ChemicalBook CAS DataBase List 3,5-difluorobenzophenone

3,5-difluorobenzophenone synthesis

10synthesis methods

Product Name:3,5-difluorobenzophenone
CAS Number:179113-89-4
Molecular formula:C13H8F2O
Molecular Weight:218.2

Synthesis of 3,5-Difluorobenzophenone: Prior to acylations, 3,5-difluorobenzoic acid was reacted with freshly distilled thionyl chloride and catalytic amounts of DMF(2 drops). After two hours at 55 °C, the excess thionyl chloride was distilled between 75 and 77 °C. The acid halide was then fractionally distilled at 174 °C, and recovery was generally around 75%. To a 50 mL round bottom flask, equipped with a gas inlet, addition funnel, condenser, and drying tube, were added 3.01 g (22.6 mmol) of AlCl3. A mixture of 3.62 g (20.5 mmol) 3,5-difluorobenzoyl chloride and 8.01 g (102.5 mmol) benzene was added dropwise to the AlCl3. The reaction mixture was stirred for 4 hours, before heating to 75 °C. After 16 hours the reaction mixture was quenched by pouring into acidic ice water, followed by addition of 300 mL of chloroform, and transferring to a separatory funnel. The layers were separated and the organic layer was washed with 5 wt. % bicarbonate, distilled water, and then dried with MgSO4 and the solvents were removed, via rotary evaporation, leaving an off-white solid. The crude material was recrystallized from aqueous ethanol to afford (3.00 g, 67 %) of a crystalline white solid with a m.p. 58-59 °C (lit.21 m.p. 57-58 °C); 1H NMR (300 MHz, CDCl3, δ) 7.04 (tt, 1H, J = 8.4, 2.4 Hz), 7.31 (m, 2H), 7.51 (m, 2H), 7.63 (tt, 1H, J = 7.5, 1.2 Hz), 7.78 (m, 2H)

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Yield: 75%

Reaction Conditions:

with copper(l) iodide;silver carbonate in N,N-dimethyl-formamide at 120; for 24 h;

Steps:

General procedure for the synthesis of Biaryl ketones from thiolester
General procedure: Thiolester (0.25 mmol), arylboronic acids (0.375 mmol), CuI (20 mol%, 10 mg), Ag2CO3 (5 mol%, 4 mg) and DMF (3 ml) were taken in a 25 ml round bottomed flask. The reaction mixture was heated at 120 C for 8-24 h. The reaction monitored using TLC. Upon completion, the reaction mixture was diluted with water and extracted with DCM (3x10 ml). The combined organic layer was dried over anhydrous sodium sulphate and concentrated under reduced pressure. The resulting ketone was purified was purified using silica gel column chromatography (EtOAc and petroleum ether 60-80 C).

References:

Ghosh, Prasanjit;Ganguly, Bhaskar;Das, Sajal;Perl, Eliyahu [Tetrahedron Letters,2017,vol. 58,# 28,p. 2751 - 2756]

108-86-1 Synthesis