Preparation and thermal curing of single-ring bis(cyanate) ester monomers

Patent metadata

Field	Value
Publication number	US-9434685-B1
Application number	US-201615059463-A
Country	US
Kind code	B1
Filing date	Mar 3, 2016
Priority date	Nov 21, 2011
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

A class of modified single-ring cyanate esters which have shown the ability to tailor and control the glass-transition (Tg) of the cured resins as well as the water uptake.

First claim

What is claimed is:

1. A method for preparing 3,5-bis(cyanato)benzoate esters, comprising:
reacting 3,5-di(benzyloxy)benzoic acid with oxalyl chloride;
treating said acid/chloride with an aliphatic and/or aromatic alcohol (ROH), wherein R is an aliphatic and/or aromatic component of said aliphatic and/or aromatic alcohol, in the presence of a base to form (V):

dissolving said (V) in at least one solvent, adding a solid catalyst and hydrogen gas, and reacting by stirring for about 2 to about 48 hours;
removing of said catalyst by filtration and solvents by evaporation forming 3,5-dihydroxybenzoate ester (I);
purifying said 3,5-dihydroxybenzoate ester (I);
treating said 3,5-dihydroxybenzoate ester (I) with cyanogen halide in the presence of at least one base and at least one solvent forming 3,5-bis(cyanato)benzoate ester (II);
isolating said 3,5-bis(cyanato)benzoate ester (II): and
purifying said 3,5-bis(cyanato)benzoate ester (II) to attain a cyanate ester monomer capable of forming thermally cured resins.

2. The method according to claim 1 , wherein said base is selected from an aliphatic amine including from about 3 to about 18 carbons.

3. The method according to claim 1 , wherein said base is an amine supported on cross-linked polymeric support.

4. The method according to claim 1 , wherein said oxalyl chloride is used as 1.0 to 1.5 mol-equivalent to said 3,5-di(benzyloxy)benzoic acid.

5. The method according to claim 1 , wherein said hydrogenation catalyst uses at least one metal selected from palladium and platinum.

6. The method according to claim 5 , wherein said palladium is supported on a carbon.

7. The method according to claim 5 , wherein said platinum oxide is the catalyst used in 0.01 to 2 wt-% of said 3,5-di(benzyloxy)benzoate ester (V).

Assignees

• Us Navy

Inventors

• Wright Michael E

Classifications

• C07C253/04 Primary

  by reaction of cyanogen halides, e.g. ClCN, with organic compounds · CPC title

• C07C67/10

  by reacting carboxylic acids or symmetrical anhydrides with ester groups or with a carbon-halogen bond (preparation from carboxylic acid halides C07C67/14) · CPC title

• C07C261/02 Primary

  Cyanates · CPC title

• C07C231/02

  from carboxylic acids or from esters, anhydrides, or halides thereof by reaction with ammonia or amines · CPC title