Benzenesulphonic chloride

The potassium benzenesulphonate is carefully dried on the water-bath, powdered, and mixed with the phosphorus pentachloride in a flask. A vigorous reaction sets in. When it hats abated, the flask is heated on the water-bath for one hour, and the mass occasionally stirred with a glass rod. The product is poured into a flask containing 200 c.c. cold water and allowed to stand an hour. The sulphonic chloride, which separates as an oil, is then extracted with ether, dehydrated over calcium chloride, decanted, and the ether removed on the water-bath. Yield, 10 grams of a light brown oil. 

Properties.—Colourless oil when pure b. p. 246—247° with decomposition m. p. 14 distils undecoinposed m vacieo. 

---

In place of benzoyl chloride, other chlorides, eg., phenylacetyl chloride, or benzenesulphon chloride, can be used, which act in a similar way. Acetyl derivatives may also be prepared in the presence of alkalies in water solution, only in this case acetic anhydride and not the easily decomposed acetyl chloride is used. At times the reaction takes place better by using potassium hydroxide in place of sodium, hydroxide. 

Benzenesulphonyl Chloride, C6HBSO2CI, which is also called benzenesulphon chloride, is an oil, insoluble in water, which possesses a characteristic odor. It boils with decomposition at 247° but distils unchanged at 120° under a pressure of 10 mm. 

A further difference between aliphatic and aromatic hydrocarbons is that only the latter are capable of direct sulphonation. Thus benzene when heated with concentrated sulphuric acid gives benzenesulphonic acid, a reaction which proceeds more readily, however, if chlorosulphonic acid is used instead of sulphuric acid an excess of chlorosulphonic acid however may convert the sul phonic acid into the sulphonyl chloride (c/. p. 181). 

The high sodium ion concentration results in facile crystallisation of the sodium salt. This process of salting out with common salt may be used for recrystallisation, but sodium benzenesulphonate (and salts of other acids of comparable molecular weight) is so very soluble in water that the solution must be almost saturated with sodium chloride and consequently the product is likely to be contaminated with it. In such a case a pure product may be obtained by crystallisation from, or Soxhlet extraction with, absolute alcohol the sul-phonate is slightly soluble but the inorganic salts are almost insoluble. Very small amounts of sulphones are formed as by-products, but since these are insoluble in water, they separate when the reaction mixture is poured into water ... 

In a 500 ml. bolt-head flask, provided with a mechanical stirrer, place 70 ml. of oleum (20 per cent. SO3) and heat it in an oil bath to 70°. By means of a separatory funnel, supported so that the stem is just above the surface of the acid, introduce 41 g. (34 ml.) of nitrobenzene slowly and at such a rate that the temperature of the well-stirred mixture does not rise above 100-105°. When all the nitrobenzene has been introduced, continue the heating at 110-115° for 30 minutes. Remove a test portion and add it to the excess of water. If the odour of nitrobenzene is still apparent, add a further 10 ml. of fuming sulphuric acid, and heat at 110-115° for 15 minutes the reaction mixture should then be free from nitrobenzene. Allow the mixture to cool and pour it with good mechanical stirring on to 200 g. of finely-crushed ice contained in a beaker. AU the nitrobenzenesulphonic acid passes into solution if a little sulphone is present, remove this by filtration. Stir the solution mechanically and add 70 g. of sodium chloride in small portions the sodium salt of m-nitro-benzenesulphonic acid separates as a pasty mass. Continue the stirring for about 30 minutes, allow to stand overnight, filter and press the cake well. The latter will retain sufficient acid to render unnecessary the addition of acid in the subsequent reduction with iron. Spread upon filter paper to dry partially. 

Method 2. Place 90 g. of sodium benzenesulphonate (Section IV,29) (previously dried at 130-140° for 3 hours) and 50 g. of powdered phosphorus pentachloride (1) in a 500 ml. round-bottomed flask furnished with a reflux condenser heat the mixture in an oil bath at 170-180° for 12-15 hours. Every 3 hours remove the flask from the oil bath, allow to cool for 15-20 minutes, stopper and shake thoroughly until the mass becomes pasty. At the end of the heating period, allow the reaction mixture to cool. Pour on to 1 kilo of crushed ice. Extract the crude benzenesulphonyl chloride with 150 ml. of carbon tetrachloride and the aqueous layer with 75 ml. of the same solvent. Remove the solvent under atmospheric pressure and proceed as in Method 1. The yield is about 170 g., but depends upon the purity of the original sodium benzenesulphonate. 

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°. 

Some interesting results have been obtained by Akand and Wyatt56 for the effect of added non-electrolytes upon the rates of nitration of benzenesulphonic acid and benzoic acid (as benzoic acidium ion in this medium) by nitric acid in sulphuric acid. Division of the rate coefficients obtained in the presence of nonelectrolyte by the concentration of benzenesulphonic acid gave rate coefficients which were, however, dependent upon the sulphonic acid concentration e.g. k2 was 0.183 at 0.075 molal, 0.078 at 0.25 molal and 0.166 at 0.75 molal (at 25 °C). With a constant concentration of non-electrolyte (sulphonic acid +, for example, 2, 4, 6-trinitrotoluene) the rate coefficients were then independent of the initial concentration of sulphonic acid and only dependent upon the total concentration of non-electrolyte. For nitration of benzoic acid a very much smaller effect was observed nitromethane and sulphuryl chloride had a similar effect upon the rate of nitration of benzenesulphonic acid. No explanation was offered for the phenomenon. 

The addition of copper to a boiling solution of benzenesulphonyl azide in methanol gave benzenesulphonamide 18 (80%) as the major product together with minor amounts of methylenebis(benzenesulphon-amide) 22 and 1,3,5-tris (benzenesulphonyl) hexahydro-s-triazine 23, resulting from condensation of 18 with the formaldehyde formed in the reaction 33>. Cuprous chloride was even more effective, but cuprous... 

Cationic accelerants vary in their efficacy [161]. Other types of accelerant have also been evaluated. In one study [162], comparisons were made between tetra-ethylammonium bromide, benzyltriethylammonium chloride, polyfdiallyldimethylammonium chloride) and the diethyldimethylammonium derivative of a benzenesulphonate polyglycol ester. It was found that the cationic polymers had a greater effect than the simple quaternary ammonium compounds of lower molecular mass. This effect was attributed to the capability of the polymers to enter into hydrophobic interaction with the fibre surface. Ethylenediamine has also been found to accelerate the alkaline hydrolysis of polyester [163]. 

On Sulphonyl Chlorides and Sulphonamides.—The conversion of benzenesulphonic acid into its chloride and amide shows that derivatives of sulphonic acids, analogous to those of carboxylic acids, can be obtained. The sulpho-chlorides are much less reactive than are the chlorides of the carboxylic acids benzene sulphochloride, for example, can be dis-stilled in steam almost without decomposition. 

Kobayashi, N. and Ando, H. (1988fc). Monoazo lake for printing inks etc.—prepared by diazotizing 2-amino-5-methyl benzenesulphonic acid, coupling with 2-hydroxy-3-naphtholic acid and adding barium chloride solution. Dainippon Inc. Patent JP63-225 667 Chem. Abstr, 110, 77504. [26It]... 

In order to obtain pure sodium benzenesulphonate, 5 grammes of die crude product is crystallised from absolute alcohol, upon which it is noticed that the sodium chloride mixed with it is insoluble in alcohol. 

The sulphonic acid formed can be separated in the form of a salt by either of the methods described below. In the first method (a), which in the case of benzenesulphonic acid is simpler, advantage is taken of the fact that sodium benzenesulphonate is insoluble in a solution of sodium chloride. The second method (.b) is the one commonly used to isolate sulphonic acids. It is... 

Preparation of Benzenesulphonyl Chloride (SECTION 473).—Convert all of the salt of benzenesulphonic acid obtained in experiment 173 above into benzenesulphonyl chloride as follows HOOD. Place the dry salt in a flask and add phosphorus pentachloride, which should be weighed in the hood, in the proportion of 3 parts by weight of the salt to 4 parts by weight of the chloride. Heat the mixture on the steam-bath, with occasional shaking, for half an hour. Cool, and add to the liquid about ten times its volume of ice-water. Shake about every 10 minutes in order to facilitate the reaction of the phosphorus oxychloride present with water. At the end of an hour... 

---