Organic compounds -- part of the class 532-570 series – Organic compounds – Thiocyanate esters
Reexamination Certificate
2000-04-07
2001-04-24
Gerstl, Robert (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Thiocyanate esters
Reexamination Certificate
active
06222057
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for the preparation of 2-chloro-5-chloromethyl-1,3-thiazole. 2-Chloro-5-chloromethyl-1,3-thiazole prepared according to the present invention is useful as a synthesis intermediate for agricultural chemicals, for example, as a synthesis intermediate for hexahydrotriazine compounds useful as insecticides (refer to Japanese Patent Publication No. HEI 6-776).
2. Discussion of the Background
As a preparation process of 2-chloro-5-chloromethyl-1,3-thiazole, known are (1) a process of reacting allyl isothiocyanate with chlorine (refer to Japanese Patent Application Laid-Open No. SHO 63-83079) and (2) a process of reacting 2-chloroallyl isothiocyanate with a chlorinating agent (refer to Japanese Patent Application Laid-Open No. HEI 4-234864).
The reaction described in the above process (1) is however a markedly severe reaction which requires a large excess amount of a chlorinating agent and high temperature and in addition, plural byproducts are formed together with the target product 2-chloro-5-chloromethyl-1,3-thiazole so that this process is accompanied by the problem that 2-chloro-5-chloromethyl-1,3-thiazole so obtained has low purity. On the other hand, the process described in the above (2) is also accompanied with the problem that 2-chloroallyl isothiocyanate, which is a starting material, is not available at low cost. Accordingly, it is difficult to say that each of these processes is an industrially excellent process for the preparation of 2-chloro-5-chloromethyl-1,3-thiazole.
In addition, a process of heating 3-chloro-1-thiocyanato-2-propene in dioxane is known as a process for the preparation of 3-chloro-1-isothiocyanato-1-propene (refer to Journal f. prakt. Chemie. 322(4), 629(1980)).
It is however known that the above process has a low yield (refer to Comparative Example 2 which will be described below) and dioxane which is used as a solvent is carcinogenic. Accordingly, it is difficult to say that this process is industrially advantageous for the preparation of 3-chloro-1-isothiocyanato-1-propene.
Furthermore, as a process for the preparation of 3-chloro-1-thiocyanato-2-propene, a process of reacting 1,3-dichloropropene and potassium thiocyanate in dimethyl sulfoxide is shown (refer to Journal f. prakt. Chemie. 322(4), 629(1980)).
The above process however has a yield as low as 47% so that it is difficult to say that it is an industrially advantageous process for the preparation of 3-chloro-1-thiocyanato-2-propene.
With respect to the processes described in the above (1) and (2), isolation and purification of 2-chloro-5-chloromethyl-1,3-thiazole are carried out by distillation.
Since 2-chloro-5-chloromethyl-1,3-thiazole has low thermal stability and its reflux ratio cannot be increased, 2-chloro-5-chloromethyl-1,3-thiazole purified by distillation has a low purity. It is difficult to say that distillation is an excellent purification method for 2-chloro-5-chloromethyl-1,3-thiazole. Accordingly, there is a demand for a purification method to obtain 2-chloro-5-chloromethyl-1,3-thiazole having a higher purity.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an industrially advantageous process for preparing 2-chloro-5-chloromethyl-1,3-thiazole under mild conditions using an easily available and inexpensive starting material without using a large excess amount of a chlorinating agent.
Another object of the present invention is to provide an industrially advantageous process for the preparation of 3-chloro-1-isothiocyanato-1-propene in high purity and in high yield.
A further object of the present invention is to provide an industrially advantageous process for the preparation of 3-chloro-1-thiocyanato-2-propene in high purity and in high yield.
A still further object of the present invention is to provide a process for the purification of 2-chloro-5-chloromethyl-1,3-thiazole with good purity.
In a first aspect of the present invention, there is thus provided a process for the preparation of 2-chloro-5-chloromethyl-1,3-thiazole, which comprises reacting 3-chloro-1-isothiocyanato-1-propene with a chlorinating agent.
In a second aspect of the present invention, there is also provided a process for the preparation of 2-chloro-5-chloromethyl-1,3-thiazole, which comprises rearranging 3-chloro-1-thiocyanato-2-propene in the presence of a salt of one or more than one metal selected from the group consisting of metals belonging to Group 2A, Group 7A, Group 8 and Group 1B of the long-form periodic table to obtain 3-chloro-1-isothiocyanato-1-propene; and reacting the 3-chloro-1-isothiocyanato-1-propene with a chlorinating agent.
In a third aspect of the present invention, there is also provided a process for the preparation of 3-chloro-1-isothiocyanato-1-propene, which comprises rearranging 3-chloro-1-thiocyanato-2-propene in the presence of a salt of one or more than one metal selected from the group consisting of metals belonging to Group 2A, Group 7A, Group 8 and Group 1B of the long-form periodic table.
In a fourth aspect of the present invention, there is also provided a process for the preparation of 2-chloro-5-chloromethyl-1,3-thiazole, which comprises reacting 1,3-dichloropropene and a thiocyanate salt
(a) in the presence of water,
(b) in the presence of an organic solvent which is water-soluble and has a boiling point of 150° C. or lower, or
(c) in an organic solvent in the presence of a phase transfer catalyst, to obtain 3-chloro-1-thiocyanato-2-propene;
rearranging the 3-chloro-1-thiocyanato-2-propene in the presence of a salt of one or more than one metal selected from the group consisting of metals belonging to Group 2A, Group 7A, Group 8 and Group 1B of the long-form periodic table to obtain 3-chloro-1-isothiocyanato-1-propene; and reacting the 3-chloro-1-isothiocyanato-1-propene with a chlorinating agent.
In a fifth aspect of the present invention, there is also provided a process for the preparation of 3-chloro-1-isothiocyanato-1-propene, which comprises reacting 1,3-dichloropropene and a thiocyanate salt
(a) in the presence of water,
(b) in the presence of an organic solvent which is water-soluble and has a boiling point of 150° C. or lower, or
(c) in an organic solvent in the presence of a phase transfer catalyst, to obtain 3-chloro-1-thiocyanato-2-propene;
and rearranging the 3-chloro-1-thiocyanato-2-propene in the presence of a salt of one or more than one metal selected from the group consisting of metals belonging to Group 2A, Group 7A, Group 8 and Group 1B of the long-form periodic table.
In a sixth aspect of the present invention, there is also provided a process for the preparation of 3-chloro-1-thiocyanato-2-propene, which comprises reacting 1,3-dichloropropene and a thiocyanate salt
(a) in the presence of water,
(b) in the presence of an organic solvent which is water-soluble and has a boiling point of 150° C. or lower, or
(c) in an organic solvent in the presence of a phase transfer catalyst.
In a seventh aspect of the present invention, there is also provided a process for the purification of 2-chloro-5-chloromethyl-1,3-thiazole, which comprises recrystallizing crude 2-chloro-5-chloromethyl-1,3-thiazole using one or more than one organic solvent selected from the group consisting of hydrocarbons, ethers, aldehydes, ketones, esters and alcohols.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Each of the preparation processes of the present invention will hereinafter be described specifically.
Process 1
A process to obtain 3-chloro-1-thiocyanato-2-propene by reacting 1,3-dichloropropene and a thiocyanate salt
(a) in the presence of water,
(b) in the presence of an organic solvent which is water-soluble and has a boiling point of 150° C. or lower, or
(c) in an organic solvent in the presence of a phase transfer catalyst:
Examples of the thiocyanate salts include alkali metal salts such as sodium thiocyanate and potassium thiocyanate; alkaline earth metal salts such as calcium thiocyanate and magnesium thiocyanate; and ammonium thiocyanate. Am
Asanuma Goro
Matsuda Hideki
Shiono Manzo
Gerstl Robert
Kuraray Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Process for the preparation of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the preparation of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2480830