Transesterification catalysts fixed to solid support materials

Details Transesterification catalysts fixed to solid support materials Transesterification catalysts fixed to solid support materials

1999-08-09

2001-06-19

Rotman, Alan L. (Department: 1625)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C560S061000

Reexamination Certificate

active

06248899

ABSTRACT:

This application is a 371 of PCT/EP97/06978 filed Dec. 12, 1997.
The present invention relates to immobilized tin-sulfur catalysts, their preparation and their use in transesterification reactions of carboxylic esters.
Transesterification reactions of carboxylic esters can be generally described by the following reaction scheme:
in which R is usually a C
1
-C
4
alkyl radical and R′ and Z are each an organic radical. The reaction is an equilibrium reaction. In general, the (lower-boiling) alcohol liberated is distilled off during the reaction. A series of different catalysts for this reaction are known (Junzo Otera, Chem. Rev., 93 (1993) 1449-1470), e.g. acids, bases, amines, metal alkoxides and also, inter alia, organotin compounds. Many of these esterification reactions are carried out at temperatures in the range from 80° C. to above 200° C.
It is economically advantageous if the reactions can be carried out in the melt without solvents. A further advantage is gained if the product does not have to be purified by distillation or extraction after the reaction. For this reason, a catalyst should be able to be used at high temperatures (reaction in the melt) and the catalyzed reaction must not lead to discolored products.
Organotin compounds are known and very mild catalysts for transesterifications of carboxylic esters with alcohols. A problem associated with conventional tin catalysts is achieving an economical separation of the tin from the reaction product. A possible solution is the use of immobilized tin catalysts which can be separated off.
U.S. Pat. No. 5,436,357 discloses, for example, catalysts bound to polystyrene of the type:
These compounds are proposed as catalysts for transesterifications in a temperature range of 50-150° C. They can be decanted or filtered off and reused a number of times. In most cases, reuse is associated with a drop in activity. No information is given about Sn leaching, for example as residual tin content of the product.
Furthermore, H. Schuhmann and B. Pachaly, J. Organomet. Chem., 233 (1982) 281-289 and H. Schuhmann and B. Pachaly, Angew. Chem., 93 (1981) 1092-93 have described the preparation of the following compounds which are used stoichiometrically as hydrides for the reduction of alkyl halides.
These compounds are immobilized on silica gel (or aluminum oxide) and are converted by reduction into the corresponding hydride reagent:
Essentially the same compounds as in the abovementioned publications are described in DE31 19643.
The present invention provides a process for the transesterification of carboxylic esters, characterized in that the catalyst used is a tin(IV) compound comprising a radical of the formula
bound to an inorganic support, where L is an at least divalent radical and at least one of the free valences of the Si in formula (I) is bound to the inorganic support.
These immobilized tin-sulfur catalysts can be used in a wide temperature range and, after the reaction, can be separated from the reaction product simply and completely by solid/liquid separation operations, for example filtration, centrifugation and decantation. The catalysts which have been filtered off continue to be catalytically active and can be reused a number of times.
The process of the invention is particularly suitable for preparing compounds of the general formula
in which
R
101
and R
102
are identical or different and are H, alkyl having from 1 to 18 C atoms, phenyl,
C
1
-C
4
alkyl-substituted phenyl, phenylalkyl having from 7 to 9 C atoms, C
5
-C
12
cycloalkyl,
C
1
-C
4
alkyl-substituted C
5
-C
12
cycloalkyl or a radical
R
103
is H or CH
3
;
R
105
is H, Cl, SO
3
H or C
1
-C
4
alkyl;
m is 0, 1, 2 or 3; and
n is 1, 2, 3 or 4; where, when n=1,
A is —OR
104
; and
R
104
is alkyl having from 2 to 45 C atoms, C
2
-C
45
alkyl interrupted by one or more oxygen, cycloalkyl having from 5 to 12 C atoms, alkenyl having from 2 to 18 C atoms, —CH
2
CHOHCH
2
OC(O)R
109
or —CH
2
CH
2
—OR
106
; and
R
109
is H, alkyl having from 1 to 8 C atoms, alkenyl having from 3 to 5 C atoms or benzyl;
where
R
106
is
H, alkyl having from 1 to 24 C atoms, phenyl, cycloalkyl having from 5 to 12 C atoms or
and
R
110
is H or —CH
3
;
R
111
is H or alkyl having from 1 to 24 C atoms; and
R
112
is H or —CH
3
, with the proviso that R
110
and R
112
are not simultaneously —CH
3
;
or, when n=2,
A is —O—C
x
H
2x
—O—, —O—(CH
2
CH
2
O)
a
CH
2
CH
2
O— or —O—CH
2
CH═CHCH
2
—O—; in which
a is from 1 to 30; and
x is from 2 to 20;
or, when n=3,
A is
in which
R
107
is alkyl having from 1 to 24 C atoms or phenyl,
or, when n=4,
A is
The process is particularly preferred for preparing compounds of the formula (X) in which n is one;
R
101
is tert-butyl or
R
102
is tert-butyl;
R
103
and R
105
are H;
m is 2; A is OR
104
;
R
104
is (CH
2
)
17
CH
3
, C
8
H
17
(isomer mixture), C
2
-C
45
alkyl interrupted by one or more oxygen,
—CH
2
CHOHCH
2
OC(O)R
109
; and
R
109
is alkenyl having from 3 to 5 C atoms;
or n is 2;
R
101
is tert-butyl or
R
102
is CH
3
;
R
103
is H;
m is 2;
A is —O—(CH
2
CH
2
O)
a
CH
2
CH
2
O—; and
a is from 1 to 30;
or n is 3;
R
101
and R
102
are tert-butyl;
R
103
is H;
m is 2; and
A is —O—CH
2
—CH(O—)—CH
2
—O—;
or n is 4;
R
101
and R
102
are tert-butyl;
R
103
is H;
m is 2; and
A is C(CH
2
—O—)
4
.
The process of the invention is likewise suitable for preparing compounds of the general formula
in which
R
200
and R
201
are, independently of one another, C
1
-C
4
alkyl;
R
202
is H, C
1
-C
18
alkyl, O or C
1
-C
18
alkoxy;
A
200
is, when p=1, C
1
-C
12
alkyl, C
1
-C
12
alkyl substituted by —C(O)OH or C
2
-C
5
alkenyl;
or, when p=2, C
1
-C
12
alkylene; and
p is 1 or 2.
The process of the invention is likewise suitable for preparing compounds which are obtainable by reaction of a compound of the formula
in which
R
210
and R
211
are, independently of one another, C
1
-C
4
alkyl; and
x is from 1 to 12;
with a compound of the formula
R
212
OC(O)—A
210
—(O)COR
213
  (XXXI)
in which
R
212
and R
213
are, independently of one another, C
1
-C
4
alkyl; and
A
210
is C
1
-C
12
alkylene.
The compounds obtainable by reaction of the compounds (XXX) with (XXXI) are, in general, oligomeric or polymeric compounds or mixtures of such compounds. The stoichiometric ratios and reaction parameters make it possible to influence the formation of the compounds or mixtures of compounds.
Examples of the substituents in the formulae (X), (XX), (XXX) and (XXXI) are given below.
Alkyl having up to 45 C atoms can be a linear or branched alkyl group and can be, for example: methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, isopentyl, hexyl, heptyl, 3-heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, 2-ethylbutyl, 1-methylpentyl, 1,3-dimethylbutyl, 1,1,3,3-tetramethylbutyl, 1-methylhexyl, isoheptyl, 1-methylheptyl, 1,1,3-trimethylhexyl, 1-methylundecyl, eicosyl, henicosyl, docosyl, triacontyl and others. Preference is given to alkyl having 1-12 C atoms and particular preference is given to alkyl having 1-8 C atoms. When mention is made of i-C
8
H
17
, this is to be understood as including a mixture of isomers.
A very particularly preferred example of R
101
and R
102
is the t-butyl group. Preference is also given to R
101
=—CH
3
and R
102
=t-butyl or R
101
=isopropyl and R
102
=t-butyl. As R
103
, preference is given to —H. Preferred R
111
, R
107
and R
106
are alkyl groups having from 1 to 18 C atoms.
Examples of cycloalkyl substituents having from 5 to 12 C atoms are cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl and cyclododecyl. Preference is given to cyclohexyl.
Examples of C
1
-C
4
alkyl-substituted cycloalkyl having from 5 to 12 C atoms are 2- or 4-methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl and t-butylcyclohexyl.
Examples of C
1
-C
4
alkyl-substituted phenyl substituents are methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl,

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