Patent GB-404317-A (GB)
Title: Improved process for the manufacture of organic condensation products
IPC: C08G6/02
Filed: 1932-07-12
Abstract: Synthetic resins are manufactured from condensation products of formaldehyde, paraformaldehyde or trioxymethylene with acetone or other methyl ketone or a condensation product thereof containing oxygen and formed with or without elimination of water (e.g. mesityl oxide or diacetone alcohol respectively), by distilling them under diminished pressure, rectifying the total distillate obtained so as to produce at least two fractions, and polymerizing or permitting to polymerize that fraction which, as found on trial, yields a hard, clear, colourless or nearly colourless, glassy resin.  The condensation products employed as starting materials are preferably prepared by allowing an approximately equimolecular mixture of the reactants to remain in the presence of an alkaline catalyst, e.g. hydroxides of alkali or alkaline earth metals or organic bases such as trialkylamines or quaternary bases, e.g. tetramethylammonium hydroxides, at a temperature low enough to prevent the mixture developing a brown colour (generally about 25 DEG  C. but sometimes at refluxing temperature).  In examples: (1) acetone and aqueous formaldehyde are condensed in the presence of barium hydroxide below 30 DEG  C. and the catalyst is then removed by adding sulphuric acid or passing in carbon dioxide; the product, after removal of excess acetone and water by distillation, preferably under vacuum, is distilled under 16 mm. pressure, the total distillate is fractionally distilled at the same pressure (three fractions being collected, of which the 2 : 4-dinitrophenylhydrazones are described) and the fraction boiling at 90--95 DEG  C. is polymerized, with or without the aid of sunlight or ultra-violet light, or of polymerizing agents such as organic peroxides, e.g. benzoyl peroxide, or hydrogen peroxide or its compound with urea; an increase in yield of the resin may be obtained by adding an alkylamine, e.g. trimethylamine or di- or triethylamine, to the total distillate before fractionation; (2) acetone and aqueous formaldehyde are condensed in the presence of sodium hydroxide at 25--35 DEG  C. and the catalyst is neutralized with hydrochloric acid; the product is treated as in (1) except that only two fractions are collected, that boiling at 90--110 DEG  C..16 mm. polymerizing spontaneously; (3) acetone and aqueous formaldehyde are refluxed in the presence of triethylamine, excess acetone, water and triethylamine are distilled off under 40 mm. pressure and the product is treated as in (1).  The Provisional Specification contains the following additional subject-matter: (a) trimethylsulphonium hydroxide is specified as a catalyst in the initial condensation; (b) the volatile products of the condensation may be acylated to produce substances useful as plasticizers; (c) the non-volatile products, e.g. the distillation residue in example (1), are useful as constituents of lacquers or varnishes, particularly after heating with colophony to about 280 DEG  C.; (d) in example (3) the distillate may be collected as one fraction, which separates into two layers the lower of which polymerizes; (e) in additional examples: (4) mesityl oxide and aqueous formaldehyde are refluxed in the presence of sodium hydroxide with the addition of methanol, the liquid separates into two layers and the lower one is heated in vacuum to produce a brown friable resin; (5) mesityl oxide and aqueous formaldehyde are condensed in the presence of sodium hydroxide below 45 DEG  C. and two layers separate, the upper of which is fractionally distilled under 16 mm. pressure.