P-Toluenesulphonates

The sulphuric acid may be replaced by 1-2 g. of sulphamic acid (NH,SOjH) or by p-toluenesulphonic acid (p-CHjCjH SOjH). 

By the interaction of a Grignard reagent and an alkyl p-toluenesulphonate for example ... 

Prepare a solution of benzyl magnesium chloride in a 2-litre three-necked flask from 24-3 g. of magnesium turnings, 600 ml. of sodium-dried ether and 126-5 g. (115 ml.) of redistilled benzyl chloride follow the experimental details given under n-Propylbenzene (Section IV,7). Cool the flask in running water or in ice water. Place a solution of 456 g. of n-butyl-p-toluenesulphonate (Section IV,198) in about twice its volume of anhydrous ether in the dropping funnel, and add it slowly with stirring, at such a rate that the ether just boils a white solid soon forms. The addition is complete after about 2 hours. Pour the reaction product... 

The melting points of a number of sulphonacetamides are —benzene-sulphonic acid, 125° p-toluenesulphonic acid, 137° p-bromobenzene-sulphonic acid, 203° m-nitrobenzenesulphonic acid, 189° p-nitroben-zenesulphonic acid, 192° naphthalene-a-sulphonic acid, 185° and naphthalene-p-sulphonic acid, 146°. 

Metho-p-toluenesulphonate. Methyl p-toluenesulphonate combines with many tertiary amines to yield crystalline deiivates ... 

The benzyl chloride quaternary salts RR R"NC3HsCH2 +Cl are prepared similarly 3 g. of redistilled benzyl chloride replaces the methyl p-toluenesulphonate. 

Method 2. The procedure described under Benzenesulphonyl Chloride, Method 2 (Section IV,206) may be used with suitable adjustment for the difierence in molecular weights between sodium p-toluenesulphonate (Section IV,30) and sodium benzenesulphonate. When the reaction product is poured on to ice, the p-toluenesulphonyl chloride separates as a sohd. This is filtered with suction it may be recrystaUised from hght petroleum (b.p. 40-60°) and then melts at 69°. 

Methyl p-toluenesulphonate. This, and other alkyl esters, may be prepared in a somewhat similar manner to the n-butyl ester with good results. Use 500 g. (632 ml.) of methyl alcohol contained in a 1 litre three-necked or bolt-head flask. Add 500 g. of powdered pure p-toluene-sulphonyl chloride with mechanical stirring. Add from a separatory funnel 420 g. of 25 per cent, sodium hydroxide solution drop by drop maintain the temperature of the mixture at 23-27°. When all the alkali has been introduced, test the mixture with litmus if it is not alkaline, add more alkali until the mixture is neutral. Allow to stand for several hours the lower layer is the eater and the upper one consists of alcohol. Separate the ester, wash it with water, then with 4 per cent, sodium carbonate solution and finally with water. Dry over a little anhydrous magnesium sulphate, and distil under reduced pressure. Collect the methyl p-toluenesulphonate at 161°/10 mm. this solidifies on cooling and melts at 28°. The yield is 440 g. 

The alkyl esters of sulphonlc acids exhibit properties similar to those of the alkyl sulphates, and are hydrolysed, by boiling with aqueous alkalis, to the alcohols and sulphonates. Thus with ethyl p-toluenesulphonate ... 

Supplement (combined with Volume XII) XI, 2nd 1933 1605-1739 2. Sulphonic acids Benzenesulphonic acid, 26. p-Toluenesulphonic acid, 97. Naphthalene - sulphonic acid, 155. Hydroxy-Sulphonic acids Phenol-sulphonic acid, 234. Naphthol-sulphonic... 

The A-methyl bases may be reached more directly by converting 2 6-di-(6-phenylacetylenylpyridine (XI) metho-p-toluenesulphonate, by treatment with slightly diluted sulphuric acid at 125°, into 2 6-diphenacylpyridine (XII) metho-p-toluenesulphonate. This, on direct hydrogenation, gives, with 3 mols. of hydrogen, lobelanine (VIII), or, with 5 mols. of hydrogen, lobelanidine (XIII NH— NMe). 

The striking effect of the catalyst is exemplified by the reaction of pregna-4, 16-diene-3,20-dione (10) with benzyl mercaptan. In the presence of piperidine only conjugate addition occurs to give (11) whereas with pyridine hydrochloride only the 3-benzyl thioenol ether (12) is formed. In the presence of p-toluenesulphonic acid both reactions take place to yield (13). 

Further mechanistic evidence was provided by Benkeser and Krysiak658, who determined the effects of added salts and water on the rates of cleavage of xylyltrimethylsilanes by p-toluenesulphonic acid in acetic acid at 25 °C, the progress of the reaction being followed by dilatometry the first-order rate coefficients are given in Table 227. Clearly the addition of water retards the reaction, as... 

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