CN1098833C

CN1098833C - Process for preparing orthoformate

Info

Publication number: CN1098833C
Application number: CN00104440A
Authority: CN
Inventors: 杨丰科
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-06-27
Filing date: 2000-06-27
Publication date: 2003-01-15
Anticipated expiration: 2020-06-27
Also published as: CN1276366A

Abstract

The present invention relates to a method for preparing orthoformate. For improving the yield of orthoformate, the present invention is favorable to control reaction and is suitable for industrialization production. The present invention is characterized in that one of catalysts (namely FeSO4, NiSO4, CoSO4, CuSO4, Cu(NO3)2, CoCl2, SnCL2, CuI and CuBr) and CuCl, the amount is 3.0/1000 to 10.0/1000 of that of chloroform measured by weight, reaction is carried out in a closed system, phenol antioxidants are added, and chloroform and sodium alcoholate are added in a reactor at the same speed according to the quality molar ratio of 1:3. The yield of orthoformate in industrial production can be obviously improved by the present invention, and reaction can be controlled easily.

Description

Preparation method of orthoformate

The invention relates to a preparation method of orthoformate.

Esterification of sodium alkoxide and chloroform gives the orthoformate. The reaction equation is as follows:

in the formula: r is ethyl, and the product is triethyl orthoformate; r is methyl, and the product is trimethyl orthoformate. The preparation of trimethyl orthoformate and triethyl orthoformate has been reported in many patents. Japanese laid-open patent publication No. 83.185.537 (CAl01.22982), 84.01435(CA 100: 209184) and Chinese patent application No. 92107627.4 (CN 1068103) describe reactions of quaternary systems, i.e., the corresponding alcohols, chloroform, NaOH, H₂And O, reacting together, wherein the core is still NaOH and alcohol to generate sodium alkoxide, and then the sodium alkoxide and chloroform react to generate trimethyl orthoformate and triethyl orthoformate, and the trimethyl orthoformate and the triethyl orthoformate are unstable in water and are easy to generate hydrolysis reaction. As long as the reaction system contains water, the yield of orthoformate is not high, and moreover, the amount of organic solvent in such a reaction system is large, and the waste in the post-treatment process is large. The former soviet patent also reports the preparation of this class of materials (CA 119: 180391), and the preparation process of this patent also uses a phase transfer catalyst, which is too expensive to be suitable for production. Still other patents report alternative preparation methods (CA 116: 2l3995), which are not suitable for industrial production due to the expensive reagents used. German patent reports (DE 3,606,472; CA 107: 153942) the direct reaction of sodium alcoholates with chloroform. The preparation process adopts chloroform to drop into sodium alkoxide solution, and the feeding method has some defects. First, the chloroform and sodium alkoxide reaction is a strongly exothermic reaction. The reaction speed is fast, and the CHCl is added in a feeding mode₃In the high concentration of sodium alkoxide in the reaction, the reaction is too violent, which is not favorable for controlling the reaction. Second, sodium methoxide is both a strong nucleophile and a strong base reagent, while CHCl₃α elimination is readily observed by strong alkali at high concentrations (Jack, Hine, J. Amer. chem. soc.1950, 2438; organic chemistry, volume 14, P12).

The invention aims to provide a preparation method of orthoformate, which can improve the yield of orthoformate, is beneficial to controlling the reaction process and is suitable for industrial production.

The purpose of the invention is realized as follows: a method for preparing orthoformate has the reaction formula: in the formula: r is ethyl, and the product is triethyl orthoformate; r is methyl, the product is trimethyl orthoformate, a catalyst is used in the esterification process, and the catalyst is as follows: FeSO₄、NiSO₄、CoSO₄、CuSO₄、Cu(NO₃)₂、CoCl₂、SnCL₂One of CuI, CuBr and CuCl, the dosage of which is 3.0 per mill-10.0 per mill of chloroform according to weight, the reaction is carried out in a closed system, and a phenol antioxidant is added, chloroform and sodium alkoxide are added into a reactor at the same speed according to the mass molar ratio of 1: 3. The phenol antioxidant is one of phenol, cresol, p-tert-butylphenol, 2, 4-di-tert-butylphenol, 2, 6-di-tert-butyl-4-cresol and hydroquinone.

The invention has the advantages that: becausethe esterification catalyst FeSO is adopted₄、NiSO₄、CoSO₄、CuSO₄、Cu(NO₃)₂、CoCl₂、SnCL₂The catalytic action process of one of CuI, CuBr and CuCl and the metal ions have empty orbitals which can receive electrons provided by chlorine atoms to enable the metal ions to have partial complexing bonding property, so that the C-CL fracture in chloroform is influenced. In addition, the oxygen anions in the sodium alcoholate also act as complexing or complexing agents for these heavy metalsPartial complexation changes the property of oxygen anions in alcohol, thus reducing the alkalinity of sodium alkoxide, enhancing the nucleophilicity and improving the selectivity of sodium alkoxide. This results in a substantial increase in the esterification yield. In the preparation process, a closed system and a phenol antioxidant are also adopted, and the phenol antioxidant is generally various substituted phenols. One of phenol, cresol, p-tert-butylphenol, 2, 4-di-tert-butylphenol, 2, 6-di-tert-butylphenol-4-cresol and hydroquinone.

In the preparation process, chloroform is dripped into the sodium alkoxide solution, and the reaction is very violent and is not easy to control. The addition of sodium alkoxide to chloroform slowed the reaction slightly, but was still poorly controlled. The reason is that under the reaction conditions, one reactant is excessive, the reaction is carried out at high concentration, and the two feeding modes have influence on the product yield, particularly in the preparation process of triethyl orthoformate, the product yield is 68% by dropwise adding sodium alkoxide to chloroform and is obviously higher than the product yield of 60% by dropwise adding chloroform to sodium alkoxide. In the preparation process, chloroform and sodium alkoxide are simultaneously added into the reaction dropwise, so that the two substances react under the condition of low concentration, the reaction is slow in heat release and average in heat release, the solvent effect in the system is constant, the reaction selectivity is improved, and the whole reaction is stable and easy to operate and control.

After a closed system is adopted, the pressure in the reaction system is in a variation range of 0-0.2MPa and is closely related to the feeding speed. The pressure has positive influence on the reaction, the pressure can promote the reaction to be complete, and the reaction time is reduced, and the pressure is generally 0.05-0.2 MPa. The yield of trimethyl orthoformate is only 78% under normal pressure, and 80-85% under closed system and pressure. Pressure exists, and the heat preservation time is short after the feeding is finished. No pressure exists, and the heat preservation time is long after the feeding is finished. Chloroform and sodium alcoholate in a closed system are simultaneously added, and catalyst and antioxidant are added, so that the yield of trimethyl orthoformate is up to 96%, and the yield of triethyl orthoformate is up to 76%.

The product purification adopts common fractionation and rectification, and can meet the quality requirement.

The present invention will be further described with reference to the following examples.

In the preparation of orthoformate from sodium alcoholate and chloroform, FeSO is used₄The catalyst is 3 per mill of chloroform, the reaction is carried out in a closed system, and the phenol antioxidant is added, and the chloroform and the sodium alkoxide are added into the reactor at the same speed according to the mass molar ratio of 1: 3.

In the above examples, the catalyst FeSO₄The amount of the chloroform-based solvent is 7.5 per mill of the chloroform, and the rest is the same as above

Examples are given.

In the above examples, the catalyst FeSO₄The amount of chloroform was 10% by weight, as in the previous examples.

In the above examples, NiSO was used₄、CoSO₄、CuSO₄、Cu(NO₃)₂、CoCl₂、SnCL₂FeSO substituted by one of CuI, CuBr and CuCl₄As a catalyst, the other examples are the same as above.

In the above examples, the phenol antioxidant was replaced with one of cresol, p-tert-butylphenol, 2, 4-di-tert-butylphenol, 2, 6-di-tert-butylphenol-4-cresol and hydroquinone, and the other examples are the same as those described above.

Claims

1. A method for preparing orthoformate has the reaction formula: in the formula: r is ethyl, and the product is triethyl orthoformate; r is methyl, and the product is trimethyl orthoformate, and is characterized in that: in the esterification process, a catalyst FeSO is used₄、NiSO₄、CoSO₄、CuSO₄、Cu(NO₃)₂、CoCl₂、SnCL₂One of CuI, CuBr and CuCl, the dosage of which is 3.0 per mill-10.0 per mill of chloroform according to weight, the reaction is carried out in a closed system, and a phenol antioxidant is added, chloroform and sodium alkoxide are added into a reactor at the same speed according to the mass molar ratio of 1: 3.

2. The method according to claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the phenol antioxidant is one of phenol, cresol, p-tert-butylphenol, 2, 4-di-tert-butylphenol, 2, 6-di-tert-butyl-4-cresol and hydroquinone.