Dimethyl Sulfoxide → 1,3-Difluorobenzene

HRID 257708Notes

Reaction equation

HRID 257708 reaction equation
[F:1][B-](F)(F)F.[C:6]1([N+]#N)[CH:11]=[CH:10][CH:9]=[C:8]([N+:12]#N)[CH:7]=1.[F:16][B-](F)(F)F.CS(C)=O.[FH:25]>>[F:16][C:6]1[CH:7]=[C:8]([CH:9]=[CH:10][CH:11]=1)[NH2:12].[F-:1].[NH4+:12].[F:25][C:6]1[CH:11]=[CH:10][CH:9]=[C:8]([F:16])[CH:7]=1

Participants

6

Reactant 3

HCID 679Dimethyl SulfoxideHCID 14917Hydrofluoric AcidHCID 15304907HCID 15304907, compound

Product 3

HCID 97411,3-DifluorobenzeneHCID 97423-FluoroanilineHCID 25516Ammonium fluoride

Procedure

Fluorobenzenes have hitherto been prepared from the corresponding substituted anilines by diazotization and subsequent replacement of the diazo group by fluorine. Thus the preparation of fluorobenzene by diazotization of aniline hydrochloride, conversion of the resulting benzenediazonium chloride into the tetrafluoroborate and subsequent heating has long been known (G. Balz and G. Schiemann, Ber. 60 (1927) 1188; D. T. Flood, Org. Synth. Coll. Vol II (1943) 295). In addition, the preparation of fluorobenzene by diazotization of aniline in anhydrous hydrogen fluoride at 0° C. with subsequent decomposition of the resulting benzenediazonium fluoride at 20° C. is also described (Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed. Vol. 10, p. 908). 1,3-Difluorobenzene could be obtained analogously in a 31% yield, relative to m-phenylenediamine as starting compound, by heating benzene-1,3-bis-diazonium tetrafluoroborate (G. Schiemann and R. Pillarsky, Ber. 62 (1929) 3035-3043, especially 3029). The diazotization of 3-fluoroaniline in anhydrous hydrogen fluoride in the presence of either ammonium fluoride or tertiary amines or dimethyl sulfoxide produced in each case 1,3-difluorobenzene in a yield of 46 to 73% (U.S. Pat. No. 4,075,252 and U.S. Pat. No. 4,096,196).

Sources & evidence

ORD record
ord-fdbc5284bd2646b19908ea061776c4ed
Source dataset
uspto-grants-1993_11
Patent number
US05264094

Reaction notes

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