Patent GB-647466-A (GB)
Title: Improvements in or relating to the production of anthracene derivatives
Filed: 1946-11-22
Abstract: Anthracene adducts are obtained by reacting anthracene with an ester obtained by reacting a carboxylic acid having alpha, beta unsaturated olefinic bonds with a monohydric saturated aliphatic alcohol containing at least two carbon atoms.  The same adducts are also obtained by reacting anthracene first with the carboxylic acid to form an adduct which is then esterified with an alcohol as above. The anthracene-acid adduct may be obtained by heating the two reactants together and esterified by heating with the alcohol, preferably in an inert solvent and optionally in the presence of an acid esterification catalyst, preferably in an amount of 0.1 to 1 per cent weight of reactants used.  Dibasic acids are preferred, e.g. maleic, itaconic and fumaric acids, other acids specified being crotonic, acrylic, methacrylic, angelic and cinnamic acids.  Alcohols may be primary, secondary or tertiary, e.g. trimethyl carbinol, isopropyl, ethyl, n-propyl, butyl, sec.-butyl, isobutyl, tert. amyl, hexyl, heptyl and octyl alcohols, pentanol-2 and -3, and methyl isopropyl carbinol and mixtures thereof.  Anthracene used need not be pure and commercial varieties containing, e.g. 30-40 per cent anthracene may be used. Inert solvents specified are xylene and anisole.  The esters are purified by molecular distillation. Anhydrides may be used instead of the acids.  In examples: (1) anthracene and diethyl maleate are heated for 5 hours at 100-170 DEG C. in the presence of 0.1 per cent of iodine and the diethyl ester is isolated with acetone; (2) anthracene and n-propyl maleate are similarly reacted to give the dipropyl ester; (3) crude anthracene maleic anhydride adduct and n-butanol are heated with p-toluene sulphuric acid for 6 hours at 115-135 DEG  C., water being removed by vacuum treatment, the dibutyl ester obtained being purified by refluxing with active charcoal in petroleum benzine and by treatment with caustic soda; (4) anthracene maleic acid adduct is similarly reacted with 2-ethyl hexanol and the di-(2-ethylhexyl) ester purified in a p  similar fashion; (5) relates to esters of trans endo 9, 10 adduct of anthracene and crotonic acid; (6) anthracene is refluxed with anisole at 155-160 DEG  C. for seven hours together with itaconic acid, iodine and hydroquinone to give the corresponding adduct esters of which are obtainable by conventional methods; (7) anthracene is refluxed with anisole for 9 hours at 150-153 DEG  C. together with fumaric acid and the endo 9, 10 adduct of anthracene and 1,2 ethylene dicarboxylic acid thus formed reacted with n-butanol to give the dibutyl ester thereof, and in (8) the above adduct is heated for 6 hours at 130-150 DEG  C. with n-octadecyl alcohol in the presence of p-toluene sulphonic acid, water being removed as in (3) and the di-n-octadecyl ester isolated and purified.  The Specification as open to inspection under Sect. 91 comprises also the subject-matter of Specification 647,518 and further refers to esters with all types of alcohols, i.e. whether saturated or unsaturated, e.g. methyl and benzyl alcohols are specified.  In an illustration dibenzyl maleate is reacted at 160-170 DEG  C. for 6 hours with pure anthracene in the presence of iodine and the dibenzyl ester adduct isolated.  This subject-matter does not appear in the Specification as accepted.