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Base-free transfer hydrogenation of menthone by sub- and supercritical alcohols. / Philippov, Alexey A.; Chibiryaev, Andrey M.; Martyanov, Oleg N.
In: Journal of Supercritical Fluids, Vol. 145, 01.03.2019, p. 162-168.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Base-free transfer hydrogenation of menthone by sub- and supercritical alcohols
AU - Philippov, Alexey A.
AU - Chibiryaev, Andrey M.
AU - Martyanov, Oleg N.
N1 - Publisher Copyright: © 2018 Elsevier B.V.
PY - 2019/3/1
Y1 - 2019/3/1
N2 - The base-free transfer hydrogenation (THR) of menthone with six aliphatic alcohols as hydrogen source has been developed under sub- and supercritical conditions. Under sc conditions (at 350 °C and 78–210 atm) without any catalyst, all alcohols demonstrated the similar H-donor activity, which was high enough. The menthone conversion was about 64 ± 5% for 5 h of the reaction, whereas the selectivity on menthol reached 92–99% for all alcohols except MeOH (73%). The non-catalytic THR at 250 °C was very slow and the conversion in the most active 2-PrOH was only 7.0–7.5% for 9 h of the reaction. Under subcritical conditions at 150 °C, the non-catalytic menthone reduction was negligible in all alcohols. But in secondary 2-PrOH and 2-BuOH, the base-free THR catalyzed by Raney® nickel results in excellent conversion and selectivity of menthol at 150 °C, whereas no conversion of menthone was observed in primary alcohols under the same reaction conditions. A quasi-equilibrium of isomeric menthone/isomenthone mixture reached via enolization was evaluated under sub- and supercritical conditions and the Gibbs energies of the isomerization in each alcohol were calculated.
AB - The base-free transfer hydrogenation (THR) of menthone with six aliphatic alcohols as hydrogen source has been developed under sub- and supercritical conditions. Under sc conditions (at 350 °C and 78–210 atm) without any catalyst, all alcohols demonstrated the similar H-donor activity, which was high enough. The menthone conversion was about 64 ± 5% for 5 h of the reaction, whereas the selectivity on menthol reached 92–99% for all alcohols except MeOH (73%). The non-catalytic THR at 250 °C was very slow and the conversion in the most active 2-PrOH was only 7.0–7.5% for 9 h of the reaction. Under subcritical conditions at 150 °C, the non-catalytic menthone reduction was negligible in all alcohols. But in secondary 2-PrOH and 2-BuOH, the base-free THR catalyzed by Raney® nickel results in excellent conversion and selectivity of menthol at 150 °C, whereas no conversion of menthone was observed in primary alcohols under the same reaction conditions. A quasi-equilibrium of isomeric menthone/isomenthone mixture reached via enolization was evaluated under sub- and supercritical conditions and the Gibbs energies of the isomerization in each alcohol were calculated.
KW - Base-free
KW - Enolization
KW - Menthone
KW - Raney® nickel
KW - Supercritical alcohols
KW - Transfer hydrogenation
KW - TRANSFER REDUCTION
KW - HEAVY OIL
KW - Raney (R) nickel
KW - STEREOSELECTIVE HYDROGENATION
KW - N-METHYLATION
KW - KETONES
KW - BIO-OIL
KW - KINETICS
KW - RANEY(R) NI
KW - VERLEY REDUCTION
KW - CATALYSTS
UR - http://www.scopus.com/inward/record.url?scp=85058705730&partnerID=8YFLogxK
U2 - 10.1016/j.supflu.2018.12.011
DO - 10.1016/j.supflu.2018.12.011
M3 - Article
AN - SCOPUS:85058705730
VL - 145
SP - 162
EP - 168
JO - Journal of Supercritical Fluids
JF - Journal of Supercritical Fluids
SN - 0896-8446
ER -
ID: 17879750