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Esterification method for preparing azodicarbonic acid

A technology of dialkyl azodicarboxylate and diethyl azodicarboxylate, which is applied in the field of dialkyl azodicarboxylate represented by the formula ROOCN=NCOOR, can solve non-compliance, high price and environmental pollution problems such as mild reaction conditions, low production costs, and short process routes

Active Publication Date: 2013-07-10
SHANDONG NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Compared with the previous one, this method uses water as a solvent to carry out the first step reaction, which reduces the by-products substituted on one side and improves the reaction yield. However, this method still uses chloroformate and hydrazine hydrate as raw materials. And in the second step, chlorine gas is used instead as an oxidant to increase the risk of the reaction, and the reaction end point is difficult to control, and the environment is also greatly polluted
[0006] The above traditional process route uses substances such as chloroformate and hydrazine hydrate as raw materials. These substances are not only expensive, but also highly toxic; the oxidation process requires the use of highly toxic or corrosive concentrated nitric acid, nitrogen oxides, chlorine and other substances.
The synthesis process is seriously polluting and does not meet the standards of modern green chemistry

Method used

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  • Esterification method for preparing azodicarbonic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The preparation of embodiment 1 diisopropyl azodicarboxylate

[0031] In a 250mL three-necked round-bottomed flask equipped with a magnetic stirrer, a 25mL constant pressure dropping funnel and a rectification device, add 100mL of isopropanol, and under nitrogen protection, add 0.46g (0.02mol) of sodium metal, and wait for the sodium metal to After complete dissolution, 14.60 g of dimethyl azodicarboxylate was added dropwise and reacted for 24 hours under reflux until no methanol evaporated to stop the reaction. The reaction solution was neutralized to pH 7 with 10% hydrochloric acid (mass fraction, the same below), and the organic phase was extracted three times with dichloromethane. The organic phases were combined, dried overnight (10 h) over anhydrous sodium sulfate, and unreacted Isopropanol was recovered and distilled under reduced pressure to obtain 16.52 g of wine-red diisopropyl azodicarboxylate (81.8% yield).

[0032] 1 HNMR (CDCl 3 ,300MHz)δ(ppm):5.33-5.43...

Embodiment 2

[0034] The preparation of embodiment 2 diisoamyl azodicarboxylate

[0035]In a 250mL three-necked round-bottomed flask equipped with a magnetic stirrer, a 25mL constant pressure dropping funnel and a rectification device, add 100mL of isoamyl alcohol, and under nitrogen protection, add 0.46g (0.02mol) of sodium metal, and wait for the sodium metal to After complete dissolution, 14.60 g of dimethyl azodicarboxylate was added dropwise, and the reaction was carried out under reflux for 16 hours until no methanol evaporated to stop the reaction. The reaction solution was neutralized with 10% hydrochloric acid solution to pH 7, the organic phase was extracted three times with dichloromethane, the organic phase was combined, dried overnight (10 h) over anhydrous sodium sulfate, unreacted isobutanol was evaporated to recover, and the Distilled under pressure to obtain 21.91 g of orange-red diisoamyl azodicarboxylate (85.2% yield).

[0036] 1 HNMR (CDCl 3 ,300MHz)δ(ppm):4.13(4H,t,C...

Embodiment 3

[0039] The preparation of embodiment 3 dicyclohexyl azodicarboxylate

[0040] In a 250mL three-necked round-bottomed flask equipped with a magnetic stirrer, a 25mL constant-pressure dropping funnel and a rectification device, add 100mL of cyclohexanol, and under nitrogen protection, add 0.46g (0.02mol) of sodium metal, and wait for the sodium metal to After complete dissolution, 14.60 g of dimethyl azodicarboxylate was added dropwise, and the reaction was carried out under reflux for 12 hours until no methanol evaporated to stop the reaction. The reaction solution was neutralized with 10% hydrochloric acid solution to a pH value of 6, the organic phase was extracted three times with dichloromethane, the organic phase was combined, dried over anhydrous sodium sulfate (8h), unreacted cyclohexanol was distilled off and recovered, and Ethyl acetate-petroleum ether mixture (the volume ratio of the two is 1:5) was recrystallized to obtain 22.63 g of dicyclohexyl azodicarboxylate as ...

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Abstract

The invention discloses a method for preparing dialkyl azodicarbonic acid. The method comprises the steps of: mixing dimethyl azodicarbonic acid or diethyl azodicarbonic acid with sodium alkoxide solution, heating and reacting for 1-24h, and carrying out transesterification reaction between the dimethyl azodicarbonic acid or diethyl azodicarbonic acid and alcohol under the catalytic action of the sodium alkoxide; after the reaction is completed, regulating the pH value of the solution to 6-8, extracting an organic phase for 2-3 times with dichloromethane, combining the organic phases, drying for 8-12h with anhydrous sodium sulfate, and then performing reduced pressure distillation or recrystallization to obtain dialkyl azodicarbonic acid ROOCN=NCOOR, wherein R is alkyl containing 2-16 carbon atoms. According to the method, the dimethyl azodicarbonic acid or diethyl azodicarbonic acid is selected as raw materials, and is easily available; and the production cost is low, the economy is good, and pollution to the environment does not exist; the method for preparing the dialkyl azodicarbonic acid through esterification is simple to operate, short in process route, mild in reaction conditions, and high in yield, as well as suitable for industrialized development.

Description

technical field [0001] The invention relates to a method for preparing dialkyl azodicarboxylate represented by formula ROOCN=NCOOR. Background technique [0002] Dialkyl azodicarboxylate is a class of compounds with both azo and carboxyl functional groups, the more common ones are dimethyl azodicarboxylate (DMAD), diethyl azodicarboxylate (DEAD), azo Diisopropyl dicarboxylate (DIAD), dibenzyl azodicarboxylate (DBAD). Due to their unique electronic and structural properties, dialkyl azodicarboxylates have been widely used as a multifunctional reagent in organic synthesis, especially in the Mitsunobu reaction, amination of carbonyl compounds, unsaturated hydrocarbon It plays a very important role in the ammoniation and synthesis of heterocyclic compounds. Azodicarboxylates can also be used as oxidants for the dehydrogenation and oxidation reactions of alcohols and amines. In addition, dialkyl azodicarboxylate is an important class of intermediates and catalysts, widely used...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C281/20
Inventor 张志德满成娜吕硕王重斌
Owner SHANDONG NORMAL UNIV
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