Organic synthesis of cis-9 and trans-9 octadecenes from oleyl alcohol and elaidyl alcohol, respectively, by conversion to tosylates followed by lithium aluminum hydride reductio

Dyen, M. E.

Hamann, H. C.

Swern, D.

English

NASA Technical Reports Server

Improved Preparation of 9-Octadecenes 
1 Martin E. Dyen, Herman C. Hamann, and Daniel %ern 
Fels Research Institute and Department of Chemistry 
Temple University, Philadelphia, Pennsylvania 19122 
J. Am. Oil Chemists' SOC. - 43, 431-432 (1966) 
Abstract 
- cis-and trans-9-Octadecenes have been obtained in about 55-60% yield on a 
preparative scale by an improved procedure from commerically pure oleyl al- 
cohol (90-95%) and elaidyl alcohol, respectively, by conversion to the 
tosylates followed by reduction with lithium aluminum hydride (LAH). The 
improvement consists in using saturated sodium chloride solution to coagu- 
late the slimy, intractable, insoluble salts obtained after the LAH re- 
duction and destruction of excess LAH with water, prior to ether extraction 
of the crude hydrocarbons. 
three days. 
Total time required for the preparation is about 
- cis- and trans-9-Octadecene are valuable model compounds for usein the 
development and study of new reactions of fats and their derivatives. The 
introduction of functional groups into these relatively simple, uncomplicated 
molecules can be readily followed by a variety of physical and chemical 
methods. Since the solubility and volatility characteristics of these long 
chain unsaturated hydrocarbons are similar to those of fatty acid derivatives, 
it is preferable to use them as model compounds rather than analogous shorter 
chain olefins, such as trans-3-hexene and 2-octene. 
The preparation of cis- and trans-9-octadecene from methyl o€eate and 
elaidate (or oleyl and elaidyl alcohol), respectively, is described in the 
literature (l), but the procedures are inadequately described or the scale of 
the preparation is too small to be generally useful. Most important, however, 
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is that the literature procedures, at least in our hands, are not readily 
duplicated and leave much to be desired in the way of yield and purity of 
final products. 
The usual procedure for obtaining the 9-octadecenes is:(a) reduction 
of methyl oleate or elaidate with lithium aluminum hydride (LAH) to the 
corresponding alcohols, (b) conversion of the alcohols to the toluenesulfonate 
esters (tosylates), (c) reduction of the tosylatss v i t h  LAH to the unsaturated 
hydrocarbons, and (d) fractional distillation of the crude hydrocarbons. 
Flowsheet 1 summarizes the procedure. 
Although the yields in each step are high, the major problem in the 
reaction sequence shown in Flowsheet 1 is the separation of the crude un- 
saturated hydrocarbons from the tosylate reduction mixture. 
after destruction of excess LAH with water, also contains slimy, intractable 
inorganic salts and salts of toluenethiol, the other reduction product of 
the tosylate. Acidification of this reduction mixture dissolves the insoluble 
salts and permits facile extraction of the hydrocarbons but toluenethiol is 
also formed and this compound is a good cis-trans isomerization catalyst, be- 
sides having an objectionable odor. The presence of toluenethiol in the hy- 
drocarbons during the final workup and especially during the fractional di- 
stillation should be scrupulously avoided. Alternatively, the slimy salts 
can be separated by filtration but the experience is very discouraging,es- 
pecially on a preparative scale (100-2OOg.) 
This mixture, 
We have found that the final reaction mixture can be maintained on the 
alkaline side and the hydrocarbons readily extracted from the lithium and/or 
aluminum salts by adding saturated sodium chloride solution. This coagulates 
the inorganics and permits the extraction with ether to proceed readily. The 
ether solution is dried and, after evaporation of the ether, the crude hydro- 
carbons are distilled. 
In the work described in this Note, we started with a good commercial 
grade of oleyl alcohol containing about 90-95% octadecenols, of which about 
one-fourth had the trans- configuration (Fig. 1). This starting material was 
selected because of its low price and availability and also because we wished 
to test and check the procedure on a fairly large scale with both undergra- 
Methyl oleate (or elaidate) 
LAH (ether or tetrahydrofuran) 1 
Oleyl alcohol (or elaidyl alcohol) 
Toluenesulfonyl chloride-pyridine 
Oleyl tosylate (or elaidyl tosylate) 
LAH (tetrahydrofuran) 
- cis-9-Octadecene (trans-9-Octadecene) 
FLOWSHEET 1 
and graduate students. 
an expenditure of time and money to obtain 100% cis-9-octadecenol. 
We did not wish to commit ourselves to too large 
The most important question to be answered was whether the cis/trans 
ratio i s  altered by the procedure. The octadecenes we obtained from 
commercial oleyl alcohol contained about 15-20% of trans-isomers (Fig.2), 
showing apparently that no alteration in the double bond system had 
~ r c u r r e d ,  Overall yield of distilled 9-octadecenesY b.p. 133O/0.5 nun., 
was 55% based on the oleyl alcohol starting material. 
10'x1/4" 10% butanediol succinate column on Anakron ABS showed that the 
hydrocarbon product contained >98% of C-18. Portions of three consecutive 
working days were sufficient for the preparation. 
GLC analysis on a 
The procedure was repeated on a larger scale with the more readily 
accessible pure trans-9-octadecenol (elaidyl alcohol) (Fig. 3) as the 
starting material. trans-9-Octadecene, b.p. 138-141°/0.3 mm. and m.p. 
12-13', was obtained (Fig. 4) in about 60% yield from the alcohol. The 
melting point of the trans-9-octadecene we obtained was significantly 
higher than the literature value of 5O (1). 
Experimental 
Starting Materials: Ado1 90, obtained from the Archer-Daniels-Midland C o . ,  
was used for the preparation of 9-octadecenes. It contained about 20% of 
trans-isomers (Fig. 1). Elaidyl alcohol (Fig. 3),m.p. -35.3-36.0°, was 
prepared from pure oleyl alcohol by short-time selenium isomerization at 
225' (2). LAH was obtained from Metal Hydrides, Inc. All solvents were 
of highest quality; they were dried and distilled before use. prToluene- 
sulfonyl chloride, m.p. 63-5O, was Eastman White Label Grade. 
Infrared Spectra: A Perkin-Elmer Infracord Spectrophotometer Model 137 3 with 
0.103 mm. matched cells was used. 
tetrachloride were examined. Infrared spectra are sham in Figs. 1-4. 
Procedure: 9-0ctadecenes. In a 1 liter, three-neck flask equipped with a 
stirrer and thermometer, commercial oleyl alcohol (100 g.; 0.37 mole) was 
dissolved in 200 ml. of dry pyridine. The stirred solution was cooled to 
10-15' in an ice bath and p-toluenesulfonyl chloride (96 g.; 0.5 mole) was 
Approximately 4% solutions in carbon 
-4 - 
added i n  3-5 equal por t ions  over a 30-45 minute period. 
s t i r r e d  f o r  2-3 hours and then placed i n  a r e f r i g e r a t o r  overnight.  
The s o l i d - l i q u i d  s l u s h  from the  r e f r i g e r a t o r  was poured i n t o  a se- 
The s o l u t i o n  w a s  
paratory funnel and ex t rac ted  with 4 x 200 m l .  of petroleum e the r  using a 
minimum volume of water (10-20 m l . )  o r ,  i f  necessary,  s a tu ra t ed  sodium 
ch lo r ide  so lu t ions  t o  separa te  the  layers .  The combined petroleum e t h e r  
extracts w e r e  washed with 10 x 250 m l .  of w a t e r ,  d r i e d  over anhydrous 
magnesium s u l f a t e  and f i l t e r e d .  Evaporation of t h e  so lvent  under vacuum 
i n  a r o t a r y  evaporator yielded 137 g. (87% y ie ld )  of t o s y l a t e s  as a p a l e  
yellow o i l .  
The t o s y l a t e s ,  dissolved i n  300-500 m l .  of anhydrous te t rahydro-  
fu ran  (THF), were added dropwise over a 30-45 minute period to  a s t i r r e d  
r e f lux ing  mixture of 500 m l .  of THF and LAH (15 g.; 0.4 mole) i n  a three-neck 
f l a s k  equipped with a n  e f f i c i e n t  condenser to  which a calcium ch lo r ide  drying 
tube was a t tached .  
continued f o r  an add i t iona l  30-45 minutes. 
When add i t ion  vas complete, s t i r r i n g  and r e f lux ing  w e r e  
The hea te r  w a s  then replaced by an  ice ba th  and t h e  r eac t ion  mixture 
w a s  cooled to  room temperature. With caut ion ,  10 m l .  of a 10% aqueous so- 
l u t i o n  of sodium hydroxide w a s  added dropwise t o  des t roy  the  excess LAH. 
I n  t h i s  s t e p ,  considerable  heat  i s  evolved and an e f f i c i e n t  ice ba th  should 
b e  used. To coagulate  the  insoluble  salts, 100-200 m l .  of a sa tu ra t ed  so- 
dium ch lo r ide  so lu t ion  w a s  added and t h e  mixture w a s  s t a r ed  overnight  i n  a 
r e f r i g e r a t o r .  
The so l id - l iqu id  mixture w a s  ex t rac ted  i n  por t ions  with 3 x 100 m l .  
volumes of e the r  and t h e  lower aqueous phase containing salts  was  discarded.  
(Occasionally sa tu ra t ed  sodium chlor ide  so lu t ion  had to  be added to  e f f e c t  
a c l ean  separa t ion  of layers ) .  
u n t i l  f r e e  of sal t ,  dr ied  over anhydrous magnesium s u l f a t e  and f i l t e r e d .  
Evaporation of t he  e t h e r  i n  a ro t a ry  evaporator gave 68 g. (04% y ie ld  based 
on to sy la t e )  o f  crude hydrocarbons as a yellow o i l .  D i s t i l l a t i o n  through a 
3' x 1" heated Vigreux column yielded 55 g. (59% y ie ld  based on o l e y l  a l -  
26  cohol)  of c o l o r l e s s  9-octadecenesY b.p. 133O/0.5 mm. The hea r t  c u t  had n, 
. 
The e t h e r  extracts w e r e  washed wi th  water 
u 
1.4464 fiit. 4' 1.4450 (1) 1 and contained about 17% of t r ans  isomers 
-5- . 
. . 
(Fig. 2) ( 3 ) .  GLC analysis through a 10' x 1/4" 10% butanediol succinate 
column of Anakron ABS indicated >98% C-18. 
trans-9-Octadecene. In similar fashion, elaidyl alcohol (200 g.; 0.75 mole) 
and p-toluenesulfonyl chloride (160 g.; 0.83 mole) in 500 ml. of dry pyridine 
yielded 235 g. (75%) of elaidyl tosylate which on LAH reduction in a total of 
1700 ml of refluxing THF for two hours followed by fractional distillation 
yielded I05 g.  (55% yield based on elaidyl alcohol) of trans-9-octadecene, 
b.p. 138-141"/0.3 mm. and m.p. 12-13" Liit. 5"  (l)]. 
liquid the infrared spectrum of which ishown in Fig. 4. 
It was a colorless 
Acknowledgment: The authors are grateful to Kenneth Craig and Armin Wolle, 
undergraduates in the Advanced Organic Preparations course at Temple Uni- 
versity, for checking the procedures. This investigation was supported in 
part by Public Health Service Research Grants No. CA-07803 and CA-07174. 
Martin E. Dyen was supported partially under a Training Grant Award 520-831-00 
from NASA. 
Legend For Figures 
Fig .  1: Infrared Absorption Spectrum Of Comercia1 Oleyl Alcohol Starting 
Material. 
-. r l g .  2: Infrared Ahsorption Spectrum O f  9-Octadecenes Obtained From 
Commercial O l e y l  Alcohol. 
F ig .  3: Infrared Absorption Spectrum O f  trans-9-Octadecenol (Elaidyl  Alco- 
h o l ) .  
Fig.  4: Infrared Absorption Spectrum O f  trans-9-Octadecene. 
. 
a 
References 
1. Elsner, B .  B.  and P .  F .  M. Paul, J. Chem. SOC. 1953, 3156. Nordby, H. E . ,  -
B.  W. Heywang, H. W. Kircher, and A. R. Kemmerer, J.A.O.C.S. 39, 183 (1962). -
2 .  Swern, D . ,  E. F .  Jordan, Jr.  and H. B .  Knight, J. Am. Chem. SOC. 68, 1673 -
(1946). 
3 .  Shreve, 9. p,, M. R. Heether, H. B .  Knight and D .  Swern, Anal. Chem. 22, 
1261 (1950), 
concentration: 0.0458 g./ml. 
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Improved preparation of 9-octadecenes

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