JPS63255247A - Production of malonic acid esters - Google Patents

Abstract

PURPOSE:To advantageously obtain the aimed compound in high purity and yield, by using a specific organotin compound as a catalyst in subjecting an alcohol and dimethyl malonate to ester interchange reaction to produce dialkyl malonates. CONSTITUTION:An alcohol and dimethyl malonate are subjected to ester interchange reaction to produce a dialkyl malonate. In the process, an organotin compound expressed by formula I or II (R1 and R2 are 1-8C, particularly 4C or 8C alkyl; R3-R6 are 4-8C, particularly 4C alkyl; R7 is 1-17C, particularly 7C, 11C or 17C alkyl) is used as a catalyst to afford the aimed compound in high yield and purity using the above-mentioned readily available and reusable catalyst without requiring a previous dehydration step, since the catalyst is not affected by a very small amount of moisture in the reaction system. Furthermore, the reaction time is short, since catalytic activity is not deteriorated during the reaction without causing side reaction and requiring a washing step.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing malonic acid dialkyl esters by transesterification, and particularly to a transesterification catalyst used therein.

[Prior Art] Sulfuric acid, alkali metal alkoxides, aluminum alkoxides, titanium alkoxides, and the like are known as transesterification catalysts.

[Problems to be Solved by the Invention] However, these catalysts had the following problems.

For example, if sulfuric acid is used as a catalyst and a secondary alcohol is used as a raw material, part of it will be dehydrated to produce olefins as a by-product, or if carried out industrially, it will corrode equipment.

When an alkali metal alkoxide is used as a catalyst, the catalytic activity gradually decreases during the reaction and it must be added repeatedly, and it is necessary to remove trace amounts of water from the raw material before adding the catalyst. However, there were problems such as the impossibility of reusing the catalyst and the necessity of a washing process.

Additionally, when aluminum alkoxide or titanium alkoxide is used as a catalyst, the reaction time is longer due to low catalytic activity, trace amounts of water in the raw materials must be removed in advance, and a cleaning process is required. There were other problems.

The present invention aims to solve the above problems. That is, when producing malonic acid dialkyl ester from malonic acid dimethyl ester by transesterification reaction,
As a catalyst, it is not affected by trace amounts of moisture in the reaction system, does not reduce catalytic activity, does not cause side reactions, does not require a washing process, and uses a material that can be reused as a catalyst to achieve high yields. The purpose is to produce a target product of purity.

[Means and effects for solving the problems] The present invention is directed to transesterifying alcohol and malonic acid dimethyl ester to produce a malonic acid dialkyl ester acid (alkyl group has 2 or more carbon atoms) using the general formula as a catalyst. C
This is a method for producing malonic acid dialkyl esters, which is characterized by using an organic tin compound represented by I) or (II).

2゛、 Sn Tan 0 (1) 2,' (Note) However.

R1, R2: C, ~C8 alkyl group R3, R4,
R5, Rb: Ca-C8 alkyl group R7: C1-C
Transesterification catalyst (1) used in the alkyl basic invention of n.

(II) is commercially available as a stabilizer for vinyl chloride and as a raw material for agricultural chemicals, and is easily available. This catalyst is not affected by trace amounts of moisture in the reaction system, so there is no need for a dehydration step in advance, the reaction time is short because the catalyst activity does not decrease during the reaction, it does not cause side reactions, and there is no need for a washing step. Also, if the distillation residue is reused in the reaction,
It has the advantage of being able to be used again as a catalyst.

Examples of the transesterification catalyst (I) used in the present invention include dimethyltin oxide, ethylmethyltin oxide,
Examples include dipropyltin oxide, diisopropyltin oxide, dibutyltin oxide, and dioctyltin oxide, with dibutyltin oxide and dioctyltin oxide being particularly preferred.
As I), for example, bis(dibutylacetoxytin)
Oxide, bis(dibutyloctanoyloxytin)
oxide, bis(dibutyllauroyloxytin) oxide, bis(dibutylstearoyloxytin) oxide, bis(dioctyl acetoxytin) oxide, bis(dioctyl octanoyloxytin) oxide, bis(dioctyl lauroyloxytin) oxide, bis(dioctyl Examples include stearoyloxytin oxide, and in particular, it is preferable to use at least one member from the group consisting of bis(dibutyloctanoyloxytin) oxide, bis(dibutyllauroyloxytin) oxide, and bis(dibutylstearoyloxytin) oxide. preferable.

The amount of these catalysts used is 0.1 to 5.0 mol%, preferably 0.25 to 2.5 mol%, based on the raw material dimethyl malonate.
It is better to use mol%.

In the production method of the present invention, the alcohol used as a raw material is preferably used in an amount of 1.2 to 10 mol, preferably 2.0 to 5.0 mol, per 1 mol of dimethyl malonate.

Further, the reaction temperature is preferably carried out within the range of 80 to 150°C; below 80°C the catalyst activity is low, and above 150°C the amount of by-products increases.

Furthermore, benzene, toluene, hexane, etc. can be used as a reaction solvent, if necessary.

[Example] Example 1 In a flask equipped with a stirrer, a thermometer, and a 20-stage distillation column, 264.2 g of di/l malonate (
2.0 mol), ethanol 460.7g (10 mol)
, 4.98 g of dibutyltin oxide was added as a catalyst,
Heat with stirring. The reaction proceeded continuously by fractionating the produced methanol with ethanol and taking it out of the system.

The reaction was carried out for 15 hours, during which the tower top temperature was 63.0-6.
4.0, and the pot temperature was 81.0 to 86.0°C.

After the reaction, the reaction mixture was distilled under reduced pressure as it was, and the
304.4 g of a fraction with a temperature of 67.0°C and 15.0■■Hg was obtained. As a result of analyzing this fraction by NMR and IR, it was confirmed that it was diethyl malonate.

The yield of diethyl malonate based on the raw material dimethyl malonate was 95.0%.

Examples 2 to 8 The present invention was carried out in the same manner as in Example 1, except that the same reaction apparatus as in Example 1 was used, and the catalyst was added in an amount of 1 mol % based on the raw material dimethyl malonate. Table 1 shows examples of implementation.

Table 1 Examples 9 to 13 Table 2 shows examples in which the present invention was carried out using the same apparatus as in Example 1 and changing the type of alcohol in the same manner as in Example 1.

(The following is a blank space) [Effects of the Invention] As explained above, it is possible to produce dialkyl malonate with higher yield and purity than dimethyl malonate without complicated operations according to the present invention.
Became.

Claims (1)

[Scope of Claims] When alcohol and malonic acid dimethyl ester are transesterified to produce malonic acid dialkyl esters (alkyl group has 2 or more carbon atoms), general formula (I) or (II) is used as a catalyst. A method for producing malonic acid dialkyl esters, which comprises using the organotin compound represented by the formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (Note) However, R_1, R_2: Alkyl group of C_1 to C_8 R_3, R_4, R_5, R_6: C_4 ~C_8 alkyl group R_7: C_1 to C_1_7 alkyl group