GB718502A - Polyacetal compounds - Google Patents

Abstract

Polyacetals useful as plasticizers for cellulose derivatives, e.g. cellulose acetate, cellulose nitrate and ethyl cellulose, are prepared by reacting a dialdehyde with a polyhydric alcohol or alkylene oxide. The reaction is preferably carried out in the presence of an acid catalyst for the alcohol reaction or a metal halide catalyst, e.g. stannic chloride, for the alkylene oxide reaction. The reaction may be effected at room or elevated temperatures and in the presence or absence of a solvent. Preferably one molar equivalent of polyhydric alcohol (corresponding to two free hydroxyl groups) or two moles of alkylene oxide are used per mole of dialdehyde. In examples: (1) 2-methoxymethyl-2:4 dimethylpentane-1:5 dial and ethylene glycol are reacted below 20 DEG C. in the presence of hydrogen chloride to give a colourless viscous liquid. A clear flexible sheet is obtained by casting from a mixture of a 16 per cent. acetone solution of cellulose acetate and an acetone solution of the polyacetal, the acetal/acetate ratio being 1:2; (2) As in (1) using different proportions to give a product which when cool is a hard clear resin, which may be used to plasticize cellulose acetate; (3) As in (2) but using phosphoric acid; (4) As in (1) but using (a) 1:3 cyclohexane dialdehyde, (b) 1:4 cyclohexane dialdehyde; (c) 2-ethoxymethyl-2:4 dimethyl pentane-1:5 dial; (5) Glycerol and 2-methoxymethyl-2:4 dimethylpentane-1:5 dial giving, after heating up to 180 DEG C. for many hours at low pressure, a dark semi-solid resinous material; (6) As in (5) with different proportions yielding a product softer, lighter coloured; (7) Pentaerythritol and 2-methoxymethyl-2:4 dimethylpentane 1:5 dial in the presence of phosphoric acid, giving a hard pale yellow resin; (8) As in (7) but using 2-ethoxymethyl-2:4-dimethylpentane-1:5 dial; (9) Pentaerythritol and a mixture of 1:3 and 1:4 cyclohexane dialdehydes giving a hard brown resin of very high melting point; (10) 2-methoxymethyl - 2:4 dimethylpentane - 1:5 dial and ethylene oxide in carbon tetrachloride and in the presence of stannic chloride to give the bis-cyclic acetal of ethylene glycol and 2-methoxymethyl - 2:4 dimethylpentane - 1:5 dial; (11) As in (10) using half the quantity of stannic chloride to give a small quantity of the product of example (10) and a semi-solid resin which may be used to plasticize cellulose acetate; (12) As in (10) but using twice the quantity of ethylene oxide to give some product as in (10) and a resin; (13) As in (10) but using (a) 1.3 cyclohexane dialdehyde; (b) 1.4 cyclohexane dialdehydes; (c) 2-ethoxymethyl-2:4-dimethylpentane - 1:5 dial; (14) Similar to (10) but using propylene oxide to give the corresponding bis-cyclic acetal; (15) 2-methoxymethyl - 2:4 - dimethylpentane - 1:5 - dial and pentamethylene glycol reacted in the presence of phosphoric acid; (16) As in (15) using twice the quantity of glycol to give a gel suitable for plasticizing cellulose acetate; (17) 2-methoxymethyl-2:4 dimethylpentane 1:5-dial added under reflux in four batches to glycerol and phosphoric acid in xylene to give, on extraction, a clear viscous material; (18) As in (17) but using 1.3 butylene glycol; (19) 2-methoxymethyl - 2:4 - dimethylpentane - 1:5 - dial, 4-vinyl cyclohexane - 1:2 - diol and phosphoric acid refluxed in xylene to give a viscous product; (20) As in (19) but using glycerol monocresyl ether; (21) As in (19) but using N-acetyl diethanolamine; (22) Pentaerythritol, ethylene glycol and 2-methoxymethyl-2:4-dimethylpentane-1:5-dial are refluxed in the presence of phosphoric acid to give hard resins. With increased proportions of glycol softer resins are obtained. The products of the examples may be used to plasticize cellulose acetate as in Example 1.ALSO:A bis-cyclic acetal of the formula <FORM:0718502/IV (b)/1> is obtained by reacting 43 parts of 2-methoxymethyl - 2 : 4 - dimethylpentane - 1 : 5 - diol and 11 parts ethylene oxide in the cold in the presence of 2 parts stannic chloride and 80 parts carbon tetrachloride. The reaction mixture is added to dilute sodium carbonate, the oil layer dried and distilled to give the acetal which is a clear mobile liquid boiling at 108-110 DEG C. at 1-2 mm. mercury. Using 200 parts of the diol, 58 parts of propylene oxide, 1 part stannic chloride and 160 parts carbon tetrachloride reacted at 50-60 DEG C. the corresponding homologue is obtained, boiling at 134-136 DEG C. at 10-12 mm. mercury.