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Method for preparing lactic acid through selective catalytic conversion of ethylene glycol

A catalytic conversion and ethylene glycol technology, applied in chemical instruments and methods, preparation of organic compounds, carboxylate preparation, etc., can solve the problems of large-scale production limitations, dilute product concentration, and easy poisoning fermentation cycle, etc., to achieve reaction High conversion efficiency and easy operation

Active Publication Date: 2019-10-22
FUDAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional fermentation process is becoming more and more difficult to meet the relevant needs. Although biological fermentation has the advantages of mild reaction conditions and good selectivity, due to the disadvantages of expensive enzyme catalysts, easy poisoning, long fermentation cycle, dilute product concentration, and difficult purification, etc. , its large-scale production is subject to certain restrictions
[0004] At present, there are no reports at home and abroad on the use of ethylene glycol as a raw material to prepare lactic acid examples

Method used

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  • Method for preparing lactic acid through selective catalytic conversion of ethylene glycol
  • Method for preparing lactic acid through selective catalytic conversion of ethylene glycol
  • Method for preparing lactic acid through selective catalytic conversion of ethylene glycol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] The preparation of embodiment 1 azacyclic carbene iridium complex 1a:

[0053]

[0054] Under nitrogen, add a stirrer and cyclooctadiene iridium chloride dimer (0.33 g) into a Schlenk tube, pump and exchange air three times, and add 10 mL each of dichloromethane and tetrahydrofuran with a syringe. After the solution was clarified, potassium tert-butoxide (0.11 g) was added, sealed and stirred at room temperature for 1 h. After the color of the solution changed from red to reddish brown, 1,3-dimethylbenzimidazole tetrafluoroborate (0.23 g) was added, sealed and stirred at room temperature for 4 h. The reaction solution was separated by column to obtain 1a. Yield: 0.47 g, 90%.

[0055] NMR analysis: 1 H NMR (400MHz, CDCl 3 )δ=7.32–7.22(m,4H),4.74(s,2H),4.17(s,6H),2.98(s,2H),2.36–2.23(m,4H),1.92–1.78(m,2H) ,1.76–1.63(m,2H); 13 C NMR (101MHz, CDCl 3 )δ=135.42, 122.53, 109.41, 86.82, 52.11, 34.29, 33.56, 29.47.

Embodiment 2

[0056] The preparation of embodiment 2 azacyclic carbene iridium complex 1b:

[0057]

[0058] Under nitrogen, the cyclooctadiene ligand product 1a (0.26 g) was dissolved in dichloromethane (10 mL), and carbon monoxide gas was continuously passed through at room temperature for 1 h. The completeness of the reaction was checked by TLC. After the reaction was complete, the solvent was concentrated to 2 mL, and enough ether was added to precipitate the product. After filtration and vacuum drying, the product 1b was obtained. Yield: 0.23 g, 95%.

[0059] NMR analysis: 1 H NMR (400MHz, CDCl 3 )δ=7.48–7.40(m,4H),4.13(s,6H); 13 C NMR (101MHz, CDCl 3 )δ=181.27, 167.86, 134.67, 124.08, 110.68, 35.11.

Embodiment 3

[0060] The preparation of embodiment 3 azacyclic carbene iridium complex 2a:

[0061]

[0062] Under nitrogen, in a Schlenk tube, add stir bar, cyclooctadiene iridium chloride dimer (0.16 g), sodium hydride (0.05 g), 1,3-dimethylbenzimidazole tetrafluoroborate (0.23g) and dry tetrahydrofuran (15mL), sealed and stirred overnight at room temperature. The reaction solution was directly passed through the column, and the corresponding 2a was obtained after vacuum drying. Yield: 0.16 g, 48%.

[0063] NMR analysis: 1 H NMR (400MHz, DMSO-d 6 )δ=7.60–7.52(m,4H),7.35–7.27(m,4H),4.18(s,12H),4.04(s,4H),2.40(s,4H),2.08–1.98(m,4H) ; 19 F NMR (376MHz, 298K, DMSO-D 6 )δ=-148.32; 13 C NMR (101MHz, DMSO-d 6 )δ=187.87, 135.42, 123.20, 110.86, 78.18, 35.50, 31.30.

[0064] Mass spectrometry: HR-MS (ESI / TOF) m / z: Calcd.for C 26 h 32 IrN 4 [M-BF 4 ] + 593.2256; found: 593.2261.

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Abstract

The invention specifically relates to a method for preparing lactic acid through selective catalytic conversion of ethylene glycol, belonging to the technical field of fine chemical engineering. The invention provides an azacyclocarbene metal complex catalyst for the selective catalytic conversion of ethylene glycol to produce lactic acid at first. According to the method of the invention, ethylene glycol and methanol are used as raw materials, an alkali metal or alkaline earth metal hydroxide is used as a base, an azacyclocarbene metal complex is used as a catalyst, and a closed reaction is carried out at 100-200 DEG C for 0.5-12 h to prepare lactic acid. Compared with the prior art, the method of the invention has the following advantages: the cheap and easily-available ethylene glycol and methanol are used as substrates; a catalytic oxidation reaction is performed under mild conditions; quantitative lactic acid yield is obtained; reaction conversion efficiency is high; operation iseasy; high-purity lactic acid can be obtained without complicated post-treatment; and the method is suitable for large-scale industrial application.

Description

technical field [0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a method for preparing lactic acid. Background technique [0002] As a common metabolite of organisms, lactic acid is widely distributed in nature. It is recognized as one of the three major organic acids and the smallest chiral molecule in nature. It is a class of industrial products with high added value. At present, the annual production capacity of lactic acid in the world is about 370,000 tons, and the annual production capacity growth rate is about 12%, while the total demand for lactic acid is about 500,000 tons per year, and the annual growth rate is about 16%. Especially in recent years, as a biodegradable bio-based polymer material, polylactic acid has been recognized as an ideal plastic material due to its excellent thermoplasticity and safety. Therefore, the contradiction between supply and demand of lactic acid will become increasingly serious. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/00C07C59/08B01J31/22
CPCB01J31/2273C07C51/00C07C59/08
Inventor 涂涛吴嘉杰郑庆舒
Owner FUDAN UNIV
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