2-Hydroxy,alkoxy,methylolbenzophenone intermediate compounds for the manufacture of improved copolymerizable ultraviolet light absorber compounds

DETAILED DESCRIPTION OF THE INVENTION The intermediate compounds of the invention are made by formylation of a 2-hydroxy,alkoxybenzophenone starting material having the formula: ##STR3## where R is alkyl C.
sub.
1 -C.
sub.
8, with formaldehyde in aqueous alkaline solution at a pH of about 12-13, and at a temperature of less than 40.
degree.
C.
, preferably at room temperature, using a water-miscible organic solvent to keep the benzophenone in solution.
An alkyl group is defined herein as being either straight chain or branched, including methyl, ethyl, propyl, butyl, octyl, isopropyl, isobutyl and the like.
During the formylation reaction, an excess of formaldehyde in the reaction mixture prevents side reactions from occurring, thus increasing the yield of the desired methylol product.
Accordingly, when the molar ratio of benzophenone to formaldehyde is adjusted to 1:1, a yield of about 70% of predominately the 5-monomethylol intermediate is obtained during a 24-hour reaction period.
On the other hand, by using a ratio with an excess of formaldehyde, e.
g.
, about 1:3, the yield of methylol compounds is about 95%.
The product is a mixture of the 5- and 3-monomethylol compounds, in about a 60:40 ratio of each, and some 3,5-dimethylol compound, during a 51/2 hour reaction period.
Still higher ratios may be used, too, but the substantial excess of formaldehyde must be separated from the reaction products, which is undesirable.
The concentration of the reactants is not critical.
Generally they are made low enough to keep them in solution but sufficiently high to enable the reaction to proceed at a reasonable reaction rate.
Usually the benzophenone is present at a concentration of about 30% by weight, and the formaldehyde about 10% by weight of the solution.
The alkali is present at a concentration of about 10%.
After the methylol intermediate is formed, the reaction product mixture is acidified and washed with water.
Then unreacted formaldehyde, which is present in the organic phase, is removed under vacuum