Esterification of long chain aliphatic acids with long chain alcohols catalyzed by multi-valent metal salts

Article abstract of DOI:10.1246/cl.2005.1502

Some typical multi-valent metal salts, such as chloride, nitrate, sulfate, and acetate of Fe(III), Al(III), Ga(III), In(III), Zr(IV), Hf(IV), Zn(II), Co(II), Ni(II), Mn(III), Cr(III), and Cu(II) have catalytic acitivties for the esterification of saturated and unsaturated long chain aliphatic acids with long chain aliphatic alcohols. These catalysts were sponteneously separated from the reaction mixtures, and could be subjected to the recycle use for the further reactions. Copyright

Full text of DOI:10.1246/cl.2005.1502

1
502
Chemistry Letters Vol.34, No.11 (2005)
Esterification of Long Chain Aliphatic Acids with Long Chain Alcohols
Catalyzed by Multi-valent Metal Salts
Ã
Kshudiram Mantri, Ryo Nakamura, Kenichi Komura, and Yoshihiro Sugi
Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Gifu 501-1193
(Received June 30, 2005; CL-050844)
Some typical multi-valent metal salts, such as chloride,
temperature, and the catalyst was separated from the reaction
mixture by filtration. The aliquots were analyzed by GC to deter-
mine the conversion and product yield.
nitrate, sulfate, and acetate of Fe(III), Al(III), Ga(III), In(III),
Zr(IV), Hf(IV), Zn(II), Co(II), Ni(II), Mn(III), Cr(III), and Cu(II)
have catalytic acitivties for the esterification of saturated and
unsaturated long chain aliphatic acids with long chain aliphatic
alcohols. These catalysts were sponteneously separated from
the reaction mixtures, and could be subjected to the recycle
use for the further reactions.
Table 1 summarizes the esterification of palmitic acid
(hexadecanoic acid) with cetyl alcohol (1-hexadecanol) using
metal chloride catalysts. Unexpectedly, catalytic activities for
the esterification were observed on the wide range of metal salts.
Particularly, Fe(III), Ga(III), In(III), and Zn(II) chlorides showed
very high catalytic activities for the esterification (Table 1,
Entries 1 and 3–5): their activities were in higher or comparable
.
1
6
Esters of long chain aliphatic acid and alcohols are used as
emulsifiers or oiling agents for foods, personal care emollients;
surfactants and base materials for perfumery; spin finishes and
textiles; lubricants for plastics; paint and ink additives and for
2
level of ZrOCl2 8H O (Table 1, Entry 6). Al(III), Co(II),
Ni(II), Mn(III), Cr(III), and Cu(II) chlorides gave the good
to moderate yield of cetyl palmitate (Table 1, Entries 2 and
8–12); however, Mg(II), Ca(II), and Na(I) chlorides had no
catalytic activities for the esterification (Table 1, Entries 13–15).
Table 2 summarizes activities of metal salt catalysts in the
esterification of palmitic acid with cetyl alcohol. Chlorides have
higher activities among the salts, and nitrate, sulfate, and acetate
have the high to moderate catalytic activities. The order of the
activity was also very similar to that of the chlorides. These
results suggest that cationic metal moieties play an important
role on catalytically active species.
1
mechanical processing, etc. They are also used as solvents or
co-solvents, and oil carrier in agricultural industry. However,
they have been produced conventionally by the esterification
of acid and alcohols using mineral acid, such as concentrated
2
,3
sulfuric acid, as catalyst. These catalysts, in general, suffer
from the inherent problem of corrosiveness, high susceptibility
to water, difficulty in catalyst recovery, environmental hazards,
waste control, etc. It is important to replace these highly corro-
sive, hazardous, and polluting acids with environment conscious
catalysts, which are active under mild conditions, and easily re-
covered, and reused for the new reactions.
Table 3 shows the esterification of saturated, branched, and
unsaturated aliphatic acids with primary and secondary alcohols
using ferric and other chlorides. The catalytic activities in the
Recent concerns are homogeneous and heterogeneous cata-
lysts for the esterification of carboxylic acid with an equal
amount of alcohols.4 Very recently, Yamamoto and his co-
workers reported the esterification of carboxylic acids with equi-
.
2
esterification of palmitic acid using FeCl3 6H O were decreased
–16
Table 1. The esterification of palmitic acid with cetyl alcohol
a
catalyzed by metal chloride
1
1–14
molar alcohols using zirconyl and hafnoyl chlorides.
.
Bartoli
and his co-workers also described Zn(ClO4)2 6H2O catalyzed
Entry
Metal salt
.
Yield/%
b
1
2
3
4
5
6
7
8
9
FeCl3 6H2O
95.8
73.8
97.5
98.6
81.5
86.2
98.7
70.5
48.8
53.8
32.3
37.7
12.5
14.0
13.0
12.8
condensation of nearly equimolar amount of acids and alcohols
without solvent.15 We described successful synthesis of the es-
.
AlCl3 6H2O
GaCl3
ters with the combination of ‘‘long chain acids and long chain
alcohols,’’ where carbon numbers are both equal to or higher
InCl3
ZnCl2
.
.
than 10, using unsupported and supported ZrOCl2 8H2O as the
catalysts.1
6,17
ZrOCl2 8H2O
These results encouraged us to investigate catalyt-
.
HfOCl2 8H2O
ic performances of some multi-valent metal salts. In this paper,
we describe surprising catalytic performances of some metal
salts of Fe(III), Al(III), Ga(III), In(III), Zr(IV), Hf(IV), Zn(II),
Co(II), Ni(II), Mn(III), Cr(III), and Cu(II) in the esterification
of saturated and unsaturated long chain acids with long chain
alcohols.
The esterification was carried out in a single-necked, round-
bottomed flask (100 mL) equipped with a Teflon-coated magnet-
ic stirring bar and a Dean-Stark apparatus surmounted with a
reflux condenser. Equimolar amounts of each of the substrates
.
CoCl2 6H2O
.
CrCl3 6H2O
.
10
11
12
MnCl2 4H2O
.
NiCl2 6H2O
.
CuCl2 2H2O
.
13
14
15
16
MgCl2 6H2O
.
CaCl2 2H2O
NaCl
—
(
6 mmol) and metal salts (0.12 mmol) in 40 mL of mesitylene
were charged into the round-bottomed flask. The mixture was
a
Reaction conditions: substrate: palmitic acid, 6 mmol, cetyl
alcohol, 6 mmol; catalyst: 0.12 mmol; solvent, mesitylene
ꢀ
ꢀ
heated to reflux in boiling mesitylene (162 C). After 24 h, the
temperature of the reaction mixture was cooled down to ambient
40 mL; reaction temperature, 162 C; reaction time, 24 h.
b
Similar results were obtained by anhydrous FeCl as catalyst.
3
Copyright Ó 2005 The Chemical Society of Japan

Chemistry Letters Vol.34, No.11 (2005)
1503
Table 2. The esterification of palmitic acid with cetyl alcohol
a
hol and 2-decanol using FeCl3 6H2O occurred to give corre-
sponding esters in high yields (Table 3, Entries 13–16). In these
cases, no isomerization of unsaturated acids to trans-isomers was
observed during the esterification.
.
catalyzed by metal salts
Yield/%
Metal
salt
Chloride
Nitrate
Sulfate
Acetate
The esterification of isostearic acid (2-heptylundecanoic
Fe(III)
Al(III)
Ga(III)
In(III)
Zr(IV)
Zn(II)
Co(II)
95.8
73.8
97.5
98.6
86.2
81.5
70.5
93.5
53.6
98.0
95.6
92.5
76.6
71.8
88.2
49.2
.
acid) with cetyl alcohol and 2-decanol using FeCl3 6H2O was
b
72.4
less active than the case of palmitic acids (Table 3, Entries 17
and 18). Particularly, the reactivity with 2-decanol was low even
in the presence of five fold amount of catalyst.
89.1
84.3
79.5
72.2
88.0
78.2
65.0
We could suggest that these activities appeared by hydro-
1
8
lyzed cationic species of multi-valent metal salts. Particularly,
there is a possibility of the participation of cationic metal clus-
ters of Fe(III), Al(III), Ga(III), In(III), Zr(IV), Hf(IV), Zn(II),
Co(II), and Ni(II), which are formed easily in their aqueous
solutions.
In conclusion, some multi-valent metal salts of iron, alumi-
num, gallium, indium, and zinc were effective catalysts for the
esterification of long chain carboxylic acids with long chain pri-
mary and secondary alcohols. Metal salts, such as chloride, ni-
trate, sulfate, and acetate, are highly active for the esterification,
and gave almost the same yield of esters.
aReaction conditions: substrate: palmitic acid, 6 mmol, cetyl
alcohol, 6 mmol; catalyst: 0.12 mmol; solvent, mesitylene
ꢀ
4
0 mL; reaction temperature, 162 C; reaction time, 24 h.
.
b
Al2O(OAc)4 nH2O.
Table 3. The esterification of some acids and alcohols cata-
a
lyzed by metal chloride
Matal
salt
Yield
/%
Entry
Acid
Alcohol
The investigation on further aspects of the catalysis, partic-
ularly, on catalytic active species and the recyclability of cata-
lysts, is under progress, and will be published in near future.
c
1
2
3
4
5
6
7
8
9
Fe(III) Palmitic acid
Fe(III) Palmitic acid
Fe(III) Palmitic acid
Fe(III) Palmitic acid
Fe(III) Palmitic acid
Al(III) Palmitic acid
Ga(III) Palmitic acid
In(III) Palmitic acid
Zn(II) Palmitic acid
Fe(III) Palmitic acid
Fe(III) Palmitic acid
Fe(III) Palmitic acid
Lauryl alcohol
Myristyl alcohold >99
>99
Cetyl Alcohol
Stearyl alcohole
2-Decanol
95.8
84.5
83.6
67.4
82.5
87.0
36.2
82.5
78.8
69.8
91.6
96.0
97.0
95.2
88.7
40.0b
A part of this work was financially supported by a Grant-in
Aid for Scientific Research (B) 16310056, the Japan Society for
the Promotion of Science (JSPS). KM is also grateful to JSPS for
the postdoctoral fellowship.
2-Decanol
2-Decanol
2-Decanol
2-Decanol
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b
c
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16
17
18
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Published on the web (Advance View) October 8, 2005; DOI 10.1246/cl.2005.1502