Formaldehyde and its applications / Synthite Limited.

Synthite Limited.

Date:: [Between 1930 and 1939?]

Catalogue details

Licence: Public Domain Mark

Credit: Formaldehyde and its applications / Synthite Limited. Source: Wellcome Collection.

29/36 page 27

Fortunately, these react generally as formaldehyde and can usually be ignored, but they may have some influence on more intricate processes, and the chemically heterogeneous nature of ordinary formaldehyde solutions should be kept in mind. The proportions and composition of these polymeric forms is probably determined by the initial method of manufacture and also to a lesser extent by the time and temperature of storage, while the amount of alcohol and impurities present are also-certain to have some effect. ; When formalin is evaporated to dryness, a white mass of poly- merised formaldehyde is obtained, which, when reduced to a fine powder, forms the paraformaldehyde of commerce. This consists of a number of complex polymers (CH.O)}n together with hydrated forms (CH,O)n H,O, where “‘n’’ is probably 6 to 8. When evaporation is carried out in the presence of a dehydrating agent, the principal product obtained is trioxymethylene (CH,O),, a definite crystalline compound fusing at 171-172°C., and insoluble in water, alcohol, and ether at ordinary temperatures. Much work has been done on the various polymers of formaldehyde, Auerbach and Barschall claim to have established the identity of at least. six Paraformaldehydes (CH,O)n H.O; four polyoxymethylenes (CH,O)n and Trioxymethylene C,;H,O; of ring structure. Commercially, both trioxymethylene and paraformaldehyde are synonymous terms though from a strictly chemical point of view this confusion is deplorable. The paraformaldehyde generally marketed is a mixture of partly dehydrated polymers containing 95—97% ‘*formaldehyde’’ the remainder being loosely combined water which it 1s not economic to remove. Page Twenty-seven a SYNTNTE Thee WENT PROrte ie

digitised image 1

digitised image 2

digitised image 3