratio observed on changing the framework Si/Al ratio of the zeolites were related to ab initio molecular orbital calculations of the LUMO energy of structurally alike model clusters but containing different tetrahedral cations around the active site.The observed correlation is discussed in terms of the HSAB principle by taking into account the influence of the catalyst composition on the reactivity of the electrophilic reagent.

Transformation of aromatic hydrocarbons over isomorphously substituted UTL: Comparison with large and medium pore zeolites

Isomorphously substituted UTL zeolite with heteroatoms Al, Ga and Fe was synthesized, characterized by X-ray powder diffraction, scanning electron images, nitrogen adsorption isotherms and pyridine adsorption followed by FTIR spectroscopy and tested in disproportionation of toluene, toluene alkylation with isopropyl alcohol and trimethylbenzene disproportionation/isomerization. The catalytic properties of UTL zeolites were compared with those of BEA and MFI zeolites and the observed differences are discussed. Isomorphously substituted (Al, Ga, Fe) UTL zeolites show in most cases lower conversions for the reactions studied but higher selectivities to more valuable products. For toluene disproportionation reaction UTL zeolites shown higher selectivity to xylenes compared with BEA and MFI. In toluene alkylation with isopropyl alcohol no n-propyltoluenes are formed(Ga)UTL or (Fe)UTL while some traces of this undesired product were observed(Al)UTL. (Al)UTL shows high selectivity to cymenes and iso-/n-propyltoluene ratio orders of magnitude higher than for MFI. The initial selectivity to xylenes in trimethylbenzene disproportionation/ isomerization decreases in the order (Ga)UTL > (Al)UTL ≈ BEA > MFI and correlates with increasing of acid centres strength, showing that isomorphously substituted extra-large pore zeolites can be enough active and more selective catalysts in some aromatic hydrocarbon transformation reaction.

Rational Design of Zinc/Zeolite Catalyst: Selective Formation of p-Xylene from Methanol to Aromatics Reaction

The production of p-xylene from the methanol to aromatics (MTA) reaction is challenging. The catalytic stability, which is inversely proportional to the particle size of the zeolite, is not always compatible with p-xylene selectivity, which is inversely proportional to the external acid sites. In this study, based on a nano-sized zeolite, we designed hollow triple-shelled Zn/MFI single crystals using the ultra-dilute liquid-phase growth technique. The obtained composites possessed one ZSM-5 layer (≈30 nm) in the middle and two silicalite-1 layers (≈20 nm) epitaxially grown on two sides of ZSM-5, which exhibited a considerably long lifetime (100 % methanol conversion >40 h) as well as an enhanced shape selectivity of p-xylene (>35 %) with a p-xylene/xylene ratio of ≈90 %. Importantly, using this sandwich-like zeolite structure, we directly imaged the Zn species in the micropores of only the ZSM-5 layer and further determined the specific structure and anchor location of the Zn species.

Comparison of Physicochemical Properties and Catalytic Activity in the m-Xylene Isomerization of Catalysts Based on ZSM-12 Zeolites Prepared at Hydrothermal Conditions and under the Action of Microwave Radiation

The properties of ZSM-12 zeolites prepared under hydrothermal conditions and microwave radiation influence were investigated. The prepared zeolites were characterized by various physicochemical methods of analysis, e.g., X-ray diffraction analysis, low-temperature nitrogen adsorption/desorption, scanning electron microscopy, solid-state 27Al and 29Si NMR spectroscopy, IR spectroscopy, temperature-programmed desorption of ammonia, IR spectroscopy of adsorbed pyridine, and X-ray fluorescence elemental analysis. The calcined zeolites were impregnated with 0.5 wt.% Pt, which performed the hydrogenation function in the reaction under study. The obtained materials were evaluated in the m-xylene isomerization reaction under the following conditions: Т = 300°С–440°С, WHSV = 1/hr, Р(Н2) = 10 atm. On the ZSM-12 MW catalyst, due to its high acidity and fine particles, which promoted high mass transfer, it is possible to increase the yields of m-xylene isomers, in particular p-xylene, to 36%–65%.

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions

Upgrading biomass-derived phenolic compounds provides a valuable approach for the production of higher-value-added fuels and chemicals. However, most established catalytic systems display low hydrodeoxygenation (HDO) activities even under harsh reaction conditions. Here, we found that Pd supported on –NH2-modified hierarchically porous carbon (Pd/HPC–NH2) with formic acid (FA) as hydrogen source exhibits unprecedented performance for the selective HDO of benzylic ketones from crude lignin-derived oxygenates. Designed experiments and theoretical calculations reveal that the H+/H? species generated from FA decomposition accelerates nucleophilic attack on carbonyl carbon in benzylic ketones and the formate species formed via the esterification of intermediate alcohol with FA expedites the cleavage of C–O bonds, achieving a TOF of 152.5 h?1 at 30°C for vanillin upgrading, 15 times higher than that in traditional HDO processes (～10 h?1, 100°C–300°C). This work provides an intriguing green route to produce transportation fuels or valuable chemicals from only biomass under mild conditions.