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Preparation method and application of perfluoroalkyl diazomethane

A perfluoroalkyl and diazomethane technology, which is applied in the preparation of halogenated hydrocarbons, sulfonamides, chemical instruments and methods, etc., can solve the problems of cumbersome operation, explosion hazard, and inapplicability, and achieve mild reaction conditions, The effect of wide substrate range and easy operation

Active Publication Date: 2018-02-27
NORTHEAST NORMAL UNIVERSITY
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

The trifluoroethylamine hydrochloride oxidation method is currently the only method for preparing trifluoromethyldiazomethane, but it has the following disadvantages: 1) It is not suitable for reactants sensitive to acids and oxidants; 2) Trifluoromethyldiazomethane Methane is highly explosive, and excessive accumulation is prone to explosion hazards; 3) The operation is cumbersome, and sodium nitrite aqueous solution needs to be slowly added dropwise to the reaction system to control the rate of release of trifluoromethyldiazomethane
However, in order to avoid the accumulation of trifluoromethyldiazomethane in this method, it is necessary to use a syringe pump to slowly add sodium nitrite dropwise, which is not conducive to further industrial production
At the same time, the reaction needs to be carried out under the conditions of strong acid and strong oxidant, and the types of functional groups are greatly limited.

Method used

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  • Preparation method and application of perfluoroalkyl diazomethane
  • Preparation method and application of perfluoroalkyl diazomethane
  • Preparation method and application of perfluoroalkyl diazomethane

Examples

Experimental program
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Effect test

Embodiment 1 3

[0048] The preparation of embodiment 1 trifluoroacetaldehyde benzenesulfonylhydrazone 4a

[0049] The reaction formula of steps (1)~(2) is as follows:

[0050] ;

[0051] (1) Under nitrogen, add o-nitrobenzenesulfonylhydrazide 2a (10.9g, 50mmol) and 200mL ethyl acetate into a 250mL reaction flask, stir until dissolved, cool down to 0°C in an ice-water bath, add 10 drops of concentrated Sulfuric acid, add trifluoroacetaldehyde hydrate 1a (8.7g, 75mmol), react at 0°C until TLC monitoring shows that o-nitrobenzenesulfonyl hydrazide 2a disappears; add 50mL of 10% saline solution, separate the liquid, and wash the organic phase with saturated Washed twice with aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, suction filtered, and the filtrate was dropped into 1000mL of n-hexane, a white solid was gradually precipitated, filtered, and dried in vacuo to obtain a white solid 3a (15.1g, yield 96%), without Purification, the next reaction directly.

[0052...

Embodiment 2

[0054] Example 2 Preparation of trifluoroacetaldehyde benzenesulfonylhydrazone 4b

[0055] The reaction formula of steps (1)~(2) is as follows:

[0056]

[0057] (1) Under nitrogen, add o-trifluoromethylbenzenesulfonylhydrazide 2b (4.8 g, 20 mmol) and 40 mL of 1,2-dichloroethane into a 250 mL reaction flask, stir until dissolved, and cool down in an ice-water bath To 0°C, add 10 drops of glacial acetic acid dropwise, add trifluoroacetaldehyde hydrate 1a (3.5g, 30mmol), react at 0°C until o-trifluoromethylbenzenesulfonyl hydrazide 2b disappears, add 10% salt 25 mL of water, separated, the organic phase was washed twice with saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, filtered with suction, dropped into 300 mL of n-hexane, a white solid gradually precipitated, filtered, and dried in vacuo to obtain a white solid 3b (15.1 g, yield 96%), without purification, directly to the next step reaction.

[0058] (2) Under the condition of nitrog...

Embodiment 3

[0060] Example 3 Preparation of pentafluoropropionaldehyde benzenesulfonylhydrazone 4c

[0061] The reaction formula of steps (1)~(2) is as follows:

[0062]

[0063] (1) Under nitrogen, add o-trifluoromethylbenzenesulfonylhydrazide 2b (4.8 g, 20 mmol) and 40 mL of 1,2-dichloroethane into a 250 mL reaction flask, stir until dissolved, and place in an ice-water bath Cool down to 0°C, add 10 drops of glacial acetic acid dropwise, add pentafluoropropionaldehyde hydrate 1b (5.0 g, 30 mmol), react at 0°C until o-trifluoromethylbenzenesulfonyl hydrazide 2b disappears, add 10 25 mL of saline solution, separated, the organic phase was washed twice with saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, filtered with suction, the filtrate was dropped into 200 mL of n-hexane, white solids were gradually precipitated, filtered, and vacuum-dried to obtain White solid 3c (7.0 g, yield 90%) was directly used in the next step without purification.

[006...

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Abstract

The invention discloses a method for mildly generating perfluoroalkyl diazomethane in situ. By utilizing the method, through starting with perfluoroalkyl aldehyde or a hydrate thereof, which is low inprice and is easily obtained, a substitution reaction is generated with a derivative of benzenesulfonyl hydrazide under the catalysis of protonic acid; the dehydration is carried out in the presenceof a dehydrating agent to obtain a perfluoroalkyl diazomethane precursor; the perfluoroalkyl diazomethane is slowly released in an alkaline condition. Further, by utilizing the preparation method of the perfluoroalkyl diazomethane, a novel method for synthesizing trifluoromethyl cyclopropane in a two-phase system through a one-pot method without carrying out separation is invented. By using the method, the separation of trifluoromethyl diazomethane which has toxicity and explosion danger is avoided; the method has the advantages of mild reaction condition, wide substrate range and good functional-group tolerance, and meanwhile, the method has the advantages of being simple and convenient to operate and needing no special equipment to slowly dropwise add, can be used for safely and efficiently synthesizing the trifluoromethyl cyclopropane, whose order of magnitude is 1 to 100 grams, in a laboratory and has further industrialized application potential.

Description

technical field [0001] The invention relates to the field of organic chemical synthesis, in particular to a preparation method of perfluoroalkyldiazomethane and its application in one-pot synthesis of trifluoromethylcyclopropane. technical background [0002] Fluorine-containing organic molecules often exhibit unique properties and are widely used in the fields of medicine, pesticides and materials. Perfluoroalkyl groups have strong electron-withdrawing properties, lipophilicity, and relatively stable C-F bonds. The introduction of perfluoroalkyl groups into organic compounds can significantly change the physical, chemical and biological properties of the compounds. According to statistics, more than 20% of drugs and agricultural chemicals contain at least one fluorine atom, especially many drugs contain trifluoromethyl functional group ( Nature 2011, 473 , 470; Chem. Rev. 2014 ， 114， 2432). Therefore, it is of great significance to develop new perfluoroalkylation re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C245/14C07C303/40C07C311/49C07C22/08C07C17/00
CPCC07C17/00C07C245/14C07C303/40C07C311/49C07C22/08
Inventor 毕锡和刘兆洪刘宾宾张欣宇
Owner NORTHEAST NORMAL UNIVERSITY
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