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In chemistry, a sulfonyl halide consists of a sulfonyl (>S(=O) 2) group singly bonded to a halogen atom. They have the general formula RSO 2 X , where X is a halogen. The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides , all four types being well known.
Sulfuryl fluoride (also spelled sulphuryl fluoride) is an inorganic compound with the formula SO 2 F 2. It is an easily condensed gas and has properties more similar to sulfur hexafluoride than sulfuryl chloride , being resistant to hydrolysis even up to 150 °C. [ 3 ]
The sulfonyl functional group (RS(O) 2 R') has become an important electron-withdrawing group for modern organic chemistry. α-Sulfonyl carbanions may be used as nucleophiles in alkylation reactions, Michael-type additions, and other processes. [3] After having served their synthetic purpose, sulfonyl groups are often removed.
For small scale reactions, SF 4 can be inconvenient since it is a gas and stainless steel reaction vessels are required. Many transformations require elevated temperatures. The reaction generates hydrogen fluoride. These concerns have led to interest in alternative fluorinating reagents. [1]
Trimethylsilyl enol ethers react with NfF in the presence of a substoichiometric fluoride source at 0 °C to ambient temperature to give alkenyl nonaflates in moderate to good yields. Dried tetra-n-butylammonium fluoride was the preferred fluoride source in one study, [6] but CsF has been used in difficult cases with excellent results. [7]
Reactions of elemental fluorine with metals require diverse conditions that depend on the metal. Often, the metal (such as aluminium, iron, or copper) must be powdered because many metals passivate by forming protective layers of the metal fluoride that resist further fluoridation. [7]
Nafion derivatives are first synthesized by the copolymerization of tetrafluoroethylene (TFE) (the monomer in Teflon) and a derivative of a perfluoro (alkyl vinyl ether) with sulfonyl acid fluoride. The latter reagent can be prepared by the pyrolysis of its respective oxide or carboxylic acid to give the olefinated structure.
Sulfonyl groups can be written as having the general formula R−S(=O) 2 −R′, where there are two double bonds between the sulfur and oxygen. [1]: 53 [2] Sulfonyl groups can be reduced to the sulfide with diisobutylaluminium hydride (DIBALH). Lithium aluminium hydride (LiAlH 4) reduces some but not all sulfones to sulfides. [1]: 1851