阅读说明：本技术 一种合成乳酰肼的方法 (Method for synthesizing lactoyl hydrazine ) 是由 康世民 刘越钊 钟沛金 章羽仪 庞翊淇 陈素霞 邱杨辉 于 2021-07-14 设计创作，主要内容包括：本发明提供了一种合成乳酰肼的方法,以绿色可再生聚乳酸为原料,在温和温度下实现乳酰肼的制备。克服了现有乳酰肼合成原料具有不可再生、价格昂贵等缺点,开发以绿色可再生的聚乳酸来合成乳酰肼的方法。基于原料聚乳酸质量,乳酰肼产率达到139 wt%。本发明通过一步反应,实现把聚乳酸高效转化为乳酰肼,具有工业化应用前景。(The invention provides a method for synthesizing lactoyl hydrazine, which takes green renewable polylactic acid as a raw material and realizes the preparation of lactoyl hydrazine at a mild temperature. Overcomes the defects that the existing lactohydrazide synthesis raw material is non-renewable and expensive, and develops a method for synthesizing lactohydrazide by using green renewable polylactic acid. Based on the mass of the polylactic acid as the raw material, the yield of the lactoyl hydrazine reaches 139 wt%. The invention realizes the high-efficiency conversion of polylactic acid into lactohydrazide through one-step reaction, and has industrial application prospect.)

1. A method for synthesizing lactyl hydrazine is characterized in that: putting polylactic acid and a solvent into a reaction vessel for reaction to obtain the lactohydrazide.

2. A method of synthesizing lactohydrazide according to claim 1, wherein: the solvent is hydrazine hydrate.

3. A method of synthesizing lactohydrazide according to claim 1, wherein: the reaction time is 30-70 ℃ and 1-24 h.

4. A method of synthesizing lactohydrazide according to claim 1, wherein: the mass-volume ratio of the polylactic acid to the hydrazine hydrate is 1: (1-3).

5. The method according to any one of claims 1-4, wherein: and cooling to room temperature after reaction to obtain homogeneous reaction liquid, and performing vacuum rotary evaporation on the homogeneous reaction liquid at 90 ℃ to remove residual hydrazine hydrate solution to obtain a solid product.

6. The method of claim 5, wherein: and soaking the solid product with chloroform for two times to remove the polylactic acid or other side products which are not completely reacted to obtain the lactohydrazide.

7. The method of claim 6, wherein: placing polylactic acid and hydrazine hydrate in a reaction vessel, reacting for 1-24h at 30-70 ℃, cooling to room temperature after reaction to obtain homogeneous reaction liquid, carrying out vacuum rotary evaporation on the homogeneous reaction liquid at 90 ℃ to remove residual hydrazine hydrate solution to obtain a solid product, and soaking the solid product with chloroform twice to remove unreacted polylactic acid or other byproducts to obtain lactohydrazide.

8. The method of claim 7, wherein: the yield of lactohydrazide reached 139 wt% based on the mass of polylactic acid.

Technical Field

The invention relates to the fields of organic synthesis, pharmaceutical chemicals and the like, in particular to a method for synthesizing lactyl hydrazine.

Background

Lactohydrazide (also known as 2-hydroxypropionhydrazide, English name Lacthydrazide; ingredientSub-formula C₃H₈N₂O₂) Is an important fine chemical intermediate. The lactohydrazide contains active groups of hydroxyl and hydrazide, and has wide application, such as application in the fields of organic synthesis, pharmaceutical chemistry and the like. The lactic hydrazide can be prepared from expensive fine chemical methyl 2-hydroxypropionate, but the large-scale industrial production and application of the lactic hydrazide are limited.

The preparation of high-value fine chemicals by using biomass-based polyesters (such as polyhydroxyalkanoates, polylactic acid and the like) is an important technology. For example, polyhydroxyalkanoate can be utilized to prepare crotonic acid, amide compounds, hydrazide compounds, etc. Compared with polyhydroxyalkanoate, polylactic acid is a high polymer with completely different structures, and has the characteristics of relatively higher stability and relatively higher degradation difficulty. For example, the pyrolysis of polyhydroxyalkanoate can yield a high yield of the chemical crotonic acid (2-butenoic acid), while the pyrolysis of polylactic acid can hardly yield a high yield of acrylic acid. The structural monomer of the polylactic acid is lactic acid (2-hydracrylic acid), and carboxyl (carboxyl is at 1 position) and hydroxyl (hydroxyl is at 2 position) of the polylactic acid are adjacent to each other, so that intramolecular hydrogen bonds can be formed, and the stability is high. At present, polylactic acid has the characteristics of no toxicity, plasticity, easy degradation and the like, and is widely used for preparing degradable plastics. In the near future, the generation of a large amount of polylactic acid plastic solid wastes can be expected, and the development of high-valued degradation utilization technology has great significance for preparing polylactic acid or plastic solid wastes thereof into high-valued chemicals (such as lactohydrazide).

Disclosure of Invention

The invention provides a method for synthesizing lactoyl hydrazine, overcomes the defects that the existing lactoyl hydrazine synthesis raw materials are non-renewable and expensive, and develops a method for synthesizing lactoyl hydrazine by using green and renewable polylactic acid.

The technical scheme for realizing the invention is as follows:

a method for synthesizing lactoyl hydrazine, which comprises the following steps: putting polylactic acid and hydrazine hydrate into a reaction vessel, reacting for 1-24h at 30-70 ℃, cooling to room temperature after reaction to obtain homogeneous reaction liquid, and performing vacuum rotary evaporation on the homogeneous reaction liquid at 90 ℃ to remove residual hydrazine hydrate solution to obtain a solid product, namely lactohydrazide.

Preferably, the reaction temperature is from 30 ℃ to 70 ℃. Elevated temperatures are beneficial for faster reactions, but excessive temperatures (e.g., >70 degrees) increase by-product and energy consumption; at low temperatures (e.g., 20 c) the reaction rate is too slow and the reaction time required is too long.

Preferably, the mass-to-volume ratio of polylactic acid to hydrazine hydrate is 1: (1-3), g/mL.

The invention has the beneficial effects that: the method provided by the invention takes green renewable polylactic acid as a raw material, and realizes the preparation of the lactohydrazide at a mild temperature. Based on the mass of the polylactic acid as the raw material, the yield of the lactoyl hydrazine reaches 139 wt%. The invention realizes the high-efficiency conversion of polylactic acid into lactohydrazide through one-step reaction, and has industrial application prospect.

It is worth noting that lactic acid, a structural monomer of polylactic acid, is difficult to react with hydrazine hydrate to generate lactohydrazide under the conditions of the invention, and lactic acid is rarely detected in the polylactic acid reaction product, which indicates that the degradation of polylactic acid to generate lactic acid is not a main path of lactohydrazide. The mechanism of the reaction process of the invention is that hydrazine hydrate directly generates addition elimination reaction with ester bonds in the polylactic acid high-polymer structure, and the reaction realizes not only the degradation of polylactic acid high polymer but also the generation of lactohydrazide, thereby realizing the high-valued degradation and utilization of polylactic acid. To this end, the realization of the technology of the present invention is directly related to the characteristic high-aggregation structure unique to polylactic acid, and the structure capable of being sufficiently contacted and reacted with hydrazine hydrate.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a GC analysis chart of the product obtained in example 1.

FIG. 2 is a graph showing the mass spectrum analysis of the product obtained in example 1.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

A method for synthesizing lactoyl hydrazide, which comprises the following steps:

(1) 10 g of polylactic acid and 30 mL of hydrazine hydrate are placed in a 50 mL reactor, the reactor is heated to 40 ℃ at 6 ℃/min and kept at 40 ℃ for 12 h.

(2) After the reaction is finished, cooling to room temperature to obtain homogeneous reaction liquid; the homogeneous reaction solution was rotary evaporated in vacuo at 90 ℃ to remove the residual hydrazine hydrate solution and filtered to give 13.9g of a white product. The product was determined to be lactohydrazide by gas chromatography-mass spectrometry (see FIG. 1) and mass spectrometry (see FIG. 2) of the white product dissolved in methanol.

Example 2

A method for synthesizing lactoyl hydrazide, which comprises the following steps:

(1) 10 g of polylactic acid and 20 mL of hydrazine hydrate were placed in a 50 mL reactor. The reactor was warmed to 60 ℃ at 6 ℃/min and held at 60 ℃ for 12 h.

(2) After the reaction is finished, cooling to room temperature to obtain homogeneous reaction liquid; the solution contained 12.8g lactohydrazide by GC-MS quantitative analysis.

Example 3

(1) 10 g of polylactic acid and 20 mL of hydrazine hydrate were placed in a 50 mL reactor. The reactor was warmed to 30 ℃ at 6 ℃/min and held at 30 ℃ for 24 h.

(2) After the reaction is finished, cooling to room temperature to obtain homogeneous reaction liquid; the solution contained 12.7g lactohydrazide by GC-MS quantitative analysis.

Example 4

(1) 10 g of polylactic acid and 30 mL of hydrazine hydrate were placed in a 50 mL reactor. The reactor was warmed to 70 ℃ at 6 ℃/min and held at 70 ℃ for 3 h.

(2) After the reaction is finished, cooling to room temperature to obtain homogeneous reaction liquid; the solution contained 10.8g lactohydrazide by GC-MS quantitative analysis.

Example 5

A method for synthesizing lactoyl hydrazide, which comprises the following steps:

(1) 10 g of polylactic acid and 20 mL of hydrazine hydrate were placed in a 50 mL reactor. The reactor was warmed to 70 ℃ at 6 ℃/min and held at 70 ℃ for 1 h.

(2) After the reaction is finished, cooling to room temperature to obtain homogeneous reaction liquid; the solution contained 10.4g lactohydrazide by GC-MS quantitative analysis.

Example 6

A method for synthesizing lactoyl hydrazide, which comprises the following steps:

(1) 10 g of polylactic acid and 20 mL of hydrazine hydrate were placed in a 50 mL reactor. The reactor was warmed to 50 ℃ at 6 ℃/min and held at 50 ℃ for 12 h.

(2) After the reaction is finished, cooling to room temperature to obtain homogeneous reaction liquid; the solution contained 12.7g lactohydrazide by GC-MS quantitative analysis.

Example 7

A method for synthesizing lactoyl hydrazide, which comprises the following steps:

(1) 10 g of polylactic acid and 10 mL of hydrazine hydrate were placed in a 50 mL reactor. The reactor was warmed to 60 ℃ at 6 ℃/min and held at 60 ℃ for 18 h.

(2) After the reaction is finished, cooling to room temperature to obtain homogeneous reaction liquid; the solution contained 9.4g lactohydrazide by GC-MS quantitative analysis.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.