Reaction with sulfur fluorides

Carbon disulfide gives an essentially quantitative yield of carbon tetrafluoride (4) and sulfur on reaction with sulfur tetrafluoride at 450 C in the presence of arsenic(III) fluoride as catalyst. At lower temperatures and with boron trifluoride as catalyst, bis(trifluoromethyl) polysulfides 5 and 6 are formed.205... 

Nonmeta.ls, Sulfur reacts with fluorine to yield the remarkably stable sulfur hexafluoride, SF. Operating conditions must be controlled because a mixture of the lower fluorides such as disulfur difluoride [13709-35-8] 2 2 disulfur decafluoride [5714-22-7] 2 10 sulfur tetrafluoride [7783-60-0] SF4, may also be formed. When this reaction is carried out between 310 and 340°C, SF is primarily obtained and essentially no SF and only trace amounts of lower fluorides. Below 300°C, and preferably at ca 275°C, SF is the primary product. At 450—500°C, a mixture comprising ca 50% SF and the lower sulfur fluorides is formed (see Fluorine compounds, inorganic-sulfur). 

Halogen fluorides react with sulfur, selenium, teUurium, phosphoms, sHicon, and boron at room temperature to form the corresponding fluorides. Slight warming may be needed to initiate the reactions (4) which, once started, proceed rapidly to completion accompanied by heat and light. The lack of protective film formation aHows complete reaction. 

Ammonium fluorosulfate is produced from ammonium fluoride by reaction with sulfur trioxide, oleum, or potassium pyrosulfate, 1 2820 (48). Solutions of ammonium fluorosulfate show Htfle evidence of hydrolysis and the salt may be recrystallized from hot water. Ammonium fluorosulfate absorbs anhydrous ammonia to form a series of Hquid amines that contain 2.5—6 moles of ammonia per mole of salt (77). 

Fluoride ion attacks the sulfur atom in 2,3-diphenylthiirene 1,1-dioxide to give ck-1,2-diphenylethylenesulfonyl fluoride (23%) and diphenylacetylene (35%). Bromide or iodide ion does not react (80JOC2604). Treatment of S-alkylthiirenium salts with chloride ion gives products of carbon attack, but the possibility of sulfur attack followed by addition of the sulfenyl chloride so produced to the alkyne has not been excluded (79MI50600). In fact the methanesulfenyl chloride formed from l-methyl-2,3-di- -butylthiirenium tetrafluoroborate has been trapped by reaction with 2-butyne. A sulfurane intermediate may be indicated by NMR experiments in liquid sulfur dioxide. 

Replacement of ketones with fluorine by reaction with sulfur tetrafluoride-hy-drogen fluoride, 471... 

Perfluoro-y-butyrolactone can be prepared from 1,4 diiodoperfluorobutane by reaction with turning sulfuric acid (oleum) [7S] (equation 19) The yield depends on the concentration of sulfur trioxide One of the by-products, 4-iodoperfluo-robutyryl fluoride, can be recycled to increase the overall yield of the lactone Pure sulfur trioxide generates only perfluorotetrahydrofuran, the lodo acyl fluoride, and perfluorosuccmyl fluoride... 

In contrast to other acids, anhydrous hydrogen fluoride does not cause hydroly SIS and decarboxylation of the malonic acid residues in these reactions [5]. It is a good reagent for the cyclization of a-benzamidoacetophenones to 2,5 diphenyl-oxazoles [6] (equation 7) The same reaction with concentrated sulfuric acid gives cyclic product with only a 12% yield [6]... 

Thionyl fluoride, as by-product in sulfur tetrafluoride reactions, 41, 105 toxidty of, 41,105 Thiophene-2-OL, 43, 55 2(5H)-Thiophenone, 43, 55 Thiosemicarbazide, in synthesis of 1,2,4 triazole, 40, 99 reaction with formic acid to yield l-formyl-3-thiosemicarbazide, 40,99... 

There are a number of other methods to prepare crude sulfane oils, e.g., from hquid H2S and elemental chlorine or bromine [10] or by reaction of H2S with sulfur fluorides [10] or sulfur chlorides [20] but these processes are of httle practical importance. 

A series of reactions with gases have been selected for the rapid quantification of many of the major products from the oxidation of polyolefins. Infrared spectroscopy is used to measure absorptions after gas treatments. The gases used and the groups quantified include phosgene to convert alcohols and hydroperoxides to chloroformates, diazomethane to convert acids and peracids to their respective methyl esters, sulfur tetrafluoride to convert acids to acid fluorides and nitric oxide to convert alcohols and hydroperoxides to nitrites and nitrates respectively. 

Reaction to give tetrafluorooxathietane 2,2-dioxide (tetrafluoroethane sultone) had been used industrially and uneventfully, but reaction with excess sulfur trioxide may cause explosive decomposition to carbonyl fluoride and sulfur dioxide [1]. An incident involving the same explosion hazard was reported 11 years later [2], Use of inert gas to prevent explosion has been patented [3],... 

Treatment of l,3-diisopropyl-4,5-dimethylimidazol-2-ylidene with SC12 and S0C12 resulted in 87 and 88, respectively (67). Complex 87 can be converted into the corresponding fluoride (89) via reaction with AgF. Surprisingly, however, reduction of the sulfur center was ob-... 

Nitration of the amine (139) with mixed acid yields the energetic nitramine (140). The same reaction with sodium nitrite in sulfuric acid, or with nitrosyl fluoride in methylene chloride, yields the nitrosamine (141), which is also an energetic high explosive. ... 

Unlike boron fluoride, titanium tetrachloride does not catalyze the liquid phase polymerization of isobutylene under anhydrous conditions (Plesch et al., 83). The addition of titanium tetrachloride to a solution of the olefin in hexane at —80° failed to cause any reaction. Instantaneous polymerization occurred when moist air was added. Oxygen, nitrogen, carbon dioxide, and hydrogen chloride had no promoting effect. Ammonia and sulfur dioxide combined with the catalyst if these were added in small quantity only, subsequent addition of moist air permitted the polymerization to occur. Ethyl alcohol and ethyl ether, on the other hand, prevented the polymerization even on subsequent addition of moist air. They may be regarded as true poisons. 

A detailed study of the conversion of 3,4-dichloro-l,2,5-thiadiazole into 3,4-diamino-l,2,5-thia-diazole has been carried out <76JHC13>. Reaction with lithium or sodium amide produces only 4% of the diamine together with cyano-containing by-products, a consequence of direct attack on sulfur. Use of a less powerful nucleophile, ammonia or potassium phthalimide, resulted in an increased attack on carbon and produced the diamine in 24% and 66% yields, respectively. Secondary amines, e.g. morpholine <76JOC3l2l> and dimethylamine <72JMC315>, produce the normal displacement products. The reaction of dichlorothiadiazole with potassium fluoride in sulfolane gives a mixture of 3-chloro-4-fluoro and 3,4-difluoro-l,2,5-thiadiazole <82CB2135>. 

Reaction with concentrated sulfuric acid yields hydrogen fluoride and calcium sulfate ... 

Reaction with phosphorus trichloride yields phosphorus trifluoride and with phosphoryl fluoride and sulfur trioxide, the product is phosphorus penta-fluoride ... 

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