Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1997-10-16
1998-10-13
Barts, Samuel
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
562606, C07C 6934
Patent
active
058213821
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for manufacturing thiol compounds by causing reaction between (1) unsaturated compounds such as unsaturated esters or unsaturated acids and (2) hydrogen sulfide.
The thiol compounds are chemical substance of great use which are widely utilized as material of pharmaceutical products, agricultural chemicals, and various kinds of industrial chemical products.
BACKGROUND ART
The following methods have been known as methods for manufacturing 3-mercapto-propionic ester, which is one of thiol compounds, by causing reaction between, for example, (1) acrylic ester, which is one of unsaturated esters, and (2) hydrogen sulfide.
The Japanese Publication for Laid-Open Patent Application No. 62-63526/1987 (Tokukaisho 62-63526) discloses a method wherein magnesium oxide or an anionic exchange resin is used as catalyst in the system of reaction. However, this method requires, as conditions for the reaction, a reaction pressure of not lower than 13 atm, and large excess of hydrogen sulfide, for example, the molar ratio of 6:1 for hydrogen sulfide and acrylic ester. This leads to an excessive investment in plant and equipment, and therefore the foregoing method does not bring about satisfactory results from a viewpoint of industrial productivity.
The Japanese Examined Patent Publication No. 57-48155/1982 (Tokukosho 57-48155) discloses a method wherein 3-mercapto-propionic ester and/or thiodipropionic ester, which are reaction products, is/are used as solvent in the above system of reaction. By this method, 3-mercapto-propionic ester is obtained under a reaction pressure of about 10 atm at a relatively high yield. However, the foregoing method has a disadvantage in that excess of hydrogen sulfide with respect to acrylic ester should be increased in order to obtain 3-mercapto-propionic ester at a high selectivity and at a high yield.
Therefore, a method wherein polythiodipropionic ester such as dithiodipropionic ester is used as solvent in the aforementioned system of reaction, to raise the yield of 3-mercapto-propionic ester, is disclosed, for example, in the Japanese Examined Patent Publications No. 59-34181/1984 (Tokukosho 59-34181) and No. 63-19509/1988 (Tokukosho 63-19509), and the Japanese Publication for Laid-Open Patent Application No. 4-273851/1992 (Tokukaihei 4-273851). In addition, a method wherein sulfur is used is disclosed in the Japanese Examined Patent Publication No. 58-54138/1983 (Tokukosho 58-54138).
However, by none of the aforementioned methods, a satisfactory result can be obtained in respect of the lowering of the reaction pressure and the improvement of the yield. In other words, by none of the aforementioned methods, the reaction pressure can be satisfactorily lowered while the yield can be satisfactorily improved. Note that the Japanese Examined Patent Publication No. 63-35621/1988 (Tokukosho 63-35621) discloses a method wherein an amide compound having a specific structure is used as a solvent in the above system of reaction. Though by this method it is easy to recover the solvent after the reaction, the results obtained by this method are not satisfactory from a viewpoint of industrial productivity, since the yield of 3-mercapto-propionic ester is relatively low.
Therefore, a manufacturing method whereby the reaction pressure is further lowered and the selectivity and the yield are further improved is demanded, from a viewpoint of industrial productivity.
The present invention was made in light of the aforementioned problems of the conventional methods, and the object of the present invention is to provide a method whereby a thiol compound can be produced at a high selectivity and a high yield by smooth reaction between (1) an unsaturated compound such as an unsaturated ester or an unsaturated acid and (2) hydrogen sulfide.
DISCLOSURE OF THE INVENTION
A s a result of eager study by the inventors on a method for manufacturing thiol compounds, it was found that reaction between an unsaturated compound and hydrogen sulfide was smoothly c
REFERENCES:
patent: 5008432 (1991-04-01), Roberts
patent: 5157147 (1992-10-01), Chisholm et al.
Hino Youichi
Ishikawa Ryuichi
Wakao Norihiro
Barts Samuel
Nippon Shokubai Co. , Ltd.
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