Acetaldehyde bisulphite compound

Much of the sulphur dioxide present in beer is in a bound form, for example, as the acetaldehyde bisulphite compound. The classical (Monier-Williams) method for the estimation of sulphur dioxide, adopted by the Institute of Brewing, involves the removal of SO2 from acidified beer in a stream of carbon dioxide and nitrogen at 100 C. The gas is absorbed in hydrogen peroxide and the sulphuric acid formed titrated. In Britain sulphur dioxide is a permitted preservative in beers ( > 70 ppm), ciders, and wines ( > 150 ppm) and the Monier-Williams method is official. The EBC-ASBC adopt a more sensitive colorimetric method in which the colour restored to acid-decolourized rosaniline hydrochloride is measured. 

Cinnamic aldehyde, C HgO, is the principal odorous constituent of dnnamon and cassia oils, and is manufactured to a considerable extent, artificially. It can be extracted from the oils in which it occurs by means of sodium bisulphite, the sodium bisulphite compound being decomposed with dilute sulphuric acid, and distilled in a current of steam. The preparation of artificial cinnamic aldehyde, which is used in perfumery as a substitute for the natural oils, is usually carried out. by a condensation of benzaldehyde and acetaldehyde, according to the following reaction —... 

This reaction was exploited in Germany in 1914-1918 by adding compounds (e.g. bisulphite) to complex acetaldehyde. Under these conditions glycerol was produced for the manufacture of explosives such as trinitroglycerol. 

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