Sensitized production of sulfhydryl compounds using ultraviolet radiation
AssigneeHooker Chemicals & Plastics Corporation
InventorBobby F. Dannels
Life of this patent
Estimating the term…
Abstract
An improved process for production of sulfhydryl-terminated compounds by reaction of an allene compound and hydrogen sulfide is disclosed wherein the reaction is carried out in the presence of ultraviolet light of wavelength substantially above 2600 Angstroms and of an organic photosensitizing reagent to obtain a substantially colorless product of improved purity at an increased reaction rate. The invention also includes polymerization of the crude sulfhydryl-terminated product with an unsaturated compound to prepare sulfhydryl-terminated polythioethers which are useful as chemical intermediates and precursors of elastomeric sealants, such as architectural sealants.
Claims17
In a process for the production of a sulfhydryl-terminated polythioether which comprises the steps of
- 1. condensing an allene compound and hydrogen sulfide in liquid phase to produce a crude sulfhydryl-terminated hydrocarbon product,
- 2. polymerizing said crude sulfhydryl-terminated hydrocarbon product with an unsaturated hydrocarbon having at least one acetylenic bond or at least two ethylenic bonds to obtain the sulfhydryl-terminated polythioether,
- the improvement which comprises carrying out the step 1 reaction at a reaction temperature of about -100.degree. to about 90.degree. Centigrade, a reaction pressure of 0 to 3000 p.s.i.g. and a molar ratio of hydrogen sulfide to the allene compound of about 1:1 to about 20:1 in the presence of ultraviolet light of wavelength substantially above about 2600 Angstroms and a photosensitizing amount in the range of about 0.0005% to about 5% based on the weight of the reaction mixture of an organic photosensitizing reagent for said reaction to obtain a sulfhydryl-terminated thioether polymer substantially devoid of color.
In a process for the production of a sulfhydryl-terminated polythioether which comprises the steps of
- 1. condensing an allene compound and hydrogen sulfide in liquid phase to produce a crude sulfhydryl-terminated hydrocarbon product,
- 2. polymerizing said crude sulfhydryl-terminated hydrocarbon product with an unsaturated hydrocarbon having at least one acetylenic bond or at least two ethylenic bonds to obtain the sulfhydryl-terminated polythioether,
- the improvement which comprises carrying out steps 1 and 2 in the presence of a sensitizing amount in the range of about 0.0005% to about 5% based on the weight of the reaction mixture of an organic photosensitizing reagent for the reactions and of ultraviolet light of wavelength substantially above about 2600 Angstroms with the reaction temperature in step 1 being about -100.degree. to about 90.degree. Centigrade, the reaction pressure in step 1 being about 0 to about 3000 p.s.i.g., the molar ratio of hydrogen sulfide to the allene compound in step 1 being about 1:1 to about 20:1. The reaction temperature in step 2 being about -100.degree. to about 175.degree. Centigrade, the reaction pressure in step 2 being about 1 to about 10 atmospheres and the molar ratio of the unsaturated hydrocarbon reactant to the sulfhydryl-terminated hydrocarbon reactant in step 2 being about 0.7:1 to about 0.999:1, whereby the rates of the reactions of steps 1 and 2 are increased and substantially colorless product is obtained.
In the process for the formation of a sulfhydryl-terminated polythioether which comprises polymerizing an unsaturated hydrocarbon having at least one acetylenic bond or at least two ethylenic bonds with a sulfhydryl-terminated reactant selected from the group consisting of 1,3-propane dithiol, and substituted derivatives thereof, 1,2-propane dithiol and substituted derivatives thereof, and sulfhydryl terminated thioether oligomers of said propane dithiols and substituted propane dithiols said sulfhydryl-terminated reactant being prepared by reaction of an allene compound and hydrogen sulfide, the improvement which comprises carrying out the reaction in the presence of a sensitizing amount in the range of about 0.0005% to about 5% based on the weight of the reaction mixture of an organic photosensitizing reagent for the reaction and of ultraviolet light of wavelength substantially above about 2600 Angstroms at a reaction temperature of about -100.degree. to about 175.degree. Centigrade and a reaction pressure of about 1 to about 10 atmospheres and at a molar ratio of the unsaturated hydrocarbon reactant to the dithiol of about 0.7:1 to about 0.999:1 whereby the molecular weight of the product and the rate of the polymerization is increased and the purity of the product is enhanced.
Dependencies are inferred from the claim text.