阅读说明：本技术 使用氧化胺制备二碳酸二烷基酯的方法 (Method for preparing dialkyl dicarbonates using amine oxides ) 是由 克里斯托夫·霍夫曼 于 2019-07-04 设计创作，主要内容包括：本发明提供了使用氧化胺制备二碳酸二烷基酯的方法。本发明涉及一种用于使用特定的氧化胺作为催化剂由相应的氯甲酸烷基酯制备二碳酸二烷基酯的方法。(The present invention provides a process for preparing dialkyl dicarbonates using amine oxides. The invention relates to a method for producing dialkyl dicarbonates from the corresponding alkyl chloroformates using a specific amine oxide as catalyst.)

1. A process for preparing dialkyl dicarbonates by reacting the corresponding alkyl haloformates with at least one alkali metal hydroxide, alkaline earth metal hydroxide and/or carbonate in the presence of at least one water-immiscible organic solvent and in the presence of a catalyst, characterized in that the catalyst used is at least one compound of the formula (I)

Wherein the content of the first and second substances,

R¹and R²As linear or branched C₁-C₆-an alkyl group,

R³as linear or branched C₁₀-C₂₂-an alkyl group,

wherein R is¹And R²Are each independent of one another and may be the same or different.

2. The process according to claim 1, characterized in that the catalyst used is at least one compound of formula (I) according to claim 1, in which R is³At each timeIn this case straight-chain or branched dodecyl, undecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl or docosyl.

3. The process as claimed in claim 1 or 2, characterized in that the catalysts used are mixtures of compounds of the formula (I), characterized in that they comprise C having a linear or branched chain₁₀-、C₁₁-、C₁₂-、C₁₃-、C₁₄-、C₁₅-、C₁₆-、C₁₇-、C₁₈Different radicals R of alkyl radicals³。

4. Process according to at least one of claims 1 to 3, characterized in that the catalyst used is at least one compound of the formula (I) according to claim 1, in which R¹And R²Methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl and R³As linear or branched C₁₀-C₁₈-an alkyl group.

5. Process according to at least one of claims 1 to 4, characterized in that the catalyst used is at least one compound of the formula (I) according to claim 1, in which R¹And R²Methyl and R³＝C₁₀-C₁₆-an alkyl group.

6. Process according to at least one of claims 1 to 5, characterized in that the catalyst used is at least one compound of the formula (I) according to claim 1, in which R¹And R²Methyl and R³Dodecyl, tetradecyl, hexadecyl.

7. The process according to at least one of claims 1 to 6, characterized in that a compound of the formula (I) is usedThe substance being mixtures having C with straight or branched chain₁₂-、C₁₄-and C₁₆Different radicals R of alkyl radicals³And R is¹And R²(ii) methyl, and wherein R is based on the total weight of the compound of formula (I) used, wherein R is³＝C₁₂-the content of alkyl compounds is from 60% by weight to 80% by weight and wherein R³＝C₁₄-the content of alkyl compounds is from 19% by weight to 30% by weight and wherein R³＝C₁₆-the content of compounds of alkyl group is from 1% by weight to 10% by weight.

8. The process according to at least one of claims 1 to 7, characterized in that the dialkyl dicarbonates of the formula (II)

Wherein the content of the first and second substances,

R⁴is straight-chain or branched C₁-C₂₀-an alkyl group,

by reacting an alkyl haloformate of the formula (III)

Wherein the content of the first and second substances,

hal is halogen, preferably F, Cl, Br, I, especially chlorine, and

R⁴is straight-chain or branched C₁-C₂₀-an alkyl group.

9. The method of claim 8, wherein R is⁴Is methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl.

10. The process according to at least one of claims 1 to 9, characterized in that the alkali metal hydroxide or alkaline earth metal hydroxide and/or carbonate is used in the form of an aqueous solution.

11. The process according to at least one of claims 1 to 10, characterized in that at least one water-immiscible organic solvent from a series of water-immiscible aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, dialkyl carbonates or ethers and esters is used.

12. The process according to at least one of claims 1 to 11, characterized in that the amount of compound of the formula (I) used is 0.1 to 7 mol%, based on the haloformate.

13. The process according to at least one of claims 1 to 12, characterized in that the reaction of the haloformic ester used is carried out at a temperature between 15 ℃ and 19 ℃ under standard pressure.

14. The process according to at least one of claims 1 to 13, characterized in that the reaction is carried out in a continuous mode of operation.

15. The process according to at least one of claims 1 to 14, characterized in that the treatment of the reaction mixture for separating the dialkyl dicarbonate after the reaction is completed is effected by phase separation and subsequent multi-stage distillation of the organic phase.

Technical Field

The invention relates to a method for producing dialkyl dicarbonates from the corresponding alkyl chloroformates using a specific amine oxide as catalyst.

Background

Dialkyl dicarbonates are used, for example, as catalysts for oxidizing sterically demanding amines, as components of electrolyte fluids or as components of antimicrobial agents. Dialkyl dicarbonates are also known in the literature as dialkyl pyrocarbonates.

It is known from DE-B1210853 to react carbonyl halides with organic hydroxy compounds or their alkali metal or alkaline earth metal salts and also with water-immiscible organic solvents and at least equivalent amounts of alkali metal hydroxides or alkaline earth metal hydroxides or carbonates in a two-phase system and using catalytic amounts of tertiary amines or their quaternization products, where the amines used or their quaternization products are those which carry at least one nitrogen-bonded omega-hydroxyalkyl, omega-hydroxyalkyl ether or omega-hydroxyalkyl polyether group.

DE-A1418849 describes tertiary amines as particularly suitable catalysts for the preparation of acid derivatives, the tertiary nitrogen atom of which is not sterically hindered, except for tertiary amines which carry the same omega-hydroxyalkyl, omega-hydroxyalkyl ether or omega-hydroxyalkyl polyether groups as substituents on the nitrogen. Thus, in addition to triethylamine and tri-N-butylamine, amines which carry at least one methyl group on the nitrogen, such as, for example, N-methyl-di-N-stearylamine, are also used here. However, these catalysts have the disadvantage that, in particular, they catalyze not only the formation of the product but also the decomposition of the product, which leads to a reduction in the yield. Some of these catalysts are also toxic, degrade poorly in wastewater and may be difficult to remove from the reaction mixture due to their own decomposition during the reaction.

EP-A1747185 discloses a method for preparing dialkyl dicarbonates from alkyl haloformates by reacting them with alkali metal hydroxides or alkaline earth metal hydroxides or carbonates, wherein long-chain tertiary C is used₆-C₂₅-an alkylamine. Also, with these catalysts, the yields of product are not entirely satisfactory.

Disclosure of Invention

Therefore, there is a further need for a process for the preparation which provides the desired product in high yield.

Surprisingly, it has been found that dialkyl dicarbonates can be obtained particularly advantageously from alkyl haloformates by reaction with alkali metal hydroxides or alkaline earth metal hydroxides or carbonates if the specific ammonium oxide of the formula (I) is used as catalyst. They are characterized by high catalytic activity without causing decomposition of the final product. In addition, the yield of dialkyl dicarbonate using the compound of formula (I) is higher than that using a conventional tertiary amine.

The invention therefore relates to a process for preparing dialkyl dicarbonates by reacting the corresponding alkyl haloformates with alkali metal hydroxides or alkaline earth metal hydroxides and/or carbonates in the presence of a water-immiscible organic solvent and in the presence of a catalyst, characterized in that the catalyst used is at least one compound of the formula (I)

Wherein the content of the first and second substances,

R¹and R²As linear or branched C₁-C₆-an alkyl group,

R³as linear or branched C₁₀-C₂₂-an alkyl group,

wherein R is¹And R²Are each independent of one another and may be the same or different.

In carrying out the process according to the invention, preference is given to using as catalyst a compound of the formula (I) in which R is¹And R²Methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl and R³As linear or branched C₁₀-C₁₈-an alkyl group.

Particular preference is given to using as catalyst a compound of the formula (I) in which R is¹And R²Methyl and R³＝C₁₂-C₁₈-an alkyl group.

In one embodiment of the process according to the invention, the catalyst used is a compound of the formula (I) in which R is³In each case straight-chain or branched dodecyl, undecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl or docosyl. Preferably, R³Dodecyl, tetradecyl, hexadecyl and octadecyl.

In another embodiment of the process according to the invention, the catalyst is a compound of formula (I), wherein R is¹And R²Methyl and R³Dodecyl, tetradecyl and hexadecyl.

It is also possible to use mixtures of any desired catalysts in carrying out the process according to the invention.

In a further preferred embodiment, the catalyst used is a mixture of compounds of the formula (I) which comprises C having a linear or branched chain₁₀-、C_11-、C₁₂-、C₁₃-、C₁₄-、C₁₅-、C₁₆-、C₁₇-or C₁₈Different radicals R of alkyl radicals³。

It is even more preferred to administer a mixture of compounds of formula (I) comprising C with a linear or branched chain₁₂-、C₁₄-and C₁₆Different radicals R of alkyl radicals³And wherein R¹And R²Is methyl.

In a further preferred embodiment, the catalyst used is a mixture of compounds of the formula (I) which comprises C having a linear or branched chain₁₂-、C₁₄-and C₁₆Different radicals R of alkyl radicals³And R is¹And R²(ii) methyl, and wherein R is based on the total weight of the compound of formula (I) used, wherein R is³＝C₁₂-the content of alkyl compounds is from 60% by weight to 80% by weight and wherein R³＝C₁₄-the content of alkyl compounds is from 19% by weight to 30% by weight and wherein R³＝C₁₆-the content of compounds of alkyl group is from 1% by weight to 10% by weight.

In a further preferred embodiment, the compound of the formula (I) used is a mixture of lauryl dimethyldiamine oxide (N, N-dimethyldodecane-1-amine oxide), myristyl dimethylamine oxide (N, N-dimethyltetradecane-1-amine oxide) and cetyl dimethylamine oxide (N, N-dimethylhexadecane-1-amine oxide). These catalysts are preferably used in a content of 60% by weight to 80% by weight of lauryl dimethylamine oxide, 19% by weight to 30% by weight of myristyl dimethylamine oxide and 1% by weight to 10% by weight of cetyl dimethylamine oxide, based on the total weight of the compound of formula (I) used.

In a further preferred embodiment, the catalyst used may be a mixture of compounds of the formula (I) in which the radical R is in the context of the above disclosure¹、R²And R³In any desired manner. In a further preferred embodiment, the catalyst is dissolved in water, optionally in the presence of a water-miscible solvent, before being used in the process according to the invention. The water-miscible solvent used is preferably an alcoholSuch as in particular diols. The compound of formula (I) is preferably present in water or in a mixture with water and a water-miscible solvent in a concentration of between 25% by weight and 75% by weight.

The tertiary amines typically used to prepare the catalysts are readily oxidized to amine oxides by hydrogen peroxide or peroxycarboxylic acids. Catalysts such as N, N-dimethyldodecane-1-amine oxide are commercially available and are sold by the company tornada (Lonza) for example under the name Barlox12 or Barlox 1260. Their preparation is also known to the person skilled in the art.

The process according to the invention provides for the preparation of dialkyl dicarbonates of the formula (II)

Wherein the content of the first and second substances,

R⁴is straight-chain or branched C₁-C₂₀-an alkyl group,

by reacting an alkyl haloformate of the formula (III)

Wherein the content of the first and second substances,

hal is halogen, preferably F, Cl, Br, I, especially chlorine, and

R⁴is straight-chain or branched C₁-C₂₀-an alkyl group.

In the formulae (II) and (III), R⁴Preferably straight or branched C₁-C₈-alkyl, particularly preferably the group-CH-R⁵R⁶Wherein R is⁵And R⁶Each independently of the other being H or C, which is linear or branched₁-C₇-an alkyl group. R⁴In particular methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl. R⁴Methyl is particularly preferred, so that dimethyl dicarbonate is obtained as compound of formula (II).

Alkali metal hydroxide or alkaline earth metal hydroxide or carbonate comprisesFor example, LiOH, NaOH, KOH, LiCO₃、Na₂CO₃、K₂CO₃. Preference is given to using alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, which are preferably used in the form of aqueous solutions. For example, 1 to 50% by weight of an aqueous alkali metal hydroxide solution may be used. Preference is given to solutions of 5 to 35% by weight, particularly preferably 10 to 25% by weight. The alkali metal hydroxide or alkaline earth metal hydroxide or carbonate is preferably used in an amount of 80 to 120 mol%, based on the haloformate used. This amount is particularly preferably in the range from 90 mol% to 115 mol%, particularly preferably in the range from 95 mol% to 115 mol%.

Water-immiscible organic solvents include, for example, water-immiscible aliphatic and aromatic hydrocarbons, halogenated hydrocarbons, ethers or esters and also dialkyl carbonates. Preference is given to cyclohexane, toluene, xylene, dichloromethane and diethyl ether, especially toluene and dichloromethane. Very particular preference is given to using toluene.

The water-immiscible organic solvent can be used, for example, in an amount of from 20 to 90% by weight, preferably from 30 to 80% by weight, particularly preferably from 40 to 80% by weight, based on the haloformic ester of the formula (III).

The catalysts of the formula (I) are generally used in amounts of from 0.1 to 7 mol%, preferably from 0.5 to 5 mol%, based on the haloformic ester of the formula (III). The catalyst of formula (I) is even more preferably used in an amount of from 0.5 to 3 mol%.

The process according to the invention can be carried out at a pressure in the range from 1 to 10 bar, preferably from 1 to 1.5 bar.

The reaction temperature may be, for example, between-10 ℃ and the boiling temperature (at standard pressure) of the haloformate used. Preferably in the range of 0 ℃ to 50 ℃. Even more preferably, the reaction temperature is between 15 ℃ and 19 ℃.

While carrying out the process according to the invention, it is advantageous to ensure adequate mixing, for example by using stirrers, baffles or circulation pumps.

The process according to the invention can be carried out both batchwise and continuously. In batch mode, the reaction is preferably carried out in a stirred tank. In this context, the reaction is generally terminated after 10 minutes to 3 hours, depending on the size of the batch and the current cooling power.

The process according to the invention is preferably carried out continuously using stirred tanks, a cascade of stirred tanks or a tubular reactor. In this case, the average residence time in the reactor is generally between 1 and 60 minutes, preferably between 6 and 45 minutes and particularly preferably between 10 and 30 minutes.

After carrying out the process according to the invention, the reaction mixture separates into two phases, optionally after cooling. In addition to the solvent, the organic phase also contains the dialkyl dicarbonate produced and possibly small amounts of unreacted haloformates and also the catalyst. In addition to water, the aqueous phase also contains the inorganic salts formed.

The product is already present in high purity, so that no further distillative separation is required, apart from phase separation.

By using the catalyst used according to the invention, dialkyl dicarbonates can be prepared in high yields.

Detailed Description

Examples of the invention

Example 1

A mixture of 18.87g (0.2mol) of Methyl Chloroformate (MC) and 14.83g of toluene was initially charged to a reaction vessel and then 3.57g of Barlox12 (Dragon Sand, Basel) (0.0045mol) was introduced (30% by weight of 70% lauryl dimethyl diamine oxide in water (amine oxide of formula (I) where R is¹And R²Methyl, R³＝C₁₂-alkyl), 26% myristyl dimethyl amine oxide (amine oxide of formula (I) wherein R is¹And R²Methyl, R³＝C₁₄Alkyl and 4% hexadecyldimethylamine oxide (amine oxide of formula (I), where R is¹And R²Methyl, R³＝C₁₆Alkyl) and 62.73g of about 14% NaOH (0.22 mol).

The mixture was reacted at 17 ℃ with vigorous stirring. After about 20 minutes, the phases separated.

The crude yield was about 95% based on the amount of MC used.

COMPARATIVE EXAMPLE 1 (Using Tertiary amine as catalyst)

An example of the invention is already known in a similar form from EP 1747185a (example 3).

A mixture of 20.41g (0.22mol) of MC and 14.78g of toluene was initially charged in the reaction vessel and then 0.54g (0.0015mol) of Alamine 308 (triisooctylamine) and 64.27g of about 14% NaOH (0.22mol) were introduced.

The mixture was reacted at 12 ℃ with vigorous stirring. After about 20 minutes, the phases separated.

The crude yield was about 91% based on the amount of MC used.