Patent GB-788887-A (GB)
Title: Improvements in or relating to the production of glycidyl ethers of polyhydric phenols
Filed: 1956-01-30
Abstract: In the production of glycidyl ethers of di-, or polyhydric phenols, which on further reaction with additional phenol are converted to epoxy resins, the di-, or polyhydric phenol is reacted with at least 1.5 mols. epihalohydrin per phenolic hydroxyl equivalent in the presence of at least 90-98 per cent of the alkali metal hydroxide per phenolic hydroxyl equivalent, after which the unreacted epihalohydrin is separated from the reaction mixture and the polyglycidyl ether is contacted with additional alkali metal hydroxide in excess of that required to remove the halogen in the glycidyl ethers.  Preferably 3-6 mols. epichlorhydrin are reacted per phenolic hydroxyl group. Water formed during the reaction is azeotropically distilled off with the epichlorhydrin, the distilled vapours are condensed, the condensate separated into aqueous and epichlorhydrin layers which latter is recycled to the reaction mixture; flash distillation followed by vacuum distillation may be employed.  The glycidyl ether may be purified by adding a solvent, e.g. ketones and aromatic hydrocarbons and water, and separating the brine layer from the solution of the ether in the solvent.  A table shows that the further reaction of the ether and a dihydric phenol is affected by the amount of halogen in the ether, the conversion being reduced from 100 per cent at up to 3 per cent chlorine content to 84 per cent with 2.7 per cent Cl content.  A table also shows that when the amount of NaOH present is reduced below 90 per cent, the percentage of molecules containing phenolic groups increases rapidly, while if the percentage is increased above 98 per cent the percentage of epichlorhydrin polymers produced increases.  Suitable polyhydric phenols for the reaction are resorcinol, phloroglucinol, 1,5 - dihydroxy naphthalene. bis-phenol, novolac resin obtained by acid condensation of phenol or cresol with aldehydes; condensates of phenol with cardanol aliphatic diols or unsaturated fatty oil.  The epichlorhydrin acts as a solvent as well as a reactant and suppresses the formation of gelled products with dihydroic phenols.  The process may be effected in batch or continuous operation.  Epichlorhydrin and bis-phenol in mol. ratio 10/1 were heated to 100 DEG  C. in a flask provided with distilling head and separator and 1.90 mols. NaOH added as a 40 per cent aqueous solution; water and epichlorhydrin distilled off to maintain the water in the reaction mixture at about 1.5 per cent; unreacted epichlorhydrin was flashed off and vacuum distilled; the residue was cooled, mixed with an equal weight of isobutyl ketone and 3 times as much water, the brine phase was separated and the organic phase containing 1 per cent chlorine was further reacted with an equal weight of 5 per cent NaOH solution at 80 DEG  C.; the brine phase was separated and the product treated with sodium dihydrogen phosphate. The resulting ether was found to contain 0.25 per cent Cl.  It had an epoxy equivalent of 0.521 and a molecular weight 355.  When heated with 35.6 per cent by weight of bisphenol a 100 per cent conversion was obtained.  U.S.A. Specification 2,467,171 is referred to.ALSO:In the production of glycidyl ethers of dihydric phenols which on further reaction with additional phenol are converted to epoxy resins, the dihydric phenol is reacted with at least 1.5 mols. epihalohydrin per phenolic hydroxyl equivalent in the presence of at least 90-98 per cent of the equivalent of alkali metal hydroxide per phenolic hydroxyl equivalent, after which the unreacted epihalohydrin is separated from the reaction mixture and the polyglycidyl ether is contacted with additional alkali metal hydroxide in excess of that required to remove the halogen therein.  Preferably 3-6 mols. epichlorhydrin are reacted per phenolic hydroxyl group.  Water formed during the reaction is azeotropically distilled off with the epichlorhydrin, the distilled vapours are condensed, and the condensate separated into aqueous and epichlorhydrin layers which latter is recycled to the reaction mixture; flash distillation followed by vacuum distillation may be employed.  The glycidyl ether may be purified by adding a solvent, e.g. ketones and aromatic hydrocarbons and water and separating the brine layer from the solution of the ether in the solvent.  A table shows that the further reaction of the ether and a dihydric phenol is affected by the amount of halogen in the ether, the conversion being reduced from 100 per cent at up to 3 per cent chlorine content to 84 per cent with 2.7 per cent Cl content.  A table also shows that when the amount of NaOH present is reduced below 90 per cent, the percentage of molecules containing phenolic groups increases rapidly while if the percentage is increased above 98 per cent the percentage of epichlorhydrin polymers produced increases.  Suitable polyhydric phenols for the reaction are resorcinol, phloroglucinol 1,5-dihydroxy naphthalane bis-phenol, novolac resins obtained by acid condensation of phenol, cresol, &c., with aldehydes; condensates of phenol with cardanol, aliphatic diols or unsaturated fatty oils.  The epichlorhydrin acts as a solvent as well as a reactant and suppresses the formation of gelled products with dihydric phenols.  The process may be effected in batch or continuous operation.  Epichlorhydrin and bis-phenol in mol ratio 10/1 were heated to 100 DEG  C. in a flask provided with distilling head and separator and 1.90 mols. NaOH added as a 40 per cent aqueous solution; water and epichlorhydrin were distilled off to maintain the water in the reaction mixture at about 1.5 per cent; unreacted epichlorhydrin was flashed off and vacuum distilled; the residue was cooled, mixed with an equal weight of isobutyl ketone and 3 times as much water, the brine phase was separated and the organic phase containing 1 per cent chlorine was further reacted with an equal weight of 5 per cent NaOH solution at 80 DEG  C.; the brine phase was separated and the product treated with sodium dihydrogen phosphate; the resulting ether was found to contain 0.25 per cent Cl, had an epoxy equivalent of 0.521 and a molecular weight of 355.  When heated with 35.6 per cent by weight of bis-phenol a 100 per cent conversion was obtained.  U.S.A. Specification 2,467,171 is referred to.