Synthesis of diethynylbenzene
AssigneeHercules Incorporated
InventorsLawrence E. Carosino, David C. Herak
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Abstract
The invention provides an inexpensive synthesis process for preparation of diethynylbenzene monomers that are useful in the preparation of polyacetylenes. This process provides for the preparation of thermally sensitive monomers in a one-pot reaction using readily available materials at low temperatures in an environment capable of absorbing large amounts of energy. Divinylbenzene is first brominated and then dehydrobrominated with sodium hydroxide or potassium hydroxide preferably in the presence of a phase transfer agent followed by distillation to recover the diethylnylbenzene product.
Claims16
A process for making diethynylbenzene as a mixture of isomers which comprises:
- a. producing a brominated divinylbenzene product in a reaction mixture by in a gradual manner continuously and simultaneously combining mixed isomers of divinylbenzene with bromine in a sulfolane solvent wherein said divinylbenzene is present in a concentration not exceeding 5 percent by weight, wherein the temperature is between 0.degree.-50.degree. C., and wherein sufficient bromine is added to said reaction mixture to react with all olefinic unsaturation of said divinylbenzene;
- said bromine not to be more than 10 percent more than an amount necessary to react with all of said olefinic unsaturations and wherein the total amount of divinylbenzene added to the reaction mixture is between 20-50 percent by weight of the sulfolane solvent;
- b. reacting said brominated divinylbenzene product with a dehydrobromination caustic agent wherein an excess of said agent is added to total about 50-250 mole % more than the amount required to remove all organically bound bromine as a corresponding halide salt from said brominated divinylbenzene product, and wherein said caustic agent is added at a rate that maintains the temperature of the solution in the range of from about 20.degree.-50.degree. C. and continuing addition of said caustic agent until said excess of the agent is present and then completing said reaction with said caustic agent by heating a dehydrobrominated product to a temperature between about 90.degree. to about 100.degree. C. for a period of about 1/2 to 4 hours;
- c. removing said excess dehydrobromination caustic agent and said halide salts and isolating a layer comprising said sulfolane and diethynylbenzene;
- and
- d. recovering said diethynylbenzene from said isolated layer.
Dependencies are inferred from the claim text.