Sodium—continued bisulphite

Introduce a solution of 100 g. of sodium bisulphite in 200 ml. of water and continue the stirring, preferably for 10 hours with exclusion of air. A thick precipitate separates after a few minutes. Collect the bisulphite compound by suction filtration, wash it with ether until colourless, and then decompose it in a flask with a lukewarm solution of 125 g. of sodium carbonate in 150 ml. of water. Separate the ketone layer, extract the aqueous layer with four 30 ml. portions of ether, dry the combined organic layers over anhydrous magnesium sulphate, remove the ether at atmospheric pressure, and distil the residual oil under reduced pressure from a Qaisen flask with fractionating side arm (Fig. II, 24, 5). Collect the cyclo-heptanone at 64r-65°/12 mm. the yield is 23 g. 

According to one patent,1 dilute sodium bisulphite is electrolysed in the cathode compartment, and the addition of neutral chloride or sulphate is recommended in order to increase the yield. During electrolysis the temperature should be kept at 0-5° C. and sulphurous acid added to the electrolyte continuously. 

Dealing with the sulphosuccinate diester synthesis, the esterification procedure is performed very similar to that described above for monoesters but the feed of hydroxyl-bearing material (generally Ce-u alcohols) should be twice more with respect to maleic anhydride. The first step is performed under a gradually increasing temperature to 120-150 °C and with continuous vacuum distillation of water from esterification. At that step esterification catalyst may be used, such as /7-toluenesulphonic acid or ABSA. The sulphonation with sodium bisulphite proceeds as described above. A representative example of diesters is sodium bis(2-ethylhexyl) sulphosuccinate known as Aerosol OT of the formula ... 

To the remaining sample and standard solutions add, in order, 15 ml of buffer solution pH 7 5, 2 ml of 10 per cent sodium bisulphite and 3 ml of 0-4N sodium hydroxide. Place the flasks in boiling water for exactly five minutes, add 12 ml of 5N hydrochloric acid, mix and continue heating for a further two minutes. Cool the flasks immediately. Dilute all solutions to volume with water and measure the extinctions of the acid-treated sample and standard solutions at 445 mju in a 1-cm... 

---