P-Toluenesulphonyl chloride

Dissolve 0 01 g. equivalent of the amino acid in 20 ml. of N sodium hydroxide solution and add a solution of 2 g. of p-toluenesulphonyl chloride in 25 ml. of ether shake the mixture mechanically or stir vigorously for 3-4 hours. Separate the ether layer acidify the... 

Method 1. Treat 2 0 g. of the mixture of amines with 40 ml. of 10 per cent, sodium hydroxide solution and add 4 g. (3 ml.) of benzenesulphonyl chloi de (or 4 g. of p-toluenesulphonyl chloride) in small portions. Warm on a water bath to complete the reaction. Acidify the alkaline solution with dilute hydrochloric acid when the sulphonamides of the primary and secondary amines are precipitated. Filter off the solid and wash it with a little cold water the tertiary amine will be present in the filtrate. To convert any disulphOnamide that may have been formed from the primary amine into the sulphonamide, boil the solid under reflux with 2 0 g. of sodium dissolved in 40 ml. of absolute ethyl alcohol for 30 minutes. Dilute with a little water and distil off the alcohol filter off the precipitate of the sulphonamide of the secondary amine. Acidify the filtrate with dilute hydrochloric acid to precipitate the derivative of the primary amine. Recrystallise the respective derivatives from alcohol or from dilute alcohol, and identify them inter alia by a determination of the m.p. 

Method 2. Place a 3 0 g. sample of the mixture of amines in a flask, add 6g. (4-5 ml.) of benzenesulphonyl chloride (or 6 g. of p-toluenesulphonyl chloride) and 100 ml. of a 5 per cent, solution of sodium hydroxide. Stopper the flask and shake vigorously until the odour of the acid chloride has disappeared open the flask occasionally to release the pressure developed by the heat of the reaction. AUow the mixture to cool, and dissolve any insoluble material in 60-75 ml. of ether. If a solid insoluble in both the aqueous and ether layer appears at this point (it is probably the sparingly soluble salt of a primary amine, e.g., a long chain compound of the type CjH5(CH2) NHj), add 25 ml. of water and shake if it does not dissolve, filter it off. Separate the ether and aqueous layers. The ether layer will contain the unchanged tertiary amine and the sulphonamide of the secondary amine. Acidify the alkaline aqueous layer with dilute hydrochloric acid, filter off the sulphonamide of the primary amine, and recrystaUise it from dilute alcohol. Extract the ether layer with sufficient 5 per cent, hydrochloric acid to remove all the tertiary amine present. Evaporate the ether to obtain the sulphonamide of the secondary amine recrystaUise it from alcohol or dilute alcohol. FinaUy, render the hydrochloric acid extract alkaline by the addition of dilute sodium hydroxide solution, and isolate the tertiary amine. 

Treat 1 g. (1 ml.) of the amine with 4 mols of 10 per cent, sodium or potassium hydroxide solution (say, 20 ml,), and add 1 -5 mols (or 3 g. if the molecular weight is unknown) of benzenesulphonyl or p-toluenesulphonyl chloride in small portions with constant shaking. To remove the excess of acid chloride, either shake vigorously or warm gently. Acidify with dilute hydrochloric acid and filter off the sulphonamide. Recrystallise it from alcohol or dilute alcohol. 

Tile use of benzenesulphonyl chloride or of p-toluenesulphonyl chloride in the separation and identification of amines is described in Section IV,100. 

Esters of /i-toluenesulphonic acid, which are of great value as alkylating agents, may be prepared by interaction of p-toluenesulphonyl chloride and the alcdiol in the presence of sodium hydroxide solution or of pyridine, for example ... 

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°. 

Alternatively, grind 10 g. of p-toluenesulphonyl chloride to a fine powder and add it to 30 ml. of concentrated ammonia solution (sp. gr. 0-88). Heat the mixture to boiling (FUME CUPBOARD) and cool. Filter and recrystallise the p-toluenesulphonamide from boiling water (add 1 g. of decolourising carbon, if necessary). The yield of pme product, m.p. 138°, is almost theoretical. 

Commercial p-toluenesulphonyl chloride may be purified by dissolving it in benzene, washing with 6 per cent, sodium hydroxide solution, drying by shaking with anhydrous potassium carbonate or magnesium sulphate, and distilling under reduced pressure b.p. Hd /lS mm. m.p. 69°. The distillation should be completed without interruption. 

Thio-p-cresol (p-tolyl mercaptan), p-CHjCjH SH. This compound may be similarly prepared from p-toluenesulphonyl chloride (Section IV,207). The thio-p-cresol crystallises in the steam distillate and is collected and dried m.p. 43°. The b.p. under normal pressure is 194r-195°. 

An ethereal solution of diazomethane is usually prepared immediately before it is required for reaction. Two intermediates may be used for this purpose, viz., nitrosomethylurea and p-tolylsulphonylmethylnitrosamide a number of methods are available for obtaining the former the latter is prepared from methylamine and p-toluenesulphonyl chloride. Nitrosomethylurea is not very stable at room temperatures and must be kept at 0° on the other hand p-tolylsulphonylmethylnitrosamide is a stable solid, which can be kept for long periods at room temperature in a dark bottle. 

Tolylsulphonylmethylnitrosamide is obtained as follows. Interaction of p-toluenesulphonyl chloride and methylamine yields p toluenesulphonylmethyl amide ... 

In order to secure the maximum conversion of the methylamine into the sul-phonylmethylamide, the p-toluenesulphonyl chloride is introduced in several portions, and sodium hydroxide solution is added after each portion to liberate the methylamine from the hydrochloride formed in the reaction ... 

Reduction of a nitrosamine to a secondary amine. Proceed as for a nitro compound. Determine the solubility of the residue after evaporation of the ether and also its behaviour towards benzenesulphonyl (or p-toluenesulphonyl) chloride. 

The reaction of p-toluenesulphonyl chloride with toluene at 25 °C gave ditolyl sulphone and third-order kinetics, viz. 

It is generally more convenient to employ the solid p-toluenesulphonyl chloride (m.p. 69°) rather than the liquid benzenesulphonyl chloride. More-ova-, the benzenesulphonamides of certain secondary amines are oils or low melthig point solids that may be difficult to crystallise the p-toluenesulphon-amides usually have higher melting points and are more satisfactory as derivatives. Technical p-toluenesulphonyl chloride may be purified by dissolving it in benzene and precipitating with light petroleum (b.p. 40-60°). 

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