Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfur containing
Patent
1997-03-28
1998-04-21
Ivy, C. Warren
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfur containing
C07C38100
Patent
active
057419353
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the preparation of fluorinated organic compounds, in particular organic sulphur pentafluorides.
Organic sulphur pentafluorides such as arylsulphur pentafluorides are potentially important compounds useful, for example, in the manufacture of agricultural and pharmaceutical chemicals and polymer products. Convenient routes to these stable compounds are not generally available in the prior art because of the difficulty of making these compounds. Several examples of fluorination have been reported using silver (II) fluoride which is an expensive reagent. In many cases the yield has been very low. (Ref W A Sheppard J.A.C.S. 84 3058 (1962) Ibid 84 3064 (1962).
According to the present invention there is provided a method for the preparation of a pentafluoride having a formula (1) as follows: into the compound of formula (1) a disulphide of formula (2) as follows: solvent of the compound of formula (2) with elemental fluorine.
The groups R.sup.1 and R.sup.2 are independently selected from aryl, heteroaryl and aliphatic and alicyclic groups. Preferably R.sup.1 and R.sup.2 are the same although they may also be different groups where R.sup.1 and R.sup.2 are different, the product R.sup.1 SF.sub.5 is present as a mixture with the corresponding product R.sup.2 SF.sub.5.
Where R.sup.1 and/or R.sup.2 is aryl it may comprise an optionally substituted phenyl, biphenyl or naphthyl group.
Where R.sup.1 and/or R.sup.2 is heteroaryl it may comprise an optionally substituted mono- or bicyclic group containing one or more heteroatoms selected from nitrogen and oxygen. For example, R.sup.1 and/or R.sup.2 may be pyridyl, pyrimidyl or bipyridyl, quinoline and isoquinoline.
Where R.sup.1 and/or R.sup.2 is aliphatic or alicyclic it may be selected from optionally substituted alkyl or cycloalkyl groups eg having from 1 to 10 carbon atoms, especially 1 to 6 carbon atoms.
Where the group R.sup.1 or R.sup.2 is a substituted aryl group it may include from one to five substituents, eg especially one or two substituents, which are less reactive than the disulphide toward fluorine and which do not react with the organic sulphur trifluorides (formed during the conversion of compounds of formula (2) to those of formula (1)). Such substituent(s) may be selected from cyano, nitro, halogen, alkyl, fluoroalkyl, aryl, alkoxy and cycloalkyl.
A preferred form of the compound of formula (2) for use in the method of the present invention is Ar.sup.1 --S--S--Ar.sup.1 wherein the Ar.sup.1 groups are the same. Each Ar.sup.1 may be a mono- or hi-cyclic aromatic ring optionally containing one or more substituents or heteroatoms. Ar.sup.1 and Ar.sup.2 may for example both be selected from phenyl, 4-nitrophenyl, 4cyanophenyl, 4-halophenyl.
The compound of formula (2) may in some examples be obtained by oxidation of a thiol of formula (3) as follows:
The thiol of formula (3) may be converted into the disulphide of formula (2) by use of fluorine in the fluorination step. Thus, the thiol of formula (3) may be used as the starting material in a reaction in which the compound of formula (2) is produced during reaction with elemental fluorine.
In the process according to the present invention, the compound of formula (2) may be contained in an inert solvent which is substantially anhydrous and aprotic. Suitable solvents include organic liquids which do not contain compounds having hydroxyl or carbonyl groups, eg solvents selected from acetonitrile, chlorinated or fluorinated hydrocarbons or perftuorocarbons or mixtures of them.
The process according to the present invention may be carried out by passing fluorine gas into a slurry or solution of the compound of formula (2) in the solvent medium. The reaction may be carried out by passing the fluorine into a vessel in which the slurry or solution is present or, alternatively, a flowstream of the slurry or solution may be contacted by the fluorine gas in co- or counter-current fashion.
The process according to the present invention may be carried out at a temperature in the range -40
REFERENCES:
patent: 522070 (1894-06-01), St. Clair
patent: 3102903 (1963-09-01), Coffman
patent: 3117158 (1964-01-01), Sheppard
"Novel Synthesis of Unusual Classes of Fluorocarbon Organosulfur Compounds Using Elemental Fluorine as a Reagent" by Huang ett al., Inorganic Chemistry, vol. 30, No. 4, Feb. 20, 1991, pp. 789-794.
"Sulfur Cyanide Pentafluoride SF.sub.5 CN" by Losking et al., Angewandte Chemie. International Edition, vol. 28, No. 9, Sep. 1989, pp. 1255-1256.
"Arylsulfur Pentafluorides" by Sheppard, Journal of the American Chemical Society, vol. 84, No. 16, Aug. 20, 1962, pp. 3064-3072.
Bowden Roy D.
Greenhall Martin P.
Moilliet John S.
Thomson Julie
British Nuclear Fuels PLC
Ivy C. Warren
Vollano Jean F.
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