Cyclohexane carboxylic add

Figure 2.11 shows schematically the individual processes for the synthesis of caprolactam. The solid lines indicate processes that have been practiced commercially. As can be seen, all processes start from materials that belong to the group consisting of phenol, benzene, toluene, and cyclohexane. The chemistry of different processes has been reviewed [27,90,91]. Commercially, processes 1, 2, and 3 as shown in Figure 2.11 are important. The principal intermediates are cyclohexanone and cyclohexanone oxime for process 1, cyclohexanone oxime for process 2 [92-95], and cyclohexane carboxylic add for process 3. 

NAPHTHENIC ACIDS. The term naphthenic acid, as commonly used in the petroleum industry, refers collectively to all of the carboxylic adds present m crude oil. Naphthenic adds are classified as monobasic carboxylic acids of the general formula RCOOH, where R represents the naphthene moiety consisting of cyclopentine and cyclohexane derivatives. Naphthenic adds are composed predominantly of alkyl-substituted cycloaliphatic carboxylic adds, with smaller amounts of acyclic aliphatic (paraffinic or fatty) acids. Aromatic, okfinic. hydroxy, and dibasic acids are considered to be minor components. Commercial naphthenic aads also contain varying amounts of unsaponifiable hydrocarbons, phenolic compounds, sulfur compounds, and water. The complex mixture of adds is derived from straight-run distillates of petroleum, mostly from kerosene and diesel fractions. See also Petroleum. 

As discussed elsewhere in this review, Lewis bases such as tetrahydrofuran are known to promote disaggregation of polymeric organolithium speciesThus, in the presence of excess tetrahydrofuran, both poly(styryl)lithium and poly(isopre-nyl)lithium would be expected to be unassociated (or at least much less associated). Therefore, in the presence of sufficient tetrahydrofuran, the carbonation reaction would take place with unassociated organolithium chain ends and ketone formation (Eq. (73)) would only be an intermolecular reaction (rather than an essentially intramolecular reaction as in the case with the aggregated species) competing with carbonation. In complete accord with these predictions, it was found that the carbonation of poly(styryl)lithium, poly(isoprenyl)lithium, and poly(styrene-h-isoprenyl)lithium in a 75/25 mixture (by volume) of benzene and tetrahydrofuran occurs quantitatively to produce the corresponding carboxylic add chain ends. The observation by Mansson that THF has no apparent influence was complicated by the use of methyl-cyclohexane, which is a Theta solvent for poly(styrene) (60-70 °C) furthermore. 

The main field of application for benzoic acid is the production of phenol however, the significance of this phenol route has declined in recent years. Additionally, benzoic acid is used in the production of benzoyl chloride and sodium benzoate. In Italy, benzoic acid is used as the raw material for the production of 8-caprolactam, in a process developed by Snia Viscosa, This involves hydrogenating benzoic add at 170 °C and 15 bar over a palladium catalyst, purifying the cyclohexane carboxylic acid by distillation followed by its reaction with nitrosyl-sulfuric acid to yield 8-caprolactam. 

DNP dinitrophenyl CBZ carbobenzoxy OBzt benzylesters bNA naphthyl amide TCP tetrachlorofluorescein amaryllis alkaloids crinine, powelline, and crinamidine vinca alkaloids vincamine and vindne structural isomers 2- and 6-nitro-3-acetamido-4-chlorobenzoic acid stereoisomers 4-methoxymethyl-1-methyl-cyclohexane carboxylic acid fish oil mixture of docosahexaenoic acid and eicosapentaenoic acid NDGA nordihydroguaiaretic add. 

The transformation of aldehydes to carboxylic acids is a fundamental reaction in organic synthesis. Many successful methods have been developed for these types of oxidations [1], but most of them have limitations as they require stoichiometric amounts of oxidants such as chlorite [2], diromium(VI) reagents [3], potassium permanganate [4], or peroxides [5]. The use of organic solvents e.g., acetonitrile, didiloromethane, cyclohexane, formic add, or benzene is also usually necessary. Despite the fact that these methods have several disadvantages, such as low selectivity and production of waste, some of them have been widely used in industry and are still in use today. The growing awareness of the environment has created a demand for efficient oxidation processes with environmentally friendly oxidants under mild conditions ( green chemistry) [6]. 

This procedure illustrates a general method of carboxylating saturated hydrocarbons that have a tertiary hydrogen.7 It has been used to convert isopentane to 2,2-dimethylbutanoic acid, 2,3-dimethylbutane to 2,2,3-trimethylbutanoic acid, and methyl-cyclohexane to 1-methylcydohexanecarboxylic add. 

Dissolve, in a hydrogenator, 14 kg of benzyl ester of the (2S,3aS,7aS)-l- 2-[l-(ethoxycarbonyl)-(S)-butylamino]-(S)-propionyl octahydroindole-2-carboxylic acid in cyclohexane. Add the charcoal containing 5% palladium and approximately 50 liters of water. Hydrogenate at ordinary temperature and pressure until the theoretical volume of hydrogen has been absorbed. Filter, wash the insoluble material with cyclohexane, separate off the organic phase and wash the aqueous phase again with cyclohexane. Isolate the (2S,3aS,7aS)-l- 2-[l-(ethoxycarbonyl)-(S)-butylamino]-(S)-propionyl octahydroindole-2-carboxylic acid from the aqueous phase by freeze-drying. 

Nitrocyclohexane has been prepared by E. I. du Pont de Nemours Company by nitration of cyclohexane. Cyclohexane undergoes nitration and oxidation to give nitrocyclohexane and adipic acid along with smaller amounts of glutaric acid and succinic add. Nitration is accelerated by the addition of nitrogen dioxide. The process may be operated continuously in the liquid phase with 45-75 per cent nitric acid at temperatures of 100-200 C and pressures of 2-10 atm. This process is of particular interest in that oxidation products from cycloalkanes are usually S3rmmetrical di-carboxylic acids, which are of industrial importance. 

The most common accelerators for methyl ethyl ketone peroxide and cyclohexanone peroxide are salts of metals which exhibit more than one valency. The most widely used metal of this kind is cobalt, although salts of cerium, iron, manganese, tin and vanadium also find some application. In order to be effective as an accelerator a metal salt must be soluble in the polyester resin. The most commonly used salts are naphthenates, which are readily soluble octoates also may be used. (Naphthenic add is extracted from the gas oil and kerosene fractions of petroleum and consists of a complex mixture of carboxylic acids of substituted cyclopentanes and cyclohexanes. ) The decomposition of a hydroperoxide (ROOH) by a metal salt such as cobalt naphthenate to give free radicals proceeds according to the following chain reaction ... 

---