Organic compounds -- part of the class 532-570 series – Organic compounds – Diazo or diazonium
Reexamination Certificate
1999-08-10
2001-07-24
Stockton, Laura L. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Diazo or diazonium
C548S186000, C548S193000, C548S203000
Reexamination Certificate
active
06265553
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to intermediate thiazole compounds and a process for preparing 2-chloro-5-chloromethyl-thiazole which is a known compound useful for the preparation of insecticides.
BACKGROUND OF THE INVENTION
The compound 2-chloro-5-chloromethyl-thiazole is known intermediate useful for the preparation of insecticides. See European patent application No. 192,060. U.S. Pat. No. 4,748,243 to Beck et al. and EP 448,913 describe a process of preparing 2-chloro-5-chloromethyl-thiazole by reaction certain allyl isocyannates with chlorine.
SUMMARY OF THE INVENTION
Surprisingly, it has now been discovered that 2-chloro-5-chloromethylthiazole may be conveniently prepared from 2-chloro-5-hydroxymethylthiazole, 2-hydroxy-5-hydroxymethylthiazole or a 5-hydroxymethylthiazol-2-diazonium salt compound. These processes avoid the costs and hazards of using allyl isocyannate reagents and chlorine. Additionally, it has been discovered that 2-chloro-5-hydroxymethylthiazole and 2-hydroxy-5-hydroxymethylthiazole may be prepared via a 5-hydroxymethylthiazol-2-diazonium intermediate. Surprisingly, it has also been discovered that the 2-chloro-5-hydroxymethylthiazole, the 2-hydroxy-5-hydroxymethylthiazole or the 5-hydroxymethylthiazol-2-diazonium salts may be derived from 2-amino-5-hydroxymethylthiazole which is a known compound.
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of the invention is the compound 2-chloro-5-hydroxymethylthiazole having the formula:
(and acid addition salts thereof) which is useful for making 2-chloro-5-chloromethylthiazole a known intermediate which is ultimately useful for making known insecticides.
Another embodiment of the invention is the compound 2-hydroxy-5-hydroxymethylthiazole having the formula:
(and acid addition salts thereof) which is also useful for making 2-chloro-5-chloromethylthiazole.
It is recognized that salts 2-chloro-5-hydroxymethylthiazole and 2-hydroxy-5-hydroxymethylthiazole are also similarly useful intermediates and are part of the instantly disclosed invention. For example, the hydrochloride salts of 2-chloro-5-hydroxymethylthiazole and 2-hydroxy-5-hydroxymethylthiazole also are useful intermediates for preparing 2-chloro-5-chloromethylthiazole.
Another embodiment of the invention is 5-hydroxymethylthiazolyl-2-diazonium salt of formula (1):
(and acid addition salts thereof) wherein A
−
is a counter-anion derived from an acid HA, wherein HA is an organic acid or inorganic mineral acid. The organic acid for example may be formic acid, acetic acid, or benzoic acid. The inorganic acid for example may be a halogen acid, sulfuric acid, nitric acid, or phosphoric acid. Preferably A
−
is a halogen anion, an anion of the formula
−
OSO
2
R
1
wherein R
1
is C
1
-C
4
alkyl, phenyl, C
7
-C
10
alkylaryl, or C
5
-C
10
cycloalkyl; or an anion of the formula
−
OOC—R
2
wherein R
2
is C
1
-C
4
haloalkyl or R
1
. The diazonium salts are useful for making 2-chloro-5-hydroxymethylthiazole, 2-hydroxy-5-hydroxymethylthiazole and 2-chloro-5-chloromethylthiazole.
Another embodiment of the invention is the process for making 2-chloro-5-chloromethylthiazole (and acid addition salts thereof) comprising the step of reacting 2-chloro-5-hydroxymethylthiazole, 2-hydroxy-5-hydroxymethylthiazole or a 5-hydroxymethylthiazolyl-2-diazonium salt with a chloride anion source in the presence of an acid. The chloride anion source is not limited to but may be selected from the group consisting of an inorganic acid, a chloride salt, an acyl chloride and a sulfonyl chloride. The inorganic acid acting as the chloride anion source for example may be HCl, SOCl
2
, PCl
3
, POCl
3
, or PCl
5
. The chloride salt may be for example NaCl, KCl , CaCl
2
, ammonium chloride or a mono-, di-, tri-, tetra-alkylammonium chloride. The acyl chloride for example may be acetyl chloride or benzoyl chloride; or for example a chloroformate or a thiochloroformate such as ethyl chloroformate or ethyl thiochloroformate. The sulfonyl chloride for example may be mesyl chloride or tosyl chloride. It will be recognized that when the starting reagent is a hydrochloride addition salt or is 5-hydroxymethylthiazolyl-2-diazonium chloride salt, the starting reagent itself will serve also as a chloride anion source.
The skilled artisan will realize that the presence of acid in the reaction medium may be generated in situ from the reaction of the appropriate chloride anion source with the 2-chloro-5-hydroxymethylthiazole, 2-hydroxy-5-hydroxymethylthiazole or any hydroxylic solvent that may be present in the reaction medium. The presence of acid in the reaction medium may also be provided by the addition of an organic acid or an inorganic acid. The organic acid for example may be formic acid, acetic acid, or benzoic acid. The inorganic acid for example may be a halogen acid, sulfuric acid, nitric acid, sulfur trioxide, phosphoric acid or phosphorous pentoxide.
The process may be conducted in the presence of a solvent. The solvent for example may be hexane, cyclohexane, chloroform, methylene chloride, diethyl ether, tetrahydrofuran, toluene, or water, or mixtures thereof. When water is present other by-products may result due to the hydrolysis. The process may also be advantageously conducted under reflux conditions.
Another embodiment of the invention is the process for making 2-chloro-5-hydroxymethylthiazole (and acid addition salts thereof) comprising the step of reacting 2-amino-5-hydroxymethylthiazole (and acid addition salts thereof) with an alkali metal nitrite in the presence of an acid and in the presence of a chloride anion source. The alkali metal nitrite may be either sodium nitrite or potassium nitrite. The presence of a chloride anion source may be obtained by addition of the chloride anion source described above. The presence of acid in the reaction medium may be achieved in a similar fashion as discussed above for preparing 2-chloro-5-chloromethylthiazole. Thus it will be recognized that under the appropriate reaction conditions (e.g. temperature, pressure, concentration, reaction time etc.), 2-chloro-5-chloromethylthiazole may be prepared directly from 2-amino-5-hydroxymethylthiazole without isolating or purifying the intermediate 2-chloro-5-hydroxymethylthiazole.
Another embodiment of the invention is the process for making 2-chloro-5-hydroxymethylthiazole (and acid addition salts thereof) comprising the step of reacting a 5-hydroxymethylthiazolyl-2-diazonium salt with a chloride anion source in the presence of an acid. The reaction conditions regarding the chloride anion source and the presence of acid are the same or similar to those used for the preparation of 2-chloro-5-chloromethylthiazole discussed above. It will be recognized that when the 5-hydroxymethylthiazolyl-2-diazonium chloride salt (or hydrochloride salt thereof) is used it will serve also as a chloride anion source.
Another embodiment of the invention is the process for making 2-hydroxy-5-hydroxymethylthiazole (and acid addition salts thereof) comprising the step of reacting 2-amino-5-hydroxymethylthiazole (and acid addition salts thereof) with an alkali metal nitrite in the presence of water. The alkali metal nitrite may be either sodium nitrite or potassium nitrite. The presence of a water may be obtained by addition of water or the water may be carried into the reaction from the previous reaction step(s) for preparing the 2-amino-5-hydroxymethylthiazole. Thus it will be recognized that the further addition of a chloride anion source in the presence of acid may be used to prepare 2-chloro-5-chloromethylthiazole directly from 2-amino-5-hydroxymethylthiazole without isolating or purifying the intermediate 2-hydroxy-5-hydroxymethylthiazole.
Another embodiment of the invention is the process for making 2-hydroxy-5-hydroxymethylthiazole (and acid addition salts thereof) comprising the step of reacting a 5-hydroxymethylthiazolyl-2-diazonium salt with water.
Another embodiment of the invention is the process for making the 5-hydroxymethylthiazolyl-2-diazonium salt of
Stockton Laura L.
Syngenta Crop Protection Inc.
Teoli, Jr. Wiliam A.
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