Toluene-4-sulfonic acid methyl ester

A mixture of 11.8 g of (+/-)-3a,6,7,7a-tetrahydro-4-methyl-2-oxo-ip-indaheptanoic acid methyl ester, 27 ml of ethylene glycol and 300 mg of p-toluene sulfonic acid mono-hydrate in 600 ml of benzene was refluxed with stirring for 18 hours using a Dean-Stark trap to separate the water formed in the reaction. The reaction mixture was cooled and added to 300 ml of cold 5% potassium bicarbonate. The aqueous layer extracted twice with 2 1 benzene-hexene. The combined organic fractions were washed 3 times with saturated aqueous NaCI, dried over sodium sulfate and evaporated to dryness... 

The analysis of surface-active anions comprises the determination of simple aromatic sulfonic acids, hydrotropes (toluene, cumene, and xylene sulfonates), alkane- and alkene sulfonates, fatty alcohol ether sulfates, alkylbenzene sulfonates, and a-sulfofatty acid methyl esters. Many of these compounds are relevant predominantly in the detergent and cleansing industry. 

Methyl ester, Cl9Hw02f methyl oleate. Prepd by refluxing oleic acid with p-toluene sulfonic acid in methanol Rubin,... 

Recently, several other aminopolymers were synthesized for the NCA polymerization. Ichie and coworkers used copolymers of styrene-vinyl benzylamine and methyl methacrylate-vinyl benzylamine for NCA polymerization to study the kinetics of NCA polymerization with macroinitiators. 2 The polymerization was Ist-order with respect to monomer concentration and was much faster in nitrobenzene than in dioxane or THF. Kiba patented a new system for NCA polymerization with the different aminopolymers [38] produced according to Scheme 5. He also claimed the ester exchange reaction of the resulting graft copolymer with ethylene cyanohydrin over p-toluene sulfonic acid. 

Benzenesulfnmc acid, 4-methyl-, cyclopentyl ester [Cyclopentanol, p-toluene-sulfonate], 55, 112... 

One Sanofi synthesis of enantiomerically pure (-i-)-clopidogrel (2) utilized optically pure (R)-(2-chloro-phenyl)-hydroxy-acetic acid (20), a mandelic acid derivative, available from a chiral pool. After formation of methyl ester 21, tosylation of (/ )-21 using toluene sulfonyl chloride led to a-tolenesulfonate ester 22. Subsequently, the Sn2 displacement of 22 with thieno[3,2-c]pyridine (8) then constructed (-i-)-clopidogrel (2). Another Sanofi synthesis of enantiomerically pure (-i-)-clopidogrel (2) took advantage of resolution of racemic a-amino acid 23 to access (S)-23. The methyl ester 24 was prepared by treatment of (S)-23 with thionyl chloride and methanol. Subsequent Sn2 displacement of (2-thienyl)-ethyl para-toluene-sulfonate (25) assembled amine 26. 

Preparation of toluene-4-sulfonic acid 7,8-dihydro-6H-5-oxa-l-aza-phenanthren-6-yl-methyl ester... 

Solid esters are easily crystallisable materials. It is important to note that esters of alcohols must be recrystallised either from non-hydroxylic solvents (e.g. toluene) or from the alcohol from which the ester is derived. Thus methyl esters should be crystallised from methanol or methanol/toluene, but not from ethanol, n-butanol or other alcohols, in order to avoid alcohol exchange and contamination of the ester with a second ester. Useful solvents for crystallisation are the corresponding alcohols or aqueous alcohols, toluene, toluene/petroleum ether, and chloroform (ethanol-free)/toluene. Esters of carboxylic acids derived from phenols are more difficult to hydrolyse and exchange, hence any alcoholic solvent can be used freely. Sulfonic acid esters of phenols are even more resistant to hydrolysis they can safely be crystallised not only from the above solvents but also from acetic acid, aqueous acetic acid or boiling n-butanol. Note that sulfonic esters of lower alcohols, e.g. methanol, are good alkylating agents. 

Methyl />-toluenesulfonate may be prepared in a somewhat similar manner with good yields. One kilo of methyl alcohol (90-95 per cent) is placed in a round-bottom flask, placed in an ice-salt bath. One kilo of powdered pure p-toluencsulfo-chloride (crude material may be used but the yield of product drops to about 75 per cent) is added with mechanical stirring. Prom a separatory funnel 840 g. of 25 per cent sodium hydroxide solution is added drop by drop. The temperature must be held at about 23-27° for the best results. When all this alkaline solution is added the reaction mixture is tested with litmus if not alkaline, more alkali is added until the neutral point is reached. Upon standing several hours the ester sinks and the alcohol forms the top layer. The alcohol may be siphoned off and used in subsequent experiments, the methyl /(-toluene-sulfonate is washed with water to remove a little salt and then with 5 per cent hydrochloric acid to dissolve the iron. Finally it is... 

Silver-ion chromatography can be a useful technique for isolation of a fraction enriched in CLA, but it can also afford unrivaled analytical separations. Silver-ion thin-layer chromatography (TLC) is best regarded as an enrichment method. With a mobile phase such as hexane/diethyl ether (9 1, vol/vol), CLA as the methyl ester elutes with cis-monoenes, rather than with a diene fraction with toluene as mobile phase, it elutes just ahead of the cw-monoenes (10). Alternatively, solid-phase extraction columns with bonded sulfonic acid moieties converted to the silver-ion form can be used with a simple elution scheme to obtain a combined monoene-CLA fraction (2,11). 

Synthesis of Esters and Aldehydes. Monoalkylation of methylthiomethyl p-tolyl sulfone (MT-sulfone) with an alkyl halide is achieved by the action of a phase-transfer catalyst (PTC) in toluene-50% aq NaOH. sodium hydride and butyl-lithium also generate a carbanion of MT-sulfone. Arylmethyl derivatives of MT-sulfone are prepared by sodium borohydride reduction of the Knoevenagel condensation products with aromatic aldehydes. The monoalkylated products are converted into the corresponding methyl esters (eq 1). This functionalization can be utilized for synthesizing a-alkoxy carboxylic esters (eq 2) and Q -amino acids (eq 3). ... 

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