Preparation of Vanillin from Peat

Benzaldehydes Chapter 15 Preparation of Vanillin from Peat 

100 kg. of dry peat powder are mixed with a solution of 30 kg. of chromic acid in 700 kg. glacial acetic acid and oxidised by heating for 10 to 15 hours at a temperature of 40° C. After addition of 30 kg. of concentrated sulphuric acid the mixture is then boiled for 10 hours under reflux. From the solution separated from the crude fibre the sulphuric acid is removed by addition of the corresponding quantity of baryta acid 600 litres of the glacial acetic acid are removed by vacuum distillation. After diluting the residue with 200-litres of common salt solution the vanillin is extracted with ether and purified in the usual way. The yield amounts to about 0.9 kg. of crystallised vanillin. 

A further 0.2 kg. of vanillin may be extracted from the acetic acid which has been removed by distillation. The yields obtained when using other substances in place of dry peat powder are as follows  

Ozone having a concentration of 5—8% is led into a well stirred mixture of 20 kg. of pinewood sawdust in 100 kg. of glacial acetic acid at room temperature until the wood is completely bleached. Seventy litres of the glacial acetic acid are then removed by vacuum distillation and the mixture remaining is diluted with water to its original volume. After addition of 0.3 kg. of sulphuric acid, the whole is hydrolysed by boiling under reflux and the solution and residue are further treated as in the preceding example. The yield of crystallised vanillin is about 2 kg. 

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