3,4-Difluorobenzonitrile synthesis

10synthesis methods

Product Name:3,4-Difluorobenzonitrile
CAS Number:64248-62-0
Molecular formula:C7H3F2N
Molecular Weight:139.1

The preparation of 3,4-Difluorobenzonitrile is as follows:To the dry reactor was added 289.6 kg (1.843 kmoles) of 3,4-difluorobenzamide and 800 kg of dichloroethane solution, 241.2 kg (2.02 kmoles) of dichlorosulfoxide and catalyst DMF I.5 And the reaction was carried out at 50 ° C for 5 hours with stirring. After the reaction was complete, the reaction solution was poured into ice water with stirring and the mixture was separated to obtain a crude product having a qualitative content of 96% of 3,4-difluorobenzonitrile 259.1 kg (1.788 kmoles) in 97% yield. The crude product was distilled to give a qualitative content of 99% of 3,4,8-difluorobenzonitrile 248.6 kg (1.77 kmoles) and a distillation yield of 99%.

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Yield:64248-62-0 204 g

Reaction Conditions:

with potassium fluoride in cyclohexane;water at 180; for 5 h;Industrial scale;Temperature;

Steps:

5 In the present invention, the reaction after rectification mother liquor (including catalyst) directly as the next batch of feed used as follows:

In a 2000ml reactor with a stirrer, reflux manifold, thermometer was added 300g3,4_ dichlorobenzonitrile, 920g Example 4 rectification mother liquor (catalyst, a small amount of intermediate), 120g of cyclohexane, Warmed to 120 ° C, reflux separation.After the water separator to be anhydrous split into 300g spray-dried potassium fluoride, bis - (N- (dimethylamino) methylene) - chloride imide salt 5g, warmed to 130 ° C, reflux Water reaction 3h, to give the intermediate 3-chloro-4-fluorobenzonitrile, continue to heat up to 180 ° C, the reaction 5h end.The reaction solution was filtered to remove salts, the filter cake was washed three times with toluene, the filtrate was vacuum-distilled,In the vacuum control 0.08 ~ 0.09MPa,The top of the tower collected 90-105 ° C of the fraction 204g, GC purity 99.3%, yield 85%.

References:

CN103539699,2017,B Location in patent:Paragraph 0040-0043

6574-99-8 Synthesis