Potassium hydrogen fluonde

Anhydrous hydrogen fluonde, potassium fluonde, and sodium fluonde have all been used to promote the chlorine-fluonne exchangein tetmchloropyrukizine All three fliionne sources replace the chlonne in position 3 first Both sodium and potassium... 

Difluorododecane is unaffected by sodium methoxide in methanol, but its treatment with potassium tert-butoxide in tetrahydrofuran eliminates hydrogen fluonde stereospecifically rneso and dl compounds give, respectively, ( )- and (2) 6 fluoro 6 dodecene [12] (equation 11)... 

In l-chloro-2-fluoroacenaphthene [58] and in 2,3-dihalo-2,3-dihydrobenzofuran [59, 60], potassium t rt-butoxide eliminates hydrogen fluonde in preference to hydrogen chloride. trares-2-Chloro-3-fluoro-2,3-dihydrobenzofuran loses hydrogen fluoride quantitatively on treatment with sodamide in tert-butyl alcohol [60] (equation 29). 

Preferential elimination of hydrogen fluonde occurs also in highly fluorinated lH -chlorodecafluorocyclohexanes and m 1H,1,2-dichlorononafluorocyclahex-anes [57] It takes place predominantly but not exclusively only m those isomers where hydrogen and fluorine are m antipenplanar conformation When hydrogen and fluorine are in synplanar positions, only hydrogen chlonde is eliminated on treatment with 18 N potassium hydroxide at room temperature for 14 h [57] (equation 28)... 

Dehydrochlorination of bis(tnfluoromethyUhio)acetyl chloride with calcium oxide gives bis(tnfluoromethylthio)ketene [5] (equation 6) Elimination of hydrogen chlonde or hydrogen bromide by means of tetrabutylammonium or potassium fluoride from vinylic chlorides or bromides leads to acetylenes or allenes [d] (equation 7) Addition of dicyclohexyl-18-crown-6 ether raises the yields of potassium fluonde-promoted elimination of hydrogen bromide from (Z)-P-bromo-p-ni-trostyrene m acctonitnle from 0 to 53-71 % In dimethyl formamide, yields increase from 28-35% to 58-68%... 

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