J. Agric. Food Chem. 2001, 49, 5761−5764
5761
Lip a se-Ca ta lyzed Syn th esis of F a tty Acid Dieth a n ola m id es
†
‡
,‡
Kuan J u Liu, Ahindra Nag, and J ei-Fu Shaw*
Department of Food Science and Technology, Tungfang J unior College of Technology and Commerce,
Kaohsiung, Taiwan, 82901, and Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan 11529
Diethanolamides are nonionic emulsifiers widely used in industries such as cosmetics and as
corrosion inhibitors. Candida antarctica lipase (Novozym 435) was used to catalyze the amidation
of various fatty acids with diethanolamine. Contents of fatty acids, metal ions, and water affected
the yields of diethanolamides. Hexanoic acid was the best substrate among all acyl donors. Yields
of hexanoyl diethanolamide (HADEA), lauroyl diethanolamide (LADEA), and oleoyl diethanolamide
(
OADEA), obtained after 24 h of lipase-catalyzed reaction at 50 °C and 250 rpm with 90 mM fatty
acid and 360 mM diethanolamine in acetonitrile, were 76.5, 49.5, and 12.1%, respectively. Addition
of 1 mM metal salts increased the yields of HADEA and LADEA. Kinetic analysis showed that the
yields of HADEA and LADEA in lipase-catalyzed reactions were largely associated with the rate of
the forward reaction constant k1. Anhydrous enzyme was found to be the best for the amidation
reaction. Study on the enzyme operational stability showed that C. antarctica lipase retained 95
and 85% of the initial activity for the syntheses of HADEA and LADEA, respectively (even after
repeated use for 10 days). The reaction runs smoothly without the use of hazardous reactants, and
the developed method is useful for the industrial application.
Keyw or d s: Fatty acids; lipase; Candida antarctica; diethanolamides
INTRODUCTION
diethylamine that results to form N,N′-bis(2-hydroxy-
ethyl)piperazine or morpholine (8, 9). Thus, all of these
processes are tedious and require large amounts of
energy.
In view of these drawbacks, an attempt was made to
develop an enzymatic reaction as an alternative low-
cost and low-energy-consuming industrial process. In
the present work, we found that various diethanol-
amides can be efficiently synthesized from diethanol-
amine and various fatty acids using Candida antarctica
lipase (Novozym 435). The effects of acyl donors, organic
solvents, temperature, water content, kinds of lipases,
and operational stability were investigated.
Fatty acid amides have a broad spectrum of use as
detergents, shampoos, cosmetics, lubricants, foam con-
trol agents, fungicides, corrosion inhibitors, and water
repellents (1). Owing to their low reactivity and thermal
properties they are used for the preparation of anti-slip
and anti-block additives in polyethylene films and as
flow improvers (2).
The desired amide can be produced by a Schotten
Bauman reaction using fatty acyl chloride and amine
as reactants. J orden and Port reported conversion of
n-butylamine and methyl stearate to n-butyl stearamide
using sodium methoxide as catalyst (3). Magg (4)
suggested the preparation of desired diethanolamide
and amine ester by reacting 2 mol of fatty acid and 1
mol of diethanolamine at 180 °C. However, such meth-
ods are rather hazardous.
Diethanolamides can be also prepared by amidation
of natural oil. Bilyk et al. (5) synthesized monosubsti-
tuted fatty amides by reacting primary amine with
vegetable oil, tallow, and fish oil. The reaction was
carried out at the boiling point of amine using a molar
ratio of oil and amine of 1:8. Amides are produced
industrially from the fatty acids and alkanolamines by
heating them at 140-160 °C during 6-14 h in an
agitated vessel with a means of removing excess of
amine, water, or alcohol (6). Another industrial method
is based on the reaction of 2 mol of fatty acid with 1
mol of ethylenediamine at 180-185 °C during 6 h under
nitrogen and with continuous removal of water (7).
However, high temperature causes self-condensation of
MATERIALS AND METHODS
Nine lipases were obtained from available commercial
sources. Lipase from Aspergillus niger (Amano AP6), Mucor
sp. (Amano MAP-10), Penicillium camembertii (Amano G),
Pseudomonas cepaceia (Amano PS), and Rhizopus sp. (Amano
N, concentrated) were purchased from Amano International
Enzyme Co. (Nagoya, J apan). Lipases from Candida antarctica
(Novozym 435) and Mucor miehei (Lipozyme IM) were pur-
chased from Novo Nordisk Inc. (Danbury, CT). Porcine pan-
creatic lipase and lipase from Candida cylindracea were
purchased from Sigma Chemical Co. (St. Louis, MO). Dietha-
nolamine, hexanoic acid, hexanoic anhydride, lauric acid,
lauric anhydride, oleic acid, oleic anhydride, methyl laurate,
and tricaprin were purchased from Merck Chemical Co.
(Darmstadt, Germany). All other chemicals were of reagent
grade.
For a standard reaction, the commercial lipase powder
(0.15-0.25 g) was added to a reaction mixture (1 mL) contain-
ing 90 mM fatty acid and 360 mM diethanolamine in aceto-
nitrile. The reaction mixture was incubated in an orbital
shaker at 250 rpm and 50 °C during 24 h. At various time
points 1 µL of the reaction mixture was withdrawn and
analyzed.
*
Corresponding author (fax 886-2-27821605; e-mail
boplshaw@gate.sinica.edu.tw).
†
Tungfang J unior College of Technology and Commerce.
Academia Sinica.
The preliminary identification of the products was done
according to Fink’s method (10). Analytical thin-layer chro-
‡
1
0.1021/jf0107858 CCC: $20.00 © 2001 American Chemical Society
Published on Web 11/07/2001