Patent GB-671713-A (GB)
Title: Improvements in or relating to acetals of hydroxyl polymers
IPC: G03C7/327
Filed: 1950-01-20
Abstract: Polyvinyl acetals consisting of a polyvinyl alcohol acetalized with an alkyl or alkoxy substituted carbalkoxy - acetamido - benzaldehyde (see Group IV (c)) of the formula <FORM:0671713/IV (a)/1> where R is an alkyl group of 1-4 carbon atoms and X is an alkyl or alkoxy group of 1-4 carbon atoms, and optionally an aldehyde of the formula <FORM:0671713/IV (a)/2> where Y is a COOH or SO3H group or an alkali metal salt thereof, e.g. sulphobenzaldehyde and phthalaldehydic acid are made by reacting the vinyl alcohol polymer and the aldehyde or aldehydes or lower acetals thereof, i.e. one formed by reacting the aldehyde with an alkanol of 1 to 4 carbon atoms or a 1 : 2 alkanediol or a 1 : 2- or 1 : 3-glycol, in the presence of an acid catalyst, e.g. phosphoric acid.  Preferably the polymer and aldehydes are dissolved in an organic solvent, e.g. acetone, methyl ethyl ketone, methanol, ethanol and mixtures and after the reaction the slurry is treated with a compound capable of neutralizing the acid catalyst, e.g. alkali or alkaline earth metal bicarbonates or carbonates, triethylamine, triethanolamine, diethylamine, quinoline, and pyridine.  The polymers may be the fully or partially hydrolysed polymers of vinyl acetate, propionate or benzoate or copolymers of these esters with other monomers such as ethylene or isobutylene and if desired the alcohols may be modified by the introduction of acetal, ester and ether groups.  Specified compounds of the above formula are 4-methoxy, 4-methyl, 4-ethoxy, 4-butoxy, 4-ethyl, and 4-tertiarybutyl - 3 - carbethoxyacetamidobenzaldehyde and the ethylene glycol acetals.  The acetals are used as colour-formers in photography (see Group XX).  Specifications 627,125, [Group IV (b)], 635,294, 638,895, 652,928 and 665,657, [Group XX], are referred to.ALSO:Alkyl or alkoxy substituted carbalkoxy-acetamido-benzaldehydes of the formula <FORM:0671713/IV (b)/1> where R is an alkyl group of 1-4 carbon atoms and X is an alkyl or alkoxy group of 1-4 carbon atoms, or a lower acetal thereof, i.e. one formed with an alkanol of 1-4 carbon atoms or a 1 : 2-alkanediol or a 1 : 2- or 1 : 3-glycol of 2-4 carbon atoms, are made by reacting a carbethoxyacetyl chloride, e.g. carbomethoxy-or carbethoxyacetyl chloride, with a lower acetal of an alkyl or alkoxy substituted o-, m-, or p-aminobenzaldehyde in an organic solvent, e.g. acetone, precipitating the resulting acetal and isolating, if desired, the free aldehyde from the acetal by acid hydrolysis.  In examples, 4-methoxy - 3 - carbethoxyacetamidobenzaldehyde ethylene glycol acetal is made by reacting 4 - methoxy - 3 - aminobenzaldehyde ethylene glycol acetal with carbethoxyacetyl chloride, and 4 - methyl - carbethoxyacetamidobenzaldehyde ethylene glycol acetal by reacting 4-methyl-3-aminobenzaldehyde ethylene glycol acetal with carbethoxyacetyl chloride.  Other specified acetals are 4-ethoxy, 4-butoxy, 4-ethyl, 4-t.-butyl-carbethoxyacetamidobenzaldehyde ethylene glycol acetal, 4-methoxy-3-carbomethoxyacetamidobenzaldehyde ethylene glycol acetal, and 4-methoxy-3-carbo-n-butoxyacetamidobenzaldehyde ethylene glycol acetal.  Specifications 627,125, 635,294, 638,895, 652,928 and 665,657, [Group XX], are referred to.