3-Bromo-3,3-difluoropropene synthesis
- Product Name:3-Bromo-3,3-difluoropropene
- CAS Number:420-90-6
- Molecular formula:C3H3BrF2
- Molecular Weight:156.96
Yield:-
Reaction Conditions:
with potassium hydroxide in water at 90 - 110; for 3 h;
Steps:
1
Example 1; This Example shows the preparation of the allyl halide, CH2CHCF2Br. CF2Br2 (400 g) and (PhCO2)2 (10 g) were charged into a 600 mL autoclave, which was previously purged with N2 for 30 min. The autoclave was closed and filled with CH2CH2 at 100 psi pressure while stirring. The autoclave was heated to 65° C. and then the heating was switched off. The highest inner temperature was 110° C., then the heating control was set at 90° C. and CH2CH2 pressure was controlled at 200 psi and so maintained for about 24 hours. The autoclave was then allowed to return to room temperature and excess CH2CH2 was released. From the fractional distillation of the product, excess CF2Br2 (230 g) was stripped off and then 120 g BrCH2CH2CF2Br was collected (b.p. 73° C., purity (GC) 97%). The dehydrobromination was carried out in a 250 mL three neck flask equipped with an addition funnel and a Claison type distillation head. The distillation receiver was cooled in ice. A solution of KOH (120 g) in water (100 ml) was added in the flask and the flask was heated in a 90-100° C. oil bath. BrCH2CH2CF2Br (90 g) was added dropwise from the addition funnel in the flask for about 60 minutes with vigorous stirring. After the addition the reaction was continued at 100-110° C. for 2 hours. 60 g crude product was collected, which was then dried with Na2SO4. After fractional distillation, 57 g of product was collected, having a ratio of CH2CHCF2Br to CF2CHCH2Br of 90:10.
References:
Honeywell International Inc. US2007/161827, 2007, A1 Location in patent:Page/Page column 3
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