Aryl ether oligomers and process for making aryl ether oligomers
View Patent ↗An aryl composition includes aryl ether oligomers. These compositions may be prepared by reaction of one or more dihalobenzenes with one or more dihydroxybenzenes by an Ullman ether reaction. The oligomers may have two or more benzene rings and include terminal halogen, e.g., bromine (Br), or hydroxyl (OH) groups. These oligomers may be brominated to form flame retardant compositions for thermoplastic polymers.
1. A method for preparing aryl ether oligomers, said method comprising reacting dihalobenzene with a salt of dihydroxybenzene,
wherein the number of moles of dihalobenzene exceeds the number of moles of the salt of dihydroxybenzene; and
wherein the ratio of the number of moles of dihalobenzene to the number of moles of the salt of dihydroxybenzene is from about 1.1:1 to about 1.9:1.
2. The method of claim 1 further comprising removing aryl compounds with one or two benzene rings from the reaction product produced by reacting dihalobenzene with a salt of dihydroxybenzene.
3. The method of claim 1 , wherein dihalobenzene is reacted with the potassium salt of resorcinol.
4. The method of claim 3 , wherein said dihalobenzene is 1,4-dibromobenzene and 1,4-dibromobenzene is reacted with the potassium salt of resorcinol in the presence of a copper containing catalyst.
5. The method of claim 4 , wherein said copper containing catalyst is selected from the group consisting of cupric oxide and cupric salt.
6. The method of claim 5 , wherein said cupric salt is cupric acetate.
7. The method of claim 3 , wherein said potassium salt of resorcinol is prepared by the steps of:
(a) preparing a reaction mixture by combining said 1,4-dibromobenzene, said resorcinol, an aqueous solution KOH, and a solvent; and
(b) heating the reaction mixture of step (a) to reflux to remove water.
8. The method of claim 7 , wherein the molar ratio of said 1,4 -dibromobenzene to said resorcinol in step (a) is from about 1.1:1 to about 1.6:1; and
wherein the molar ratio of KOH to resorcinol is from about 1.8:1 to about 2.5:1.
9. The method according to claim 8 , wherein the molar ratio of KOH to resorcinol is from about 2.1:1 to about 2.5:1.
10. The method of claim 9 , further comprising the steps of:
(c) removing KBr salts from the product mixture of step (b) by filtration;
(d) stripping the solvent from the product mixture of step (c) to form an organic residue;
(e) washing the organic residue of step (d) with a dilute aqueous solution of a base followed by water washing; and
(f) removing residual 1,4-dibromobenzene from the washed organic residue of step (e) by distillation.
11. The method of claim 10 , wherein a ligand is added with said copper containing catalyst to the reaction mixture of step (c).
12. The method of claim 11 , wherein said ligand is selected from the group consisting of 1,10-phenanthroline, dimethylglycine, 1-butylimidazole, 1-methylimidazole and DL-alanine.
13. The method of claim 11 , wherein the molar ratio of copper containing catalyst to resorcinol is from about 0.01:1 to about 0.04:1 and
wherein the molar ratio of copper containing catalyst to ligand is from about 1:3 to about 3:1.