10.10- dichloro-2,8-difluoro

Dibenzo-l,4-oxatelIurine 10,10-Dichloro-2,8-difluoro- E12b, 849 (Ar20 + TeCl4)... 

In another example it has been shown that boron trifluoride is the catalyst of choice to convert dichloromaleic anhydride (9) with sulfur tetrafluoride into 3.4-dichloroperfluoro-2,5-dihy-drofuran (10). In its absence only the formation of a,/i-dichloro->, , -difluoro-y-crotonolactone is observed. 3,4-Dichloroperfluoro-2,5-dihydrothiophene can be prepared in the same manner. 11... 

Iridium Bis-ftripbenylphosphanF carbonyl-dichloro-difluoro-methyl- Xlll/9b, 511 (F2HC-CO-CO- rCl7L, A). 597 (F2CH-CO-Cl + Cll.HrN,)... 

Furthermore, 1-alkyl-1-fluorocyclopropanes were prepared by cycloaddition of alkyl-fluorocarbene, generated from an alkyllithium (usually methyllithium) and dichloro-, difluoro-or chlorodifluoromethane, to alkenes. Due to the many competitive side reactions, H-Li, Hal-Li exchange, alkylation etc., this method has no practical value (for details, see Houben-Weyl, Vol. E19b, pp 1464-1466). 

Dichloro difluoro-methane Eskimon 12 Genetron 12 F-12 Halon 122 Freon 12... 

Trifluoro- Hydrogen Dichloro- Difluoro CH2O CH3CI CH3F... 

Moroni V., Macchi E., Giglioli G., Investigation on thermal stability and corrosion effects of dichloro-difluoro-methane in view of its possible application as working fluid in a power plant. La Termotecnica, vol. 28, 1974, p. 209-221. 

The reaction of dihalocarbenes with isoprene yields exclusively the 1,2- (or 3,4-) addition product, eg, dichlorocarbene CI2C and isoprene react to give l,l-dichloro-2-methyl-2-vinylcyclopropane (63). The evidence for the presence of any 1,4 or much 3,4 addition is inconclusive (64). The cycloaddition reaction of l,l-dichloro-2,2-difluoroethylene to isoprene yields 1,2- and 3,4-cycloaddition products in a ratio of 5.4 1 (65). The main product is l,l-dichloro-2,2-difluoro-3-isopropenylcyclobutane, and the side product is l,l-dichloro-2,2-difluoro-3-methyl-3-vinylcyclobutane. When the dichlorocarbene is generated from CHCl plus aqueous base with a tertiary amine as a phase-transfer catalyst, the addition has a high selectivity that increases (for a series of diolefins) with a decrease in activity (66) (see Catalysis, phase-TRANSFEr). For isoprene, both mono-(l,2-) and diadducts (1,2- and 3,4-) could be obtained in various ratios depending on which amine is used. 

Fig. 2. Preparation of precursors for closure to stmcture (24) at the a bond. (25) = 2,4-dichloro-5- uoroacetophenone [704-10-9], (26) = 4-bromo-2,5-difluoroacetophenone [123942-11 -0], (27) = 2,4-dichloro-5-fluoroben2oic acid [86522-89-6], (28) = 4-bromo-2,5-difluoroben2oic acid [28314-82-1] (29) = ethyl 3-(2,4-dichloro-5-fluorophenyl)-3-oxopropanoate(30) = ethyl 3-(2,5-difluoro-4-bromophenyl)-3-oxopropanoate...

The best known of the hahdes are the trialkyldihalo- and triaryldihaloantimony compounds. The dichloro, dibromo, and diiodo compounds are generally prepared by direct halogenation of the corresponding tertiary stibiaes. The difluoro compounds are obtained by metathasis from the dichloro or dibromo compounds and silver fluoride. The diiodo compounds are the least stable and are difficult to obtain ia a pure state. The tri alkyl- and triaryldichloro- and dibromoantimony compounds are all crystalline soHds which are stable at room temperature that but decompose on heating ... 

Pyrazine, 2,5-dichloro-3,6-difluoro-synthesis, 3, 190-191 Pyrazine, dihydro-, 3, 177 Pyrazine, 1,2-dihydro-oxidation, 3, 178 reduction, 3, 177 Pyrazine, 1,4-dihydro-antiaromaticity, 3, 177-178 synthesis, 3, 177 Pyrazine, 2,3-dihydro-oxidation, 3, 178 Pyrazine, 2,5-dihydro-synthesis, 3, 178 Pyrazine, 3,6-dihydro-synthesis, 3, 184 Pyrazine, 2,5-dihydroxy-oxidation, 3, 175 Pyrazine, 2,3-dimethyl-1,4-dioxide... 

The effect of the substituent group can be seen in the reactions of the following senes of halogenated esters Methyl 2,3 dichloro-3-fluoro-2-methylpropionate and chlorine monofluoride first form methyl 2-chloro-3,3-difluoro-2-methylpro-pionate An additional equivalent of chlorine monofluoride produces methyl 2 methyl-2,3,3-trifluoropropionate (equation 14)... 

The conversion of octachloronaphthalene to octafluoronaphthalene with potassium fluoride and either 18-crown-6, dibenzo-18-crown-6, cis,j>m,cis-dicyclohexano-18-crown-6, cis,anti,cis-dicyclohexano-l 8-crown-6, or irons,syn,trails-dicyclohexano-18-crown-6 demonstrates that 18-crown-6 or dibenzo-18-crown-5 increases the yield and selecuvity and decreases the reaction time [55] Treatment of 3,4-dichloro-],2,5-thiadiazole with potassium fluonde in sulfolane with and without 18-crown-6 present shows that less severe conditions can be used with either 18-crown-6 or dibenzo-18-crown-6 to form 3,4-difluoro-l,2,5-thiadiazole (equation 34)... 

In a definitive study of butadiene s reaction with l,l-dichloro-2,2-difluoio-ethylene, Bartlett concluded that [2+4] adducts of acyclic dienes with fluorinated ethylenes are formed through a mixture of concerted and nonconcerted, diradical pathways [67] The degree of observed [2+4] cycloaddition of fluorinated ethylenes IS related to the relative amounts of transoid and cisoid conformers of the diene, with very considerable (i.e., 30%) Diels-Alder adduct being observed in competition with [2+2] reaction, for example, in the reaction of 1,1 -dichloro-2,2-difluoro-ethylene with cyclopentadiene [9, 68]... 

Chemical Name 2,2-dichloro-1,1-difluoro-1-methoxyethane Common Name 1,1-difluoro-2,2-dichloroethyl methyl ether Structural Formula GHjOCF CHCI ... 

The present method of preparation of 4,4 -dimethyl-l,l -biphenyl is that described by McKillop, Elsom, and Taylor 15 It has the particular advantages of high yield and manipulative simplicity and is, moreover, applicable to the synthesis of a variety of symmetrically substituted biaryls 3,3 - and 4,4 -Disubstituted and 3,3, 4,4 -tetrasubstituted 1,1 -biphenyls are readily piepared, but the reaction fails when applied to the synthesis of 2,2 -disubstituted-l,T biphenyls The submitters have effected the following conversions by the above procedure (starting aromatic bromide, product biphenyl, % yield) bromobenzene, biphenyl, 85,1 -bromo-4-methoxybenzene, 4,4 -dimethoxy-l, 1 -biphenyl, 99, 1 bromo 3 methylbenzene, 3,3 dimethyl-1,l -biphenyl, 85 4-bromo-l,2-dimethylbenzene, 3,3, 4,4 -tetramethyl-l,l -biphenyl, 76, l-bromo-4-chlorobenzene, 4,4 -dichloro-l,l -biphenyl, 73, l-bromo-4-fluorobenzene, 4,4 -difluoro-l,l -biphenyl, 73... 

An extremely pure product results, when difluorochloro methane or difluoro-dichloro methane are used as solvents (79). Dichlorophosphoric acid is a fluid, colourless, very hygroscopic liquid, which is easily soluble in CHCI3, CCI4, Ethanol and Ether (6). In the liquid phase it is stable for some time at room temperature, whereas at 12 Torr there is no sign of decomposition up to 250 °C (6). According to the Raman spectra in the liquid it is dimeric in analogy to the carboxylic acids (20) ... 

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