Solvent-free thermal dehydration of pentitols on zeolites
Dehydration of D-arabinitol, ribitol, and xylitol at high temperature in the presence of molecular sieves without solvent in an argon atmosphere is described. Products arising after the dehydration-cyclization (cyclodehydration) reaction with retention or inversion of the configuration of asymmetric carbon atoms, were observed. Complete analytical separations of exhaustively O-acetylated reaction products were achieved by means of GC. The chemical structures of the compounds obtained were assigned using co-injection with standards. Copyright
Kurszewska, Maria,Skorupowa, Eugenia,Madaj, Janusz,Wisniewski, Andrzej
p. 169 - 177
(2007/10/03)
ISOMERISATION DURING DEHYDRATION OF PENTITOLS IN ACID MEDIA
The products of dehydration of pentitols in aqueous sulfuric acid have been studied by g.l.c.-m.s.Four isomeric 1,4-anhydropentitols were formed from D-arabinitol, but only two from xylitol and ribitol.The number of products could only be explained by assuming inversion of configuration at C-2 or C-4 during 1,4- or 2,5-cyclisation reactions.No product which involved inversion of configuration at C-3 was observed.Various mechanisms of isomerisation are considered.
Wisniewski, Andrzej,Szafranek, Janusz,Sokolowski, Janusz
p. 229 - 234
(2007/10/02)
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