Method for co-producing butyraldehyde dibutyl acetal and butyl butyrate

Abstract

The invention discloses a method for co-producing butyraldehyde dibutyl acetal and butyl butyrate, butyl nitrite and butanol react, butyraldehyde dibutyl acetal is directly prepared without adding a catalyst, and butyl butyrate is co-produced in the reaction. The method has the advantages of simple raw materials, no catalyst and low production cost. In conclusion, the preparation method is simple to operate, does not need a catalyst and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to a method for co-producing butyraldehyde dibutyl acetal and butyl butyrate, and belongs to the field of fine chemicals. Background Art

[0002] As a class of compounds containing ether bonds, acetals have been widely used in the production of solvents, dyes, plastics and wetting agents due to their excellent stability and compatibility. Their unique odor characteristics make them useful as cosmetic flavoring agents or food additives; at the same time, acetals also perform well as antifreeze agents in biodiesel fuels. In addition, when acetal compounds are used as crosslinking agents, the acetal degree of the synthetic system can be gradually increased by introducing aldehyde groups and carbonyl groups, constructing a three-dimensional network structure, thereby enhancing the stability of the material and improving the performance of the packaging material. Therefore, the synthesis research of acetals has attracted much attention from researchers. For example, butyraldehyde dibutyl acetal, as a colorless liquid, has a special rubber smell and excellent solubility. It is soluble in alcohol and ether, but almost insoluble in water. It can be used as a starter, additive and intermediate in organic synthesis, and is also an important component of fragrances and coating solvents.

[0003] In the traditional acetal preparation method, the acetal reaction is usually carried out in two steps: first, reacting with alcohols under the catalysis of acid to generate unstable hemiacetal; then, the hemiacetal is dehydrated with another molecule of alcohol to form acetal. Chinese patent CN113999093A discloses a method for preparing acetal, which uses alcohol as a raw material, air as an oxidant and a water-carrying agent, and sequentially performs oxidative dehydrogenation and dehydration condensation reactions through two parallel reactors to prepare acetal. However, the reaction process of this method is complicated and requires additional catalysts. Chinese patent CN103936570A and document Green Chem., 2014, 16, 4076 disclose a method for directly preparing acetal using Pt / TiO2 photocatalyst to catalyze alcohol. Although this method has good selectivity, it requires the use of light of a specific wavelength and a precious metal catalyst, resulting in high cost and is not conducive to large-scale application. At present, industrial acetal synthesis mainly relies on homogeneous acidic catalysts, such as H2SO4, HCl, etc., and a few use transition metals as reaction catalysts, such as Rh, Pt, Pd.

[0004] In order to develop a cheap, green, environmentally friendly and sustainable method for preparing acetal, the present invention proposes to utilize nitrite to react with alcohol to directly prepare acetal without the need for an external catalyst, and a small amount of by-product ester compounds can also be generated during the reaction. Summary of the invention

[0005] The present invention aims to provide a low-cost, green and environmentally friendly method for the co-production of butyraldehyde dibutyl acetal and butyl butyrate to solve the shortcomings of the above-mentioned background technology.

[0006] The present invention uses butyl nitrite and butanol as raw materials to selectively synthesize acetals without a catalyst, and simultaneously by-produces butyl butyrate. The reaction conditions of this invention are mild, the process method is simple, and the selectivity of acetal is above 70%. The reaction process is as follows: The present invention is realized through the following technical solutions: Add butyl nitrite and n-butanol with a molar ratio of 1:20 to 1:40 into the reaction kettle, heat up to 60 - 180 °C under normal pressure, react for 1 - 24 h, and cool to room temperature to obtain the main product butyraldehyde dibutyl acetal and the by-product butyl butyrate.

[0007] Compared with the prior art, the present invention has the characteristics of simple process, no catalyst, mild reaction conditions, and easy operation. Description of the Drawings

[0008] Figure 1 It is the reaction gas chromatogram of Example 1 of the present invention. Detailed Embodiments

[0009] The following further explains and illustrates the present invention in combination with specific embodiments.

[0010] Example 1 Add 1 mmol of butyl nitrite into 2.5 mL of n-butanol, continuously stir magnetically under normal pressure, control the reaction temperature at 160 °C, and react for 24 h. After the reaction, gas chromatography ( Figure 1 ) analysis shows that the conversion rate of butyl nitrite is 77%, the yields of butyraldehyde dibutyl acetal and butyl butyrate are 66% and 11% respectively, and the selectivity of butyraldehyde dibutyl acetal is 86%.

[0011] Example 2 Add 1.5 mmol of butyl nitrite into 2.5 mL of n-butanol, continuously stir magnetically under normal pressure, control the reaction temperature at 160 °C, and react for 24 h. After the reaction, gas chromatography analysis shows that the conversion rate of butyl nitrite is 75%, the yields of butyraldehyde dibutyl acetal and butyl butyrate are 60% and 15% respectively, and the selectivity of butyraldehyde dibutyl acetal is 80%.

[0012] Example 3 Add 2 mmol of butyl nitrite into 2.5 ml of n-butanol, continuously stir magnetically under normal pressure, control the reaction temperature at 160 °C, and react for 24 h. After the reaction, gas chromatography analysis shows that the conversion rate of butyl nitrite is 72%, the yields of butyraldehyde dibutyl acetal and butyl butyrate are 52% and 20% respectively, and the selectivity of butyraldehyde dibutyl acetal is 72%.

[0013] Example 4 1 mmol of butyl nitrite was added to 2.5 mL of n-butanol, and the mixture was continuously stirred magnetically under atmospheric pressure. The reaction temperature was controlled at 170 °C, and the reaction time was 24 h. After the reaction, gas chromatography analysis showed that the conversion rate of butyl nitrite was 79%, the yields of butyraldehyde dibutyl acetal and butyl butyrate were 61% and 18% respectively, and the selectivity of butyraldehyde dibutyl acetal was 76%.

[0014] Example 5 1.5 mmol of butyl nitrite was added to 2.5 mL of n-butanol, and the mixture was continuously stirred magnetically under atmospheric pressure. The reaction temperature was controlled at 170 °C, and the reaction time was 24 h. After the reaction, gas chromatography analysis showed that the conversion rate of butyl nitrite was 78%, the yields of butyraldehyde dibutyl acetal and butyl butyrate were 58% and 20% respectively, and the selectivity of butyraldehyde dibutyl acetal was 74%.

[0015] Example 6 2 mmol of butyl nitrite was added to 2.5 mL of n-butanol, and the mixture was continuously stirred magnetically under atmospheric pressure. The reaction temperature was controlled at 170 °C, and the reaction time was 24 h. After the reaction, gas chromatography analysis showed that the conversion rate of butyl nitrite was 75%, the yields of butyraldehyde dibutyl acetal and butyl butyrate were 53% and 22% respectively, and the selectivity of butyraldehyde dibutyl acetal was 70%.

[0016] Example 7 2 mmol of butyl nitrite was added to 2.5 mL of n-butanol, and the mixture was continuously stirred magnetically under atmospheric pressure. The reaction temperature was controlled at 180 °C, and the reaction time was 24 h. After the reaction, gas chromatography analysis showed that the conversion rate of butyl nitrite was 88%, the yields of butyraldehyde dibutyl acetal and butyl butyrate were 70% and 18% respectively, and the selectivity of butyraldehyde dibutyl acetal was 80%.

[0017] Example 8 2 mmol of butyl nitrite was added to 4 mL of n-butanol, and the mixture was continuously stirred magnetically under atmospheric pressure. The reaction temperature was controlled at 180 °C, and the reaction time was 24 h. After the reaction, gas chromatography analysis showed that the conversion rate of butyl nitrite was 83%, the yields of butyraldehyde dibutyl acetal and butyl butyrate were 64% and 19% respectively, and the selectivity of butyraldehyde dibutyl acetal was 77%.

[0018] Example 9 2 mmol of butyl nitrite was added to 2.5 mL of n-butanol, and the mixture was continuously stirred magnetically under atmospheric pressure. The reaction temperature was controlled at 180 °C, and the reaction time was 24 h. After the reaction, gas chromatography analysis showed that the conversion rate of butyl nitrite was 81%, the yields of butyraldehyde dibutyl acetal and butyl butyrate were 61% and 20% respectively, and the selectivity of butyraldehyde dibutyl acetal was 74%.

[0019] Example 10 1 mmol of amyl nitrite was added to 2.5 mL of n-pentanol, and the mixture was continuously stirred magnetically under atmospheric pressure. The reaction temperature was controlled at 160 °C, and the reaction time was 24 h. After the reaction, gas chromatography analysis showed that the conversion rate of amyl nitrite was 80%, the yields of pentaldehyde di-n-pentyl acetal and butyl butyrate were 70% and 10% respectively, and the selectivity of pentaldehyde di-n-pentyl acetal was 87%.

[0020] It should be understood that the above examples are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for co-producing butyraldehyde dibutyl acetal and butyl butyrate, characterized in that: Add butyl nitrite and n-butanol with a molar ratio of 1:20 to 1:40 into the reaction kettle, heat up to 60-180 °C under atmospheric pressure, react for 1-24 h, and cool to room temperature to obtain the main product butyraldehyde dibutyl acetal and the by-product butyl butyrate.

2. The method for co-producing butyraldehyde dibutyl acetal and butyl butyrate according to claim 1, wherein: The yield of the butyraldehyde dibutyl acetal is 60%-70%, the selectivity of the butyraldehyde dibutyl acetal is above 70%, and the yield of the butyl butyrate is 10%-20%.

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