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@PHDTHESIS{Dylong:1027007,
author = {Dylong, Dominik},
othercontributors = {Palkovits, Regina and Eisenacher, Matthias},
title = {{W}aste2{M}enthol: development of new synthesis route for
(−)-menthol from pulp and paper industrial waste},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2026-01131},
pages = {1 Online-Ressource : Illustrationen},
year = {2026},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2026},
abstract = {Because of its fresh aroma and cooling effect,
(−)-menthol is widely used in the food, cosmetic and
pharmaceutical industries as a flavouring and fragrance
agent. With its rising popularity, natural menthol extracted
from mint can no longer meet the global demand and is
increasingly replaced by synthetic menthol. As the
established synthesis methods struggle with modern
requirements for sustainability, new approaches to synthetic
“green” menthol will be needed in the future. This work
presents a novel synthesis route for the production of
menthol, designed based on the principles of green
chemistry. The bicyclic monoterpene 3-carene was chosen as
the starting material due to its abundance in crude sulphate
turpentine (CST), which is a by-product of the pulp and
paper industry. The high reactivity of the strained bicyclic
structure of the starting material allows for a
transformation to menthol in four steps: (1) saturation of
the alkene 3-carene to carane by hydrogenation, (2)
transformation of carane to a mixture of isomeric alkenes
(menthenes) via scission of a C-C bond, (3) epoxidation of
menthenes and (4) hydrogenation of epoxymenthanes to the
corresponding alcohols (menthols). For the individual steps,
catalyst screening and optimisation of reaction conditions
were conducted. For the initial step, various commercially
available heterogeneous supported platinum group metal
catalysts and Raney nickel were identified as suitable
catalysts for the saturation of 3-carene, while significant
differences in activity and stereoselectivity were observed.
The following isomerisation of carane was conducted over
solid acid catalysts and homogeneous acids. As the
stereoselectivity of this step is crucial for the overall
yield of the route, the focus was on the possible shape
selective properties of microporous zeolitic catalysts.
However, no significant improvement regarding
stereoselectivity was achieved in comparison to homogeneous
acids and acidic ion exchange resin. For the epoxidation of
menthenes, a suitable biphasic phase transfer catalytic
system with hydrogen peroxide as the oxidant and a
polyoxometalate as catalyst, was successfully optimised to
reduce the formation of by-products by hydrogenolysis.
Finally, the reduction of the epoxides via hydrogenation
over Raney nickel to a mixture of menthols, from which
(−)-menthol can be obtained with suitable methods through
isomerisation, was established. Additionally, the
isomerisation of the epoxide to the corresponding ketone
(menthone) was proposed as an alternative, circumventing the
possible epoxide decomposition under hydrogenation
conditions. This comparatively short synthesis route
combines sustainable raw materials and reagents,
heterogeneous catalysis, solvent free conditions and minimal
waste generation into an attractive new approach to menthol
production. The feasibility of the route was successfully
demonstrated, including kinetic and mechanistic
investigations, catalyst screening and optimisation of
reaction conditions for the individual steps. The remaining
challenges for this synthesis are the medium
stereoselectivity of the carane isomerisation step and the
separation of undesired isomeric by-products.},
cin = {155310 / 150000},
ddc = {540},
cid = {$I:(DE-82)155310_20140620$ / $I:(DE-82)150000_20140620$},
pnm = {BMFTR 13FH035PX8 - FHprofUnt 2018: Synthese von
L-(-)-Menthol aus Abfällen der Papierindustrie
(Waste2Menthol) (13FH035PX8)},
pid = {G:(BMFTR)13FH035PX8},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2026-01131},
url = {https://publications.rwth-aachen.de/record/1027007},
}
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