Patent GB-661477-A (GB)
Title: Improvements in or relating to lower acetals of substituted benzaldehydes
IPC: C07C43/30
Filed: 1949-02-28
Abstract: Polyvinyl acetals are prepared by reacting a compound of one of the general formul  <FORM:0661477/IV (a)/1> and <FORM:0661477/IV (a)/2> wherein R1, R2, R3 and R4 are the same or different and are hydrogen or halogen atoms or aliphatic or alkoxy radicals of 1 to 4 carbon atoms, R5 is H, an alkyl radical of 1 to 6 carbon atoms, or an aryl radical of 6 to 10 carbon atoms, and G is a hydrogen or halogen atom or a carboxylic or sulphonic acid group, or a corresponding acetal containing up to 4 carbon atoms in the acetal group, including cyclic acetals such as ethylene glycol acetals, with a polyvinyl alcohol or ester, e.g. by stirring together the aldehyde and polyvinyl alcohol in suspension or solution in an organic or aqueous organic solvent containing a catalytic amount of a strong acid.  The acetals may be formed from hydrolysed copolymers of vinyl esters with other vinyl monomers.  From 0.75 to 7.5 per cent of the hydroxyl groups of the polyvinyl alcohol may be acetalized, and from 0.1 to 5 per cent of the hydroxyl groups may be acetalized with an aldehydo-acid, e.g. o-sulphobenzaldehyde or phthalaldehydic acid. Acetals from polyvinyl alcohol and m-(3-methylsalicylamido)-benzaldehyde, which may be used as colour formers in photographic processes, are referred to. Specification 535,341 is referred to.ALSO:Lower acetals of compounds of the general formula <FORM:0661477/IV (b)/1> and <FORM:0661477/IV (b)/2> wherein R1, R2, R3 and R4 are the same or different and are hydrogen or halogen atoms or aliphatic or alkoxy radicals of 1 to 4 carbon atoms, R5 is H, an alkyl radical of 1 to 6 carbon atoms, a cyclohexyl radical, or an aryl radical of 6 to 10 carbon atoms, and G is a hydrogen or halogen atom or a carboxylic or sulphonic acid group, are prepared by condensing a compound of one of the formul <FORM:0661477/IV (b)/3> and <FORM:0661477/IV (b)/4> wherein X is a halogen atom, with a lower acetal of a compound of the formula <FORM:0661477/IV (b)/5> The corresponding aldehydes are prepared by hydrolysis of the lower acetals.  m - (3 - Allylsalicylamido) - benzaldehyde is prepared by adding 3-allylchloride dropwise to a cooled suspension of anhydrous potassium carbonate and m-aminobenzaldehyde ethylene glycol acetal in water and acetone, and adding hydrochloric acid to a heated acetone solution the product. m-(3-Allyl-4-methylsalicylamido)-benzaldehyde, m - (3 - isopropyl - 6 - methylsalicylamido)-benzaldehyde, m-salicylamidobenzaldehyde ethylene glycol acetal, m-(4-methylsalicylamido) - benzaldehyde ethylene glycol acetal, m - (3 - methylsalicylamido) - benzaldehyde ethylene glycol acetal, m-(3 : 6-dimethylsalicylamido)-benzaldehyde ethylene glycol acetal, m-(6-chloro - 3 - methylsalicylamido) - benzaldehyde ethylene glycol acetal, m-(4-chloro-3-methylsalicylamido)-benzaldehyde ethylene glycol acetal, and m - (3 - hydroxy - 4 - methylbenzamido) - benzaldehyde ethylene glycol acetal are similarly prepared. Other acyl chloride reactants that may be used are 3-ethyl-2-hydroxybenzoyl chloride, 3 - propyl - 2 - hydroxybenzoyl chloride, 3 - isopropyl - 2 - hydroxybenzoyl chloride, 3-hydroxy-2 - allylbenzoyl chloride, 3 - hydroxy - 4 - allylbenzoyl chloride, 2 : 4-diallyl-3-hydroxybenzoyl chloride, 6-methylsalicylyl chloride, and 3-hydroxy-5-methylbenzoyl chloride, and other aldehyde reactants that may be used are o- and p-aminobenzaldehyde, 3-amino-4-chlorobenzaldehyde, 5-amino-2-chlorobenzaldehyde, 3-amino - 4 - methylbenzaldehyde, 3 - amino - 4 : 6 - dichlorobenzaldehyde, and 3 - amino - 4 - methoxybenzaldehyde.  Instead of the aminobenzaldehyde, acetals derived from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, 1 : 3-propylene glycol, 1 : 2-propylene glycol, and 1 : 3-butylene glycol may be employed.  3-Allylsalicylyl chloride is prepared by adding pyridine dropwise to a mixture of 3-allylsalicylic acid and thionyl chloride. 3-Allyl-4-methylsalicylyl chloride, 2 - ethylcarbonato - 3 - isopropyl - 6 - methylbenzoyl chloride, 2 - acetoxybenzoyl chloride, 2 - acetoxy - 4 - methylbenzoyl chloride, 3-methylsalicylyl chloride, 3 : 6-dimethyl-2-ethylcarbonatobenzoyl chloride, and 3-acetoxy-4-methylbenzoyl chloride are similarly prepared.  2 - Ethylcarbonato - 3 - isopropyl - 6 - methylben-oic acid is prepared by stirring together 3 - isopropyl - 6 - methylsalicylic acid, dioxane, ethyl chlorocarbonate, and diethylaniline.  3 : 6 - Dimethyl - 2 - ethylcarbonatobenzoic acid is similarly prepared. Specification 535,341 is referred to.