Patent GB-583225-A (GB)
Title: Process for the polymerisation of 6-membered cyclic formals
IPC: C08G4/00
Filed: 1943-10-20
Abstract: Polymeric materials for use in lacquers, varnishes or shellacs are obtained by treating at an elevated temperature a 1 : 3-dioxane of not more than seven carbon atoms and having the general formula <FORM:0583225/IV/1> wherein R1, R2, R5 and R6 represent hydrogen, methyl, ethyl, hydroxymethyl, dihydroxyethyl or trihydroxypropyl radicals, R3 represents a hydrogen, methyl, ethyl, hydroxymethyl or dihydroxyethyl radical and R4 represents a hydrogen, hydroxyl, hydroxymethyl or dihydroxyethyl radical, with a composition comprising a catalyst capable of cleaving the 6-membered ring and a catalyst capable of polymerizing the cleavage products.  Suitable cleavage catalysts are acid halides, e.g. chlorides of acetic, propionic and butyric acids; alkyl sulphates, e.g. dimethyl sulphate; hydrogen halides, e.g. hydrochloric acid; and phosphorus halides and oxyhalides. Suitable polymerization catalysts are of the Friedel-Crafts type, e.g. boron trifluoride, stannic chloride, aluminium chloride, aluminium bromide, zinc chloride, ferric chloride, antimony pentachloride, antimony trichloride, titanium trichloride, titanium tetrachloride, zirconium tetrachloride and mercuric chloride.  The starting-materials may be obtained by reacting formaldehyde with trimethylene glycol; glycerol; 1,3 - butylene glycol; 2-methyl propanediol-1,3; pentanediol-1,3; pentanediol-2,4; 2,2-dimethyl propanediol-1,3; 2-ethyl propanediol-1,3; 2-methyl butanediol-1,3; 3-methyl butanediol-1,3; erythritol; pentaerythritol; and the various pentitols and hexitols. The polymerization catalyst may be dissolved in a solvent, e.g. chloroform, which also dissolves the monomer, the cleavage catalyst added and the mixture refluxed.  Other suitable solvents are acetic acid and methanol.  Or the polymerization catalyst may be dissolved in the monomer, and the cleavage catalyst added before refluxing. The polymerization catalyst is 5-100 per cent of the weight of the monomer and the cleavage catalyst 0.1-2.0 per cent thereof.  The temperature may range from 25-200 DEG  C.  The products may be purified by washing with alkali, e.g. sodium carbonate or hydroxide or with suitable organic solvents.  The products may be used in admixture with urea-formaldehyde resins, phenol-formaldehyde resins, nitrocellulose, cellulose acetate, polyvinyl resins, polyacrylate resins, or glyptal type resins.  Incorporated into drying oil-alkyd resins they give fast-drying, non-wrinkling compositions which do not need organic driers.  In example 1, boron trifluoride, acetic acid, 4-methyl-1,3-dioxane, and acetyl chloride are refluxed for 2 days, the mixture cooled and diluted with water.  The precipitate is filtered off, washed with water and dried.  Solutions of the product yielded clear, hard films. Example (2) is similar, but employs hydrochloric acid as cleavage catalyst and methanol as solvent.  In example (3), chloroform is employed as the solvent and the polymer finally separated from its chloroform solution by addition of petroleum ether.  It is soluble in halogenated hydrocarbon solvents. Example (4) dispenses with a solvent altogether.  Example (5) is similar to example (4), but employs stannic chloride in place of boron trifluoride.  Example (6) polymerizes 4-methyl-1,3-dioxane in absence of solvent with a catalyst mixture of zinc chloride and hydrochloric acid.  In example (7), 1,3-dioxane is polymerized in acetic acid solution using boron trifluoride and acetyl chloride as the solvents.  The Specification as open to inspection under Sect. 91 includes as starting-material six-membered cyclic acetals in which the 1 and 3 hetero atoms are oxygen or sulphur, the majority of compounds falling within the general formula <FORM:0583225/IV/2> wherein R1 represents hydrogen, alkyl, aralkyl and aryl groups which may be the same or dissimilar; R2 represents hydrogen, hydroxyl, alkyl, aralkyl and aryl groups which may be the same or dissimilar and A is oxygen or sulphur.  The products may be obtained by condensation of an aldehyde with any of the bodies mentioned above or with resorcinols, propane-dithiol-1,3; butanedithiol-1,3; pentanedithiol-2,4; 2-ethyl-hexanedithiol-1,3; or thioresorcinol. This subject-matter does not appear in the Specification as accepted.