Note: Descriptions are shown in the official language in which they were submitted.
788~5
23 SUMMARY OF THE INVENTION
24 This invention relates to a process for the prep-
aration of specifically labelled, saturated fatty acids
26 and to the process for the preparation of specifically . -.
27 labelled unsaturated acids. More specifically, it relates ~
~- 15996
~'7l51~5
1 to multi-step syntheses of fatty acids in which the syn-
2 thesis is designed to minimize the possibility of isotope
3 scrambling. The invention further relates to the novel
4 specifically labelled fatty acids prepared in accordance
with the novel processes. Still more specifically, it
6 relates to a group of novel specifically deuterated pal-
i mitic acids. It also relates to a novel method for pro-
~ ducing such compounds by a synthesis which includes the
g steps of (1) alkylating a compound having a terminal
acetylenic moiety and a terminal functional substituent
11 convertible to carboxyl, and (2) catalytically deuterog-
12 enating the triple bond of the formed acetylenic compound,
13 thus producing an intermediate having only one carbon-
14 carbon linkage completely deuterated and having substan-
tially no deuterium substitution elsewhere in the molecule.
16 BACKGROUND OF THE INVENTION
17 The processes for producing labelled fatty acids
18 employed in the prior art involve the conversion o~ or
19 dinary fatty acids to their deuterated counterparts by
hydrogen-deuterium exchange under conditions leading to
21 partial and/or complete replacement of hydrogen with deu-
22 terium in a statistical basis., This type of deuterium-
23 hydrogen exchange is dif~icult to control, and impossible
24 to limit to the preparation of specifically labelled fatty
acids. Other methods involve the preparation of mixtures
26 of partially deuterated fatty acids and the attempted
27 separation of such mixtures into their component individual
28 compounds by complicated isolation procedures involving
29 gas-liquid chromatography and the like. Still other
.
.
--2--
.
15996
l procedures include the synthesis of unsaturated fatty
2 acids and the catalytic deuteration of such unsaturated
3 acids to produce the corresponding dideuterosubstituted
4 saturated fatty aeids having deuterium present in at
least one specific location in the molecule. ~ drawback
6 to this procedure is the tendency to cause isotope scram
7 bling during the eatalytie deuteration of sueh eompounds.
8 Thus, in the course o the catalytic deuteration of such
9 compounds, one obtains, in addition to the product resul-
ting from saturation of the double bond, a proportion of
ll product in which other hydrogens of the substrate compound
12 have randomly been exehanged with deuterium. This results
13 in the preparation of a mixture of deuterated analogs,
14 whieh either eontaminate the speeifieally labelled produet
or whieh must be separated by diffieult purifieation pro-
16 cesses such as are mentioned hereinabove.
,
17 DESCRIPTION OF THE INVENTION
18 In accordance with the present invention, there
19 is provided a process for the preparation of speeifically
labelled fatty acids using a synthetie sequenee whieh
21 combines the steps of alkylation of a terminal aeetylenie
22 substituent and hydrogenating or deuterogenating the aeet-
23 ylenic bond in the presence of a selective and soluble
24 hydrogenation catalyst. The selection of the substrate
eompounds for the alkylation reaction is based on the
26 desired position of deuterium in the final specifically
27 labelled aeid. This alkylation reaetion establishes the
28 position of the deuterium labelling relative to the carb-
29 oxylic acid funetion in the final eompound.
` 15996
8~a;S
1 The process of the present invention is espe-
2 cially use~ul for the preparation of specifically labelled
; 3 palmitic acids, which contain deuterium substituents spe-
4 cifically affixed to certain positions of the carbon
skeleton. ~hus, by judicious selection of the reacting
6 species, there are prepared in accordance with the present
~ invention, palmitic-5,5,6,6-d4 acid, palmitic-7,7,8,8-d4
8 acid, palmitic -16,16,16-d3 acid, and palmitic-11,11,12,
9 12-d4 acid. The process of the present invention may also
be utilized in the preparation of other specifically deu-
11 terated d4 fatty acids, especially d4 palmitic acids.
12 In accordance with the present lnvention, the
13 starting materials employed include one compound containin~
; 14 a terminal acetylenic moiety and a second compound con-
taining a terminal halogen substituent. The halo compound
16 is the alkylating species, and the number of carbons in
17 the halohydrocarbon determines the length of the alkyl
1~ substituent attached to the terminal acetylene group and
19 therefore the ultimate specific position of deuterium
atoms in the final acid. The starting material which con-
21 tains the terminal acetylene mo1ety also contains~a carb-
22 oxylic acid function or another functional substituent
23 readily convertible to carboxyl but unreactive under the
24 conditions of the alkylation reaction. One such substi-
tuent is an hydroxyl substituent protected from reaction
26 by derivatization as a tetrahydropyranyl ether. Following
27 the alkylation, the tetrahydropyranyl ether is readily
; 28 sleaved to produce the corresponding hydroxy compound which
29 is carefully oxidized to the corresponding carboxylic acid
compound in two stages using pyridium chlorochromate.
~ 15996
,
1 In another procedure, the hydroxyl substituent
2 is first converted to a bromo substituent by treatment
; 3 with a brominating agent such as carbon tetrabromide in
4 the presence of triphenylphosphine, which in turn is meta-
thesized with an alkali metal cyanide, e.g., potassium,
6 to the corresponding nitrile. The nitrile compound is
7 then converted to the corresponding carboxylic acid by
8 hydrolysis with aqueous alkali, as for example, an alkali
9 metal hydroxide (sodium or potassium hydroxide 20~ solu-
tion in water w/v).
11 In one specific embodiment of the invention,
12 the tetrahydropyranyl ether of 5-hexyn-1-ol is alkylated
13 by treatment with l-bromodecane in the presence of a strong
14 base such as butylithium to produce the intermediate 5-
hexadecyl-l-ol. This acetylenic alcohol is then reduced
16 using deuterium gas in the pres`ence of tris-(triphenyl-
17 phosphoro)rhodium chloride as a catalyst to produce the
18 corresponding saturated hexadecane-5,5,6,6-d4-1-ol OD.
19 The resulting saturated alcohol is then oxidized in two
ZO stages using pyridinium chlorochromate to produce the
21 desired specifically labelled palmitic-5,5,6,6-d4~acid.
22 In a second specific embodiment of the inven-
23 tion, the desired acid is produced directly in a two-step
24 sequence which comprises first contacting l-decyne with
6-bromo-hexanoic acid in the presence of butyl lithium to
26 produce directly the acetylenic acid, 7-hexadecynoic acid,
27 which is then converted directly to palmitic 7,7,8,8-d4
28 carboxylic acid by treatment with deuterium gas and tris-
29 ~triphenylphosphoro)rhodium chloride as a catalyst.
~ .
--5--
" :
-. , . ` .
-: ,-, , ' , ` ` ` . '
~ 7~5 15996
1 In a further specific embodiment of the present
2 invention, palmitic-16,16,16-d3 acid is prepared by first
3 contacting 10-undecyn-1-ol ~etrahydropyranyl e~her wi~h
4 1-bromopentane-5,5,5-d3 in the presence of butyl lithium
to produce as a first intermediate, 10-hexadecyn-16,16,16-
6 d3-ol and subsequently hydrogenating said aecynol in the
7 presence o~ tris-(triphenylphosphoro)rhodium chloride to
8 produce the desired product.
9 In a still further specific embodiment of the
present invention, 10-undecyl-1-ol tetrahydropyranyl ether
11 is alkylated using l-bromobutane in the presence of butyl
12 lithium to produce 10-pentadecyn-ol, which is converted
13 to the tetradeutero compound pentadecan-l-ol 10,10,11,11-d4
14 by treatment with deuterium gas in the presence of tris-
(triphenylphosphoro)rhodium chloride as a catalyst. The
16 said pentadecanol is then successively converted to the
17 corresponding halo compound, l-bromopentadecane-10,10,11,
18 11-d4 by treatment with triphenylphosphine and carbon
19 tetrabromiae, followed by metatheses of the bromopenta-
decane with potassium cyanide to produce hexadecanitrile
21 11,11,12,12-d4 which in turn is hydrolyzed usin~ 20% aqueous
22 alcoholic sodium hydroxide solution to produce the desired
23 palmitic-11,11,12,12-d4 acid.
24 The novel, specifically labelled fatty acids of
the present invention are valuable compounds used in many
26 kinds of specialized research work in addition to their
27 utility for the same purposes as the commercially available
28 palmitic acid. General applications include their use in
29 the study of reaction mechanisms, as tracers in the study
of separation processes, and as model compounds for inves-
31 tigation of the physical properties of labelled compounds.
--6--
.. .. . . . - . .. .. . .
~ 7~8~ l5996
1 They are also useful in the study of the naturally occur-
2 ring unlabelled acids in biological systems, and as such
3 may be employed in the clinical diagnosis o~ conditions
4 which involve the production or abstraction of fatty acids.
They are also useful in the study of the metabolism and
6 biosynthe=i= of the corresponding unlabelled compound=.
:.
, .
15996
~t7~b;S
; 1 EXAMPLE 1
~ Palmitic 5,5,6,6-d~ Acid
3 Step A: 4-Chlorobutanol tetrahydropyranyl ether
4 C1~ ~
'
A mixture of 4-chlorobutanol (21.7 9.) and p-
6 toluenesulfonic acid (250 my.)in anhydrous ether is added
7 to dihydropyran (26 ml.) and the reaction mixture is stirred
8 at room temperature overnight. There is an initial mild
g exothermic reaction. The solution is then diluted with
ether (200 ml.) and washed twice with 0.1 M sodium carbonate
11 solution/ the ether layer containing the product is dried
12 with potassium carbonate and evaporated under reduced pres-
13 sure, leaving a residue containing 4-chlorobutanol tetra-
14 hydropyranyl ether. The residue is distilled, and the
fraction at 74-76C./0.3 mm. ~g. is collected. Analytical
,,
16 data, nOm.r., m, 1.27-2.0, 8H; m, 3.22-4.12, 6H; s, 4.58,
- 17 lH
18 Step B: 5-hexyn-1-ol-tetrahydropyranyl ether
1 9 I~C_C~
Under a nitrogen atmosphere, and with stirring,
21 acetylene is introduced into dry tetrahydrofuran (150 ml.l,
22 cooled, and maintained below 10C., while butyl lithium
23 (150 ml. of a 2.4 M solution in hexane~ is added dropwise. ;
~ ., .
24 After addition is complete, the mixture is matured for one
25 hour. A passage of acetylene gas through the mixture is ;
26 steadily maintained. A solution of 4-chlorobutanol tetra-
. ;
~ 6~ 15996
1 hydropyranyl ether (50 g.) in dry hexamethyl phosphoric ~ -
2 triamide (250 ml.) is added dropwise at such a rate that
3 the temperature did not exceed 20C. The reaction mixture
4 is stirred overnight at room temperature; ice, then water~
is added to dilute the mixture to one litre, and the mix-
6 ture is extracted twice with ether. The ether solution is
backwashed with water, dried with potassium carbonate, and
8 evaporated under reduced pressure to pro~uce a residue con-
9 taining 5-hexyn~l-ol~tetrahydropyranyl ether. The residue
is distilled, collecting the fraction at 66-69C. (0.25 mm.
11 Hg.), containing principally 5-hexyn-1-ol-tetrahydropyranyl
12 ether, b.p. 67-G8C./0.25 mm. IIg. Gas chromatographic
13 analysis demonstrates that the product contains 5% unreacted
14 starting material--4-chlorobutanol tetrahydropyranyl ether.
Step C: 5-~exadecynyl-1-ol
16 CH3~CH2)9C_C(CH2)40H
17 Under a nitrogen atmosphere, and with stirring
1~ and cooling, butyl lithium (66 ml. of a 2.4 M solution in
19 hexane) is added to a solution of S-hexyl-l-ol-tetrahydro-
pyranyl ether (30 g.) in dry tetrahydrofuran (100 ml.),
21 ` at such a rate that the temperature remains below 10C.
22 The reaction mixture is stirred at 10C. for one hour,
23 then l-bromodecane (36.3 g.) in dry hexamethyl phosphonic
24 triamide (120 ml.) was added at a rate such that the tem-
perature is maintained below 25C. ~he reaction is stirred
26 at room temperature overnight under an atmosphere of nitro-
27 gen, then worked up by the addition of ice, then water, to
28 dilute the reaction to 700 ml., and is extracted twice with
29 ether. The combined ether extracts are washed several
times with water, dried over potassium carbonate, and
_g_ :
. . , : . - :
~ 7~8~ 15996
1 evaporated a-t reduced pressure. The residu~ is warmed at
2 50C. for two hours in methanol (200 ml.) containing p-
3 toluenesulfonic acid (250 m~). The methanolic solution is
4 reduced to a quarter its volume, 0.1 M sodium carbonate
solution (100 ml.) is added, and the mixture is extracted
6 with ether. The ether extract containing the product is
7 backwashed with 0.1 M sodium carbonate solution, then with
8 water, dried over magnesium sulfate, and evaporated under
9 reduced pressure. The low boiling material is mainly re-
moved by distillation at 0.1 mm. (~ 80C.), and the residue
11 is chromatographed on silica gel, eluting with hexane, then
12 hexane containing 3% ethyl acetate, containing 10~ ethyl
13 acetate and finally 20% ethyl acetate. The purified prod-
14 uct, 5-hexadecyl-1-ol, is characterized by n.m.r., CDC13
TMS, t, 3H, 0.88 ppm; m, 1.27, 16H; m, 1.6, 4H; m, 2.15,
16 4H; t, 3.63, 2H.
17 Step D: Hexadecane-5,5,6,6-d4-1-ol
18 CH3(cH2)9cD2(cH2)4
19 The hydroxyl group of 5-hexadecyl-1-ol is ex-
changed by washing an ethereal solution of the compound
2] several times with excess deuterium oxide. The recovered
22 5-hexadecyn-1-ol-OD ~16 g.) is dissolved in 500 ml. of dry,
23 oxygen-free toluene; and under an atmosphere of nitrogen,
24 tris-~triphenylphosphoro~rhodium chloride (0.5 g~) is added
as a catalyst. The acetylenic compound is reduced with D2
26 gas at 1 atmosphere pressure, taking up the calculated
27 volume of deuterium. The toluene solution is evaporated
28 under reduced pressure; the residue is extracted with ether
' .
--10--
' .
, , ' "' ' ' '." ' " ' ~ ' ''. ' ,' ' .~ ' , '
15996
&~
1 several times; and combined extracts are filtered and evap-
2 orated to dryness. The residue is distilled 125-128C.
3 (0.2 mm. Hg.), giving 14 g. of product.
4 Step E: Hexadecanal-5,5,6,6-d4
CH3(CH2)9CD2CD2(CH2)3CHO
6 In an appropriate flask fitted with a reflux
7 condensor is suspended 8.4 g. (86 mmole) of pyridinium
8 chlorochromate prepared as described in E. J. Corey and
9 J. William Suggs Tetrahedron Letters, p. 2647 (1975), in
100 ml. anhydrous methylene chloride. A solu-tion of
11 hexadecane-5,5,6,6-d4-1-ol (14 g., 57 mmole) in 20 ml.
12 methylene chloride is added in one portion to the stirred
13 solution. After 1.5 hours~ 100 ml. of dry ether is added
14 and the supernatant decanted from the black gum, which
separates from the reaction mixture. The insoluble resi-
16 due is then washed thoroughly three times with 50 ml.
17 portions of anhydrous ether; whereupon the insoluble black
18 gum residue becomes a black granular solid. The decanted
19 supernatant solution is combined with the ether extracts
;, .
containing the product and passed through a filter pad;
21 and the solvent is removed by distillation under reduced
22 pressure, leaving the product as a residual oil. The
23 product is purified by distillation at 115-120C. (0.15
24 mm.), thereby providing substantially pure hexadecanal-
5,5,6,6-d4, b.p. 115-120C./0.15 mm. Hg. The undistilled
26 residue comprising principally palmitoyl 5,5,6,6-d~-palmi-
27 tate 5,5,6,6-d4 is recycled by reduction of the ester with
28 lithium aluminum hydride in ether to the starting material,
29 hexadecanol-5,5,6,6-d4.
--11--
.. . ... . . .
. ' , ' , ' ' :
- l:)Y~
1 Step F: Palmitic-5,5,6,6-d Acid
2 CII3 (CH2) gCD2CD2 (CH2) 3COOH
3 To a stirred, cooled suspension of hexadecanal
4 5,5,6,6-d4 (7.5 g.) in 100 ml. of acetic acid is added,
dropwise, chromic acid l4.7 g.) in water (10 ml.) over a
6. period of 45 minutes. The temperature is maintained below
7 55C. The reaction is stirred for a further hour, diluted
8 with H2O to 500 ml., and extracted with ether (3 X 150 ml.)O
9 The combined ether extracts are washed with H2O (5 X 200
ml.), dried over magnesium sulfate, and evaporated. Resid-
11 ual acetic acid is removed by distillation with toluene.
12 The crude acid is purified by distillation 154-157C.
13 (0.15 mm.) and crystallization from petroleum ether (30-
14 60C.) at low temperature to a~ford substantially pure
palmitic-5,5,6,6-d4 acid, m.p. 63C (lit 63C. of the
16 corresponding light palmitlc acid). Mass spectrum
17 M+ = 260 (d4) = 96.95%, 259 (d3) = 3.05~; (98-98 atom ~O).
18 EXAMPLE 2
19 Palmitic 7,7,8,8-d4 Acid
;
20- Step A: 7-~exadecynoic Acid
.
21 CH3(CH2)7C-C(CH2)5COOH
22 A solution of l-decyne (14 g.) in dry tetrahydro-
23 furan (40 ml.) is cooled in an atmosp~ere of nitrogen to
24 < 0C. Butyllithium (45 ml. of 2.4 M solution) in hexane
is added at such a rate that the internal reaction tempera-
26 ture does not exceed 10C. When addition is complete, the
.,
. , .
- . . , : : . : ,., .. . . : ..
~ 7~ 15996
.
1 solution of l-lithiodecyne is matured for one hour at 5-
- 2 10C.; and the 6-bromo-hexanoic acid in 40 ml. o~ dry hexa-
; 3 methyl phosphonic triamide is added at a rate such that
4 the reaction does not go above 25C. After addition is
complete, the reaction is stirred at room temperature over-
6 night. The reaction mixture i5 diluted with iee and water,
I acidified to pH 2, and extracted with ether. The combined
8 ether extracts are backwashed with H20, dried over magnesium
9 sulfate, and evaporated under reduced pressure. The residue
containin~ the product is distilled. The Pirst ~raction
11 is reasonably pure, unreacted l-decyne (,-8 ~.), then the
12 temperature rises over a few minutes to 155C. at 0.1 mm.
13 The product is then recovered substantially pure as an oil.
14 Step B: Palmitic-7,7,8,8-d4 Acid
,
CII3(C~I2)7CD2CD2~CH2)5CH
:.- .
16 The 7-hexadecynoic acid is converted to the methyl
17 ester with methanol and hydrogen chloride. The ester is
18 reduced in a manner analogous to the reduction of 5-hexa-
., ~ .
' 19 decyn-ol as described in Example 1, Step D. The reeovered
methyl palmitate 7,7,8,8-d4 is converted to the acid by
21 hydrolysis with sodium hydroxide in aqueous methanol. The
22 acid is erystallized from petroleum ether at low tempera-
23 ture; m.p. 63-63C.
:
24 XAMPLE 3
~ 25 Palmitic 16,16,16-d3 Acid
.` '
- 26 Step A: 10-Undeeyn-l-ol tetrahydropyranyl ether
27 HC-C(CII2)90THP
28 10-undecynoic aeid is reduced with lithium
-13-
, :, - , . ~
-- ~ 15996
38~
1 aluminum hydride in ether, by standard procedures, to the
2 10-undecyn-1-ol. The 10-undecyn-1-ol is converted to its
3 tetrahydropyranyl ether by a method analo~ous to that des-
4 cribed above from 4-chlorobutanol (Example 1, Step A).
Step B: l-bromopentane 5,5,5-d3
6 CD3(CH2)~Br
7 Ethyl-2,2,2-d3 bromide (45 g.) is added dropwise
~ to a cooled, stirred suspension of Mg. (9.35 g.) in 200 ml.
9 of anhydrous ether. After the Griqnard reagent has formed,
trimethylene oxide (27 g.) in anhydrous ether ~60 ml.) i5
11 added over 2-3 minutes. The reaction mixture is refluxed
12 for one hour, then dry benzene is added slowly while the
13 ether is distilled out. After all ether has been replaced
14 with benzene, the reaction is refluxed for a further 3
hours. Saturated ammonium chloride solution is then added
16 slowly to the cooled reaction mixture. The mixture, after
17 acidification with hydrochloric acid solution, is extracted
18 with ether (4 X 100 ml.); the combined extracts are dried
19 over magnesium sulfate and evaporated under reduced pres-
sure until most of the ether is removed. The residue is
21 distilled through a vigreUx column, and two major ractions
22 are collected. The first at ~ 60C., thP second at 134-
23 140C. The second fraction is crude l-pentanol (14
24 A mixture of the above product, triphenylphos-
phene (45.2 g.), and dimethylformamide is treated with
26 bromine until the orange colour persists. The reaction
27 is stirred for a further hour, and the volatile material,
28 including dimethyl formamide, is removed under reduced
- ' .
- '.
-14-
15996
~7~
1 pressure. To the distillate is added H20 (oOO ml.). The
2 lower layer is carefully separated, backwashed twice with
3 water, dried over magnesium sulfate, and ~iltered. The
4 ma~nesium sulfate is extracted twice with ether, and the
combined washings and product layer are combined and dis-
6 tilled. Pure l-bromopentane 5,5,5-d3 is obtained. Single
7 peak by g.c.
8 Step C: 10-Hexadecyn-16,16,16-d301
9 CD3(CF12)4CgC(CH2)9-OH
Using 10-undecyn-1-ol tetrahydropyranyl ether
11 (34~5 g.) and l-bromopentane 5,5,5-d3 (35 g.), 10-hexa-
12 decyn-1-ol-16,16,16-d3 is prepared in a manner analogous
13 to that described for 5-hexadecyn-1-ol (Example 1, Step C).
14 The product is partially separated from the major impurity
10-undecyn-1-ol by column chromatography and used in the
16 next step without further purification.
17 Step D: Hexadecan-l-ol 16,16,16-d3
18 CD3(CH2)14CH2OH
19 The crude 10-hexadecyn-1-ol 16,16,16-d3 obtained
above is reduced with H2 in the presence of tris-(triphenyl-
21 phosphoro)-rhodium chloride as described for 5-hexadecyn-
22 l-ol. The crude recovered product is carefully distilled,
23 givin~ pure hexadecan-l-ol 16,16,16-d3; b.p. 115-118C./
24 0.15 mm. Hg.
-15-
,'` .
" 15996
7~
1 Step E:Palmitic 16,16,16~d3 Acid
2 CD3(CH2)14COO~
;'
3 The hexadecan-l-ol 16,16,16-d3 is oxidized in
4 two steps using pyridinium chlorochromate then chromic
acid in acetic acid as described for hexadecan-1-ol 5,5,
6- 6,6-d~ (Example 1, Steps E and F), to ~ive, after the same
7purification procedure, palmitic 16,16,16-d3 acid; m.p.,
63C-
9EXAMPLE 4
10Palmitic 11,11,12,12-d4 Acid
__ _
11 Step A:Pentadecan-l-ol 10,10,11,11-d4
12 CH3(CE~2)3CD2cD2(cH2)9
13 Pentadecan-l-ol 10,10,11,11-d4 is prepared in
14an exactly analogous manner to hexadecan-l-ol 16,16,16-d3
(described in Example 3), except l-bromobutane is used in
16 place of l-bromopentane 5,5,5-d3 and deuterium is used in
17 place of hydro~en in the reduction step.
,
18 Step B:l-Bromopentadecane 10,10,11,11-d4
.
19 CH3(CH2)3CD2cD2(cH2)9
Triphenylphosphine (11.3 q.) is added to a mix-
21ture of ether (80 ml.), carbon tetrabromide (14.3 ~.), and
22pentadecan-l-ol 10,10,11,11-d4; and the reaction mixture
23 is then refluxed. The progress of the reaction is moni-
2~ tored by gas chromatoqraphic analysis of aliquots taken
from the reaction mixture. After five hours, the reaction
'~ .
-16-
. ' ' :
. .
15996
~ I( sr;;J~ 5
1 is complete. Solvent is removed under reduced pressure,
2 and the residue filtered through a column of silica ~el,
3 eluting with hexane. The product is collected and distilled
4 to ~ive substantially pure l-bromopentadecane 10,10,11,11-d4
(~ 130C./0.2 mm. Hg.).
6 Step C: Hexadecanitrile 11,11,12,12-d4
7 CH3(CH2)3CD2cD2(cH2)9c
8 A mixture of 1-bromopentadecane 10,10,11,11-d4
9 (5.9 g.), potassium cyanide (2.6 g.), and ethanol (60 ml.)
are re~luxed. The reaction is monitored by t.l.c. (thin
11 layer chromatography). After refluxin~ overni~ht, the
12 reaction is complete. The reaction is cooled, evaporated
13 to a small volume, diluted with ether, and washed with
14 0.1 M sodium hydrogen carbonate solution, and extracted
with ether. The ether solution is dried and evaporated,
16 leaving hexadecanitrile 11,11,12,12-d4 as a product, which
17 is identified by n.m.r. CDC13, t, 3H, 0.8~; m, 1.28, 22H;
18 t, 2H, 2.30, and i.r. EC-D, 2090 cm 1, 2190 cm 1].
19 Step D: Palmitic-11,11,12,12-d Acid
2~ C~3(cH2)3cD2cD2(cH2)gCOOH
21 Hexadecanitrile 11,11,12,12-d4 (4.8 q.) is com-
22 bined with 20~ sodium hydroxide solution (20 ml.) and
23 ethanol ~100 ml.) and refluxed for 16 hours. All nitrile
24 is consumed by the procedure as demonstrated by t.l.c.
The mixture is carefully acidified with aqueous hydrochloric
26 acid. The ethanol is largely removed by evaporation at
27 reduced pressure, and the mixture is extracted with ether.
, . .
- 17-
15~96
.
1 The ether solution is washed once with water, dried over
2 magnesium sulfate, and evaporated. The acid product is
3 crystallized at low temperature from petroleum ether (30-
4 60C.), m.p. 62-63C.
'~'
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-18-
. . .
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