Patent Application
20230257341
The present invention relates to a cis-para-substituted cyclohexylaminonitrile salt, a preparation method therefor, the use thereof as an intermediate for preparing a pesticide, and a method for preparing a pesticide by using the same as an intermediate.
Chinese patent CN103270020B discloses the cis-amino-4-alkoxy cyclohexane carbonitrile salt represented by the following formula,
wherein HX is hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, p-toluenesulfonic acid or methanesulfonic acid, and R1 is alkoxy.
However, the inventors of the present application found that the three inorganic acids of hydrochloric acid, sulfuric acid and phosphoric acid used in CN103270020B are not selective, and the cis-isomer compound cannot be selectively crystallized and separated by the salt formation of these acids with amino-4-alkoxycyclohexanecarbonitrile; the salt formed by acetic acid and the above cyclohexanecarbonitrile compound cannot be crystallized; the selectivity of p-toluenesulfonic acid and methanesulfonic acid is poor, which is not conducive to industrial production; the salt formed by formic acid and the above cyclohexanecarbonitrile compound is easy to agglomerate, has poor stability, and is easy to decompose, furthermore, the color of the salt becomes darker and the melting point thereof decreases during storage, which seriously affects the subsequent use of the product.
In Chinese patent CN110691771A, the above HX is changed into maleic acid and glycolic acid, and obtained good selectivity and product stability.
The inventors of the present application have found in practice that maleic acid and glycolic acid are difficult to be recycled and reused because they are easily soluble in water. Therefore, the inventors of the present application conducted further research on the selection and optimization of the above HX acid, and based on which the present invention was obtained.
One aspect of the present application relates to a cis-para-substituted cyclohexylaminonitrile salt represented by the following formula (I):
In the above formula (I), the para-substituent R is C1-10 alkyl or C1-10 alkyloxy, C2-10 alkenyl or C2-10 alkenyloxy, C2-10 alkynyl or C2-10 alkynyloxy, C3-10 cycloalkyl or C3-10 cycloalkyloxy, C3-10 heterocycloalkyl or C3-10 heterocycloalkyloxy containing 1-2 heteroatoms selected from O and N;
HX is benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid or salicylic acid.
Another aspect of the present application relates to a method of preparation for the cis-para-substituted cyclohexylaminonitrile salt of formula (I) above, which comprises adding benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid or salicylic acid into a solution of the cis trans para-substituted cyclohexylaminonitrile compound in an organic solvent, stirring and crystallizing, and then separating to obtain the compound of formula (I) in a solid form.
The present application also relates to the use of the cis-para-substituted cyclohexylaminonitrile salt of formula (I) as an intermediate for preparing a pesticide, such as spirotetramat.
The present application further relates to a method for preparing compound (II), in which the cis-para-substituted cyclohexylaminonitrile salt of formula (I) is used as a raw material, and the compound (II) is prepared by the following reaction:
In this application, unless otherwise specified, “%” means weight percentage.
In the above formula (I), R is C1-10 alkyl or C1-10 alkyloxy, C2-10 alkenyl or C2-10 alkenyloxy, C2-10 alkynyl or C2-10 alkynyloxy, C3-10 cycloalkyl or C3-10 cycloalkyloxy, C3-10 heterocycloalkyl or C3-10 heterocycloalkyloxy containing 1-2 heteroatoms selected from O and N, preferably C1-6 alkyl or C1-6 alkyloxy, C2-6 alkenyl or C2-6 alkenyloxy, C2-6 alkynyl or C2-6 alkynyloxy, C3-6 cycloalkyl or C3-6 cycloalkyloxy, C3-6 heterocycloalkyl or C3-6 heterocycloalkyloxy containing 1-2 heteroatoms selected from O and N, furthermore more preferably C1-6 alkyl or C1-6 alkyloxy, particularly preferably methyl or methoxy.
HX is benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid or salicylic acid, preferably benzoic acid or salicylic acid, particularly preferably benzoic acid.
Compared with maleic acid and glycolic acid, using the above acids as HX makes the salt forming by crystallization faster, and the crystallized product is loose and not easy to harden, with fast filtration and easy to rinse.
In addition, when the compound of formula (I) is used as an intermediate for subsequent reactions, HX will dissociate and return to a free acid, which needs to be recycled and reused as much as possible for environmental and raw material cost reasons. Maleic acid and glycolic acid are difficult to be recycled because of their good water solubility. Another advantage of using benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid and salicylic acid as HX is that these acids are slightly soluble or insoluble in water and precipitate in the aqueous phase after dissociation, and thus is easily recycled and reused.
Further, such as in the above reaction for preparation of formula (II) compound, an acid binding agent is required to neutralize the free HX. Another advantage of using benzoic, p-nitrobenzoic, m-nitrobenzoic, p-toluic and salicylic acids as HX is that these acids are monoacids, which allows to reduce the amount of acid binding agent compared to the dibasic maleic acid.
By reacting cis trans mixture of the para-substituted cyclohexylaminonitrile compound with benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid or salicylic acid to form salts, these acids preferentially react with the cis-isomer, and the obtained cis-isomer salts are insoluble in the solvent and precipitate as a solid, thereby selectively separating the cis-isomer as a solid salt.
The cis-isomer is the predominant isomer. Therefore, the higher the cis-isomer ratio and the lower the trans-isomer ratio in the solid precipitate, the better. Preferably, the ratio of cis trans in the solid precipitate is more than 90:10, more preferably 95:5 or more, and further preferably 96:4 or more.
On the other hand, the lower the cis: trans ratio in the filtrate, the better. Preferably, the ratio of cis: trans in the filtrate is less than 30:70.
A method of preparation for compound (I) of the present invention comprises the following steps: dissolving the cis trans para-substituted cyclohexylaminonitrile compound in an organic solvent, and then adding benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid or salicylic acid, stirring and crystallizing, separating the precipitated solid to obtain the compound of formula (I).
The cis trans para-substituted cyclohexylaminonitrile as the raw material compound used in the above preparation method of the present invention can be synthesized by, for example, the well-known Strecker reaction, or can also be synthesized by a known method disclosed in, for example, Chinese Patent Document CN103270020B.
The organic solvent includes but not limited to toluenes, ethers, alkanes or halogenated hydrocarbons, specific examples include but not limited to toluene, xylene, chlorobenzene, methyl tert-butyl ether, cyclohexane, methylcyclohexane, tetrahydrofuran, dichloromethane, tetrachloroethylene and the like. The solvent may be used alone or in combination of two or more.
The amount of the organic solvent used is preferably 1-10 times by mass, more preferably 2-5 times by mass, and further more preferably 3-4 times by mass, relative to the cis trans para-substituted cyclohexylaminonitrile compound.
When the amount of benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid or salicylic acid added is too small, the cis-isomer in cis trans raw material mixture cannot be fully reacted and separated, and when too much is added, more trans-isomer will be involved in the reaction. Therefore, the added amount of the above acid is preferably 0.8˜1.5 mole times, more preferably 1.0˜1.3 mole times the total amount of cis-isomer in the cis trans raw material mixture.
In the above preparation method of the present invention, stirring and crystallizing temperature is preferably 0˜40° C., more preferably 10˜30° C., particularly preferably 15˜20° C. The stirring and crystallizing time is preferably 2˜6 hours.
Preferably, ultrasonication is performed while stirring and crystallizing to accelerate crystallization and improve separation selectivity, especially when salicylic acid is used as the crystallizing acid.
The precipitated solid can be separated by filtration or other means. When benzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, p-toluic acid or salicylic acid is used, the obtained crystalline salt is loose, hard to harden and easy to filter.
The compound of formula (I) in the present invention is an important intermediate compound that can be used for the preparation of, for example, spirotetramat.
The compound of formula (I) in the present invention can react with acyl halide in the presence of acid binding agent, for example, reacts with 2,5-dimethylphenylacetyl chloride as follows to obtain compound (II):
In the above formula, HX and R are the same as defined above.
A salt of an alkali metal or alkaline earth metal or an organic amine and the like can be used as the acid binding agent. As specific examples, sodium hydroxide, sodium carbonate, sodium bicarbonate, triethylamine and the like can be listed.
The above reaction is preferably carried out in water and any organic solvent immiscible with water. The organic solvent is preferably one selected from toluene, xylene, dichloromethane, dichloroethane, tetrachloroethylene, ethyl acetate, isopropyl acetate, or a mixture thereof; The ratio of water to the organic solvent is preferably 1-5:5-1. The above reaction is preferably carried out at 0-30° C., more preferably at 0-15° C.
Took 300 g of xylene solution of a mixture of cis trans isomers of 4-methoxy-1-cyanocyclohexylamine (cis: trans=55: 45) containing 48 g of cis-isomer respectively, relative to the amount of cis-isomer in the mixture, added 1 mole equivalent of acid listed in Table 1 respectively, stirred and crystallized at room temperature, and the precipitated solid was filtered and rinsed with xylene. 2,5-dimethylphenylacetyl chloride and triethylamine were added to the filtrate, and the solid was dissolved in dichloromethane followed by an addition of 2,5-dimethylphenylacetyl chloride and triethylamine. Thus, the cyanamide compound in the filtrate and solid was amidated to produce the compound shown in formula (II), then detected by HPLC to determine cis trans ratio. The results are shown in Table 1.
A higher cis trans ratio in the obtained crystalline solid and a lower cis trans ratio in the filtrate implies a better selectivity of crystallization separation.
Mobile phase: methanol: water (adjusted to pH 2.5-2.7 by formic acid)=70:30
Chromatographic column: C18
Column temperature: 30° C.
Wavelength: 210 nm
Flow rate: 1.0 ml/min
Took 750 g of xylene solution of a mixture of cis trans isomers of 4-methoxy-1-cyanocyclohexylamine (cis: trans=55: 45) containing 105 g of cis-isomer, respectively, relative to the amount of cis-isomer in the mixture, added 1 mole equivalent of acid listed in Table 2 respectively, stirred and crystallized at 15˜20° C. Samples were taken separately at different time points, filtered, and the filtered solid was rinsed with xylene. Cis trans ratio of solid and filtrate was detected by HPLC in the same way as in Example 1. The results are shown in Table 2.
It can be seen from Table 2 that the crystallization speed can be accelerated by ultrasonic-assisted crystallization, and it helps to improve the separation selectivity.
The method of the present invention can separate cis trans-p-methoxy cyclohexylaminonitrile with good selectivity to obtain cis-para-substituted cyclohexylaminonitrile salt, which is an important intermediate for the synthesis of a pesticide such as spirotetramat.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202011138765.3 | Oct 2020 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2021/123804 | 10/14/2021 | WO |
