Patent GB-594008-A (GB)
Title: Manufacture of polymerisable compounds and of polymers therefrom
IPC: C07D339/08
Filed: 1945-01-08
Abstract: Halogen-free polymerizable compounds are prepared by reacting with an aqueous solution of a hydrosulphide of an alkali-metal on a monohalogen substituted aliphatic ketone or on a dihalogen substituted aliphatic ketone in which the halogens are attached to different carbon atoms and are in the alpha or beta position to the carbonyl group, said halogen being chlorine, bromine or iodine.  The products are stated to be novel mono- or di-mercapto-ketones and are formed as monomers or low molecular weight addition polymers, i.e. containing not more than four units.  The reaction is preferably carried out in the presence of a water-immiscible inert organic liquid whereby the mercaptoketones are removed from the sphere of reaction as soon as they are formed, so avoiding thio-ether formation; the latter may also be avoided by lowering the temperature and/or increasing the pressure at which reaction is effected.  The monomeric mercapto-ketones form the addition polymers on standing; thus, mono- or di-mercapto acetone in benzene deposits a dimeric addition polymer of the mercapto-ketone.  The low molecular weight addition polymers of di-mercaptoacetone are converted to the monomeric form on warming with dilute acid.  The monomeric mono- and di-mercapto ketones and their low molecular weight addition polymers are converted into condensation polymers by effecting auto-condensation in the presence of an acid-reacting condensation catalyst comprising dry hydrochloric acid, sulphuric acid containing not more than 20 per cent by weight of water, or a Friedel-Crafts catalyst, or in the presence of an excess of an oxidising agent, for example, iodine.  The mercapto-ketones may be partially oxidised using an amount of oxidising agent which is less than that molecularly equivalent to the mercapto-ketone and then polymerized as above.  The fusible polymers may be moulded, for example, in the form of threads and then further polymerized. The solubility characteristics of the polymers may be altered by treatment with aqueous acid permanganate.  In examples: (1) monomeric dimercapto acetone is prepared by shaking a benzene solution of sym.-dichloracetone with an aqueous solution of sodium hydrosulphide for two minutes with cooling, extracting the benzene layer with aqueous trisodium phosphate so obtaining an aqueous solution of the sodium salt of the mercapto-ketone which is mixed with benzene and sodium dihydrogen phosphate to give a benzene solution of dimercaptoacetone, which is isolated as a viscous oil on distilling off the solvent; (2) a low molecular weight addition polymer of dimercapto-acetone is prepared by the procedure of (1) above, the period of shaking being 15 mins. whereupon colourless crystals of the polymer separate; (3) the procedure of (2) is repeated, the mixture being seeded or allowed to stand for 16 hours; (4) the polymer of (2) above is prepared by adding lumps of fused dichloracetone to aqueous sodium hydrosulphide with shaking at below 5 DEG  C., the crystalline polymer then separating out on standing; the addition polymer is depolymerized (a) by warming with N-sulphuric acid or (b) melting with a solid mixture of phosphoric acid and potassium dihydrogen phosphate; (5) a low molecular weight polymer of mono-mercaptoacetone is prepared by shaking a benzene solution of monochloracetone with aqueous sodium hydrosulphide; the product is believed to undergo a cis-trans conversion on treatment with concentrated aqueous hydrochloric acid or a mixture of glacial acetic and sulphuric acids; (6) mercaptomethyl b -mercaptoethyl ketone is prepared by shaking chlormethyl b -chloroethyl ketone with aqueous sodium hydrosulphide; (7) the addition polymer of dimercapto acetone is melted and gaseous hydrochloric acid bubbled through yielding a fusible resin capable of being drawn into threads; (8) the addition polymer of mercaptoacetone is converted into an infusible resin with 98 per cent sulphuric acid; (9) the depolymerized product of 4 (b) is extracted with benzene and the solution treated with 80 per cent sulphuric acid; the white powdery precipitate is rendered a water-soluble polymer by treatment with acid permanganate; (10) the product of (5) is converted into a rubbery mass by means of 98 per cent sulphuric acid and on kneading with boiling water forms a mass capable of being drawn into threads; (11) the product of (6) is converted into a red resin by 98 per cent sulphuric acid and is also capable of being drawn into threads.