EP1053974A1
Expired / Lapsed
EP
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Reactions using lewis acids
Assignee: Givaudan Nederland Services BV
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Filing: 1999-05-17
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Granted: —
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Expires: 2019-05-17
Abstract
Abstract In a method of performing a chemical reaction using a Lewis acid, after reaction the Lewis acid is extracted from the reaction product in the form of an aqueous solution, followed by drying of the aqueous solution of the Lewis acid. The dried Lewis acid can be reused in a further similar reaction. The method can be repeated several times, using the same batch of Lewis acid, without the activity and specificity of the Lewis acid being significantly affected. The invention has been used to good effect in the preparation of isopulegol from citronellal using zinc bromide as a Lewis acid catalyst for the cyclisation reaction. The invention can thus provide an environmentally acceptable and efficient process for the production of isopulegol from citronellal, in both racemic and enantiomerically pure forms.
Inventors
- 👤 designation of the inventor has not yet been filed The
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 22:47
CPC Classifications
C; C07; C07C; C07C29/00; C07C29/17; C07C29/172; C01; C01G; C01G9/00; C01G9/003; C01G9/04; C07B; C07B63/00; C07C29/56; C07C2601/00; C07C2601/12; C07C2601/14
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
44 words
A method of performing a chemical reaction involving a Lewis acid, comprising
carrying out the reaction involving the Lewis acid; extracting from the reaction
products the Lewis acid in the form of an aqueous solution; and drying the aqueous
solution of the Lewis acid.
Claim 2
Dependent Claim
33 words
A method according to claim 1, wherein the Lewis acid is extracted from the
reaction products by adding water, and separating the aqueous fraction from an
organic solvent fraction containing other reaction products.
Claim 3
Dependent Claim
23 words
A method according to claim 1 or 2, wherein drying of the aqueous solution of the
Lewis acid is performed by azeotropic distillation.
Claim 4
Dependent Claim
20 words
A method according to claim 1, 2 or 3, wherein the dried Lewis acid is used in a
further reaction.
Claim 5
Independent Claim
20 words
A method according to any one of the preceding claims, preceded by an initial step
of drying the Lewis acid.
Claim 6
Independent Claim
59 words
A method of performing a chemical reaction involving a Lewis acid, comprising
the steps of: 1) drying an aqueous solution of Lewis acid; 2) using the dried Lewis acid in the chemical reaction; 3) adding water to the reaction products of step 2) and separating an aqueous solution
of the Lewis acid; and 4) repeating steps 1) to 3).
Claim 7
Independent Claim
50 words
A method of preparing isopulegol from citronellal, comprising reacting citronellal
in the presence of a Lewis acid catalyst to cause cyclisation of citronellal to produce
isopulegol; extracting from the reaction products the Lewis acid in the form of an
aqueous solution; and drying the aqueous solution of the Lewis acid.
Claim 8
Dependent Claim
13 words
A method according to claim 7, wherein the Lewis acid is zinc bromide.
Claim 9
Dependent Claim
17 words
A method according to claim 7 or 8, wherein the cyclisation reaction is carried out
in toluene.
Claim 10
Dependent Claim
28 words
A method according to claim 7, 8 or 9, wherein the cyclisation reaction is carried
out at a temperature in the range -15°C to 30°C, preferably about 0°C.
Claim 11
Independent Claim
36 words
A method according to any one of claims 7 to 10, wherein the Lewis acid is
extracted from the reaction products by adding water, and separating the aqueous
fraction from an organic solvent fraction containing isopulegol.
Claim 12
Independent Claim
26 words
A method according to any one of claims 7 to 11, wherein drying of the aqueous
solution of the Lewis acid is performed by azeotropic distillation.
Claim 13
Dependent Claim
14 words
A method according to claim 12, wherein the azeotropic distillation is performed
using toluene.
Claim 14
Dependent Claim
17 words
A method according to claim 12 or 13, wherein the azeotropic distillation is
preceded by vacuum dehydration.
Claim 15
Independent Claim
30 words
A method according to any one of claims 7 to 14, wherein the dried Lewis acid is
used as catalyst in a further cyclisation reaction of citronellal to produce isopulegol.
Claim 16
Independent Claim
21 words
A method according to any one of claims 7 to 15, preceded by an initial step of
drying the Lewis acid.
Claim 17
Independent Claim
65 words
A method of preparing isopulegol from citronellal, comprising the steps of: 1) drying an aqueous solution of zinc bromide by azeotropic distillation using
toluene; 2) using the dried zinc bromide as a catalyst for cyclisation of citronellal to produce
isopulegol; 3) adding water to the reaction products of step 2) and separating an aqueous solution
of zinc bromide; and 4) repeating steps 1) to 3).
Claim 18
Independent Claim
22 words
A method according to any one of claims 7 to 17, wherein 1-isopulegol is
prepared from d-citronellal, without change in optical purity.
Claim 19
Independent Claim
19 words
A method according to any one of claims 7 to 18, further comprising converting
the resulting isopulegol to menthol.
Claim 20
Dependent Claim
12 words
Isopulegol prepared by the method of any of claims 7 to 19.
Claim 21
Dependent Claim
8 words
Menthol prepared by the method of claim 20.
References Cited (Backward Citations)
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