TY  - JOUR
A1  - Bock, Hans
A1  - Wolf, Hans Peter
T1  - Oberflächen-Reaktionen, 9 [1]. Dehydrohalogenierungen von Halogenkohlenwasserstoffen an Raney-Nickel [2—4]
T1  - Surface reactions, 9 [1]. Dehydrohalogenation of halohydrocarbons at Raney nickel [2—4]
T2  - Zeitschrift für Naturforschung, B
N2  - Raney nickel, a highly reactive and air-sensitive solid, if prepared and investigated under oxygen-free conditions, exhibits interesting catalytic properties. Using photoelectron spectroscopy for real-time gas analysis in a flow reactor, the following results are obtained with alkyl and acylhalides: Dehydrohalogenation temperatures are lowered relative to thermal HHal elimination up to 350 K. Monochloro and bromo propanes and butenes yield propene and butadiene, respectively. 1,1-Dichloro ethane or 1,1-dibromo propane only split off one HHal and form chloroethene or 1-bromopropene-2. HCl elimination from 2-methyl propionic acid chloride, expectedly, produces dimethyl ketene. Most interesting, however, is the ring opening of monobromo cyclobutane to 1-bromo-butene-3, observed already at room temperature, which strongly suggests the intermediate formation of a chemisorbed surface carbene at Raney nickel. The formation of hexadiene-1,5 as a by-product in the HCl elimination of 1-chloropropane, i. e. a surface carbene dimer, indicates their presence also in other dehydrohalogenations heterogeneously catalyzed by Raney nickel.
Raney nickel, a highly reactive and air-sensitive solid, if prepared and investigated under oxygen-free conditions, exhibits interesting catalytic properties. Using photoelectron spectroscopy for real-time gas analysis in a flow reactor, the following results are obtained with alkyl and acylhalides: Dehydrohalogenation temperatures are lowered relative to thermal HHal elimination up to 350 K. Monochloro and bromo propanes and butenes yield propene and butadiene, respectively. 1,1-Dichloro ethane or 1,1-dibromo propane only split off one HHal and form chloroethene or l-brom opropene-2. HCl elim ination from 2-methyl propionic acid chloride, expectedly, produces dimethyl ketene. Most interesting, how ever, is the ring opening of monobromo cyclobutane to 1-brom o-butene-3, observed already at room temperature, which strongly suggests the intermediate formation of a chem isorbed surface carbene at Raney nickel. The formation of hexadiene-1,5 as a by-product in the HCl elim ination of 1-chloropropane, i.e. a surface carbene dimer, indicates their presence also in other dehydrohalogenations heterogeneously catalyzed by Raney nickel.
Y1  - 2014
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/71409
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-714097
SN  - 1865-7117
SN  - 0932-0776
VL  - 44.1989
IS  - 6
SP  - 699
EP  - 713
PB  - Verlag der Zeitschrift für Naturforschung
CY  - Tübingen
ER  -