Cumene, as solvent

Treating 2-bromothiazole with copper at 170°C in cumene as solvent affords the 2.2 -bisthiazole (Scheme 9) (69). The 2-halogenothiazoles can... 

Deoxygenation of l,2-dimethyl-3-(o-nitrophenylthio)indole (133) with an excess of triethyl phosphite, either neat or with cumene as solvent, at 160°C afforded indolo[2,3-c][l,5]benzothiazepine (134) in 34% yield. This product may arise via //wo-substitution by the initially formed nitrene to the 3-position of the indole nucleus to give the intermediate 135 (Scheme 41) [88JCR(S)272]. 

For reactive stripping experiments, ca. 13 L of liquid was used containing cumene as solvent, tetradecane as internal standard, and ca. 12 mol% each of hexanoic acid and octanol-1. For the experiments with elevated acid concentrations, these values were 20 mol% and 11 mol%, respectively. All experiments were carried out at 160 °C and 5 bar absolute pressure. 

Major markets as solvents and intermediates have made the ketones important commercial products lor many years. Acetone and mcthylethyl ketone have had the most impact on the chemical industry Acetone Is used s an intermediate In methyl isobutyl ketone, methyl methacrylate, diucelonc alcohol. ketone. hisphenol-A. phiwnc. and mesityl oxide Acetone is largely produced by dehydration of isopropyl alcohol In the production of phenol from cumene, acetone is produced as a by-product This mute to acetone has tended to control its price. 

Production of monochlorobenzenes peaked in the 1960s with production volume at about 600 million lb. It was down to 152 million lb in 1998. The most significant cause for the decline is the replacement of monochlorobenzene by cumene as the preferred raw material for phenol manufacture. Other reasons include the elimination of the herbicide DDT, the change of diphenyl oxide process from chlorobenzene to phenol and a significant drop in solvent use. The production volume for ODCB and PDCB were 50 and 91 million lb, respectively, in 1998. 

Photocleavage of phenacyl derivatives was first reported by Sheehan and Umezawa in 1973.40 In contrast to the 2-nitrobenzyl protecting groups, choice of solvent is important because the solvent acts as a hydrogen donor. The cleavage takes place by a radical mechanism as shown in Scheme L21. Typical solvents include ethanol dioxane and benzene containing cumene as hydrogen donor. 

Catalytic oxidation of cyclohexene with cumene hydroperoxide gave 2 cyclohexen-l-ol and 2-cyclohexenone. Cydohexene oxide was not formed under the reaction conditions. The effect of various solvents on the oxidation reactions was smdied. The reaction was performed in polar, nonpolar, protic and aprotic solvents. Si ificant variation in product yield was observed. Table-1 shows the distribution of product yield with different solvents. Maximum conversion was observed in chloroform. The eflSciency of the catalyst for 2-cyclohexen-l-ol formation in chloroform is of the order, catalyst (2) > (3) > (1). When methanol was used as solvent the selectivity fijr epoxide was highest with catalyst (3), In this complex the selectivity fiar the formation of the allylic oxidation products are comparatively low. With catalyst (l),m methanol as solvent, 2-cyclohexen-l-ol was obtained in higher yield than eporade. With catalyst (1) the yield of the product was maximum when benzene was used as the solvent. Percentage conversion was the highest (39%). 

AI3-03976 Asymmetrical trimethylbenzene Benzene, 1,2,4-trimethyl- Benzene, 1,2,5-trimethyl- EINECS 202-436-9 HSDB 5293 NSC 65600 Pseudocumene Pseudocumol psi-Cumene as-Trimelhylbenzene Uns-trimethylbenzene. Used as a solvent in chemical manufacturing and in scintillation counters. Oil mp = -43.8° bp = 169.3° d O = 0.8578 Xm = 267, 277 nm (MeOH) insoluble in H2O, freely soluble in EtOH, EtzO, MezCO, CsHe, CCI4, petroleum ether. 

Small amounts of cumene are used as thinners for paints, lacquers, and enamels, and as solvents in paints and other types of coatings. By far the greatest amount of cumene, however, is used as a raw material in the manufacture of phenol, acetone, and methyl styrene. These compounds, in turn, have a great many chemical and industrial uses. Some of the most important uses are the production of plastics, such as polystyrene, phenol-formaldehyde resins, and polycarbonates. 

These reactions are of interest because of their involvement in a scheme proposed for separation of mixtures of o- and p-cresols. Consider these reactions as they occur in the liquid phase at 60° C with cumene as the solvent in the presence of an Amberlyst 15 catalyst. For this system at this temperature, the ratio of rate constants (k /IC2) is 4.8. 

Gumylphenol. -Cumylphenol (PGP) or 4-(1-methyl-l-phenylethyl)phenol is produced by the alkylation of phenol with a-methylstyrene under acid catalysis. a-Methylstyrene is a by-product from the production of phenol via the cumene oxidation process. The principal by-products from the production of 4-cumylphenol result from the dimerization and intramolecular alkylation of a-methylstyrene to yield substituted indanes. 4-Cumylphenol [599-64-4] is purified by either fractional distillation or crystallization from a suitable solvent. Purification by crystallization results in the easy separation of the substituted indanes from the product and yields a soHd material which is packaged in plastic or paper bags (20 kg net weight). Purification of 4-cumylphenol by fractional distillation yields a product which is almost totally free of any dicumylphenol. The molten product resulting from purification by distillation can be flaked to yield a soHd form however, the soHd form of 4-cumylphenol sinters severely over time. PGP is best stored and transported as a molten material. 

The acetone supply is strongly influenced by the production of phenol, and so the small difference between total demand and the acetone suppHed by the cumene oxidation process is made up from other sources. The largest use for acetone is in solvents although increasing amounts ate used to make bisphenol A [80-05-7] and methyl methacrylate [80-62-6]. a-Methylstyrene [98-83-9] is produced in controlled quantities from the cleavage of cumene hydroperoxide, or it can be made directly by the dehydrogenation of cumene. About 2% of the cumene produced in 1987 went to a-methylstyrene manufacture for use in poly (a-methylstyrene) and as an ingredient that imparts heat-resistant quaUties to polystyrene plastics. 

Cumene in minor amounts is used as a thinner for paints, enamels, and lacquers and to produce acetophenone, the chemical intermediate dicumylperoxide, and diisoprop5lben2ene. It is also a good solvent for fats and resins and, as such, has been suggested as a replacement for ben2ene in many of its industrial appHcations (22). 

Cumene (isopropylhenzene), a liquid, is soluble in many organic solvents hut not in water. It is present in low concentrations in light refinery streams (such as reformates) and coal liquids. It may he obtained by distilling (cumene s B.P. is 152.7°C) these fractions. 

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