653-35-0Relevant articles and documents
Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
, p. 402 - 415 (2007/10/03)
Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
Reductive transformations of organofluorine compounds: II. Hydrodechlorination of chloropolyfluoroarenes by the action of zinc
Krasnov,Platonov
, p. 1488 - 1499 (2007/10/03)
Polyfluoroarenes containing chlorine atoms in the aromatic ring and/or in the benzylic position undergo hydrodechlorination by the action of zinc in aqueous dimethylformamide. The use of Zn/Cu and addition of salts (NaCl, Na2SO4, NH4Cl) favor reductive dechlorination of the Carom - Cl bond. Polyfluorobenzotrichlorides react with excess zinc to give the corresponding CH3-substituted derivatives, otherwise CH2Cl- and CHCl2-containing compounds are formed. The reduction of C6F5CCl3 and C6F5CH2Cl with zinc in the presence of copper provides lower yields of the hydrodechlorination products and leads to formation of 1,2-bis(pentafluorophenyl)ethane.
UNUSUAL REACTIVITY OF PENTAFLUOROBENZYL AROMATIC ETHERS UNDER FRIEDEL-CRAFTS REACTION CONDITIONS
Xu, Linxiao,Giese, Roger W.
, p. 3829 - 3832 (2007/10/02)
A pentafluorobenzyl (PFBz) ether of 2,6-dimethylphenol undergoes a PFBz rearrangement, which appears to be intermolecular, yielding a 2:3 ratio of meta to para migration.Only ether bond cleavage takes place in a corresponding PFBz ether of 2,6-difluorophenol.Both sets of products are unusual, and it is suggested that they are both due to high reactivity of the PFBz-oxy moiety with the AlCl3 catalyst.
