Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~12Z224
This invention relates to a process for the preparatio~ of
certain insecticidally-active esters of the so-called
"synthetic pyrethroid" type.
It is known, according to D.A.S. 2,231,312, that some
synthetic pyrethroids may be prepared by the reaction of a
s~bst~tuted cyclopropanecarbonyl halide with a 3-substituted
benzaldehyde in the presence of aqueous sodium or potassium
cyanide. Such a p~ocess yields pyrethroids of the following
type:-
/ \ CN
/ ~ COObH ~
The Applicant has found that yields of the ester of
the type depicted in formula I as well as other esters falling
within the "synthetic pyrethroid" field ~y be prepared more
efficiently and with higher yields by the use of a particular
catalyst.
Accordingly, the present invention provides a process
for the preparation of an ester of general formula:-
A
B.CO.O - CB ~ II
wherein R is an optionally-substituted alkyl or cycloalkyl group
and A is phenoxy, phenylthio or benzyl, which comprises reacting
li22~24
3 -
a benzaldehyde ~f the formula:-
A
OCH ~ III
with an acyl halide of the formula R.CO.Hal (wherein Hal is
bromide or chloride) in the presence of water, a water-
soluble cyanide, a substantially water-immiscible aprotic
~olvent and a phase transfer catalyst.
The phase transfer catalyst may be any reagent which
is capab~ of accelerating interphase reactions in aqueous/
organic two-phase systems.
The phase transfer catalyst may be an onium compound,
particularly a ~uaternary onium compound of the general formula
Rl +
R2_x_R4 Y
R3
wherein X represents a nitrogen, phocphorus or arsenic atom,
Rl, R2, R3 and R4 each an al~yl, aralkyl, alkaryl or aryl group
and Y a monovalent ion, e.g. a halide such as chloride, bromi~e or
iodide, or an alkylsulphate such a~ methylsulphate or ethylsulphate
or a ~ulphonium compound of the general formula
r R6 1 +
L R5-S_R7 ~ y_
wherein R5, R6 and R7 each represent an alkyl group and
Y a monovalent ion, e.g. a halide such as chloride, bromide
~22Z24
-- 4 --
or iodide, or an alkylsulphate such as methylsulphate or
ethylsulphate. Preferably the alkyl groups contain l to 18
carbon atoms and the aralkyl and alkaryl groups contain up to
lO carbon atoms; the aryl group is preferably phenyl.
Examples of suitable onium compounds are tetra-n-
butylammonium bromide, tetra-n-butylammonium chloride,
methyltri-2-methylphenyl-ammonium chloride, tetramethyl-
phosphonium iodide, tetra-n-butylphosphonium bromide,
methyltriphenylarsonium iodide, ethyl-2-methylpentadecyl-
2-methyl~ndecylsulphonium ethylsulphate, methyldinonyl-
sulphonium methylsulphate and n-hexadecyldimethylsulphonium
iodide. Very good results have been obtained with quaternary
ammonium compound~.
The onium compound may be a hydroxide or a salt and
can be employed as the functional portion of a strongly-
basic anion exchange resin having a structural portion
(polymer matrix) and a functional portion (ion-active group).
Of special importance are ~olystyrene resins, such as copolymers
o~ aromatic monovinyl compounds and aromatic polyvinyl compounds,
particularly styrene/divinylbenzene copolymers. The
fun~tional portion is a quaternary ammonium, phosphonium or
arsonium group. Examples of strongly-basic anion exchange
resins which may be employed are those derived from
trimethylamine (such as the products known under the trade
names of "Amberlite IRA-400", "Amberlite IRA-401",
'Amberlite IRA-402", "Amberlite IRA-900", "Duolite A-lOl-D",
"Duolite ES-lll", "Dowex l", Dowex ll", "Dowex 21K" and
"Ionac A-450"), and those derived frorr dimethylethanol-
amine (such as the products 3cnown under the trade names of
"Amberlite IRA-4lO", "Amberlite IRA-9ll", "Dowex 2",
"Duolite A-102-D", "Ionac A-542" and "Ionac A-550").
iiZ2224
Very good results have been obtained with those derived
from tr-methylamine.
Other suitable phase transfer catalysts are macrocyclic
polyethers known as "cro~n ethers". These compounds,
together with their preparation, are described in the
literature, for example in Tetrahedron Letters No.
18(1972) pp. 1793-1796, and are commonly designated by
reference to the total number of atoms forming the macro-
cyclic ring together with the number of oxygen atoms
in that ring. Thus the macrocyclic polyether whose formal
chemical name is 1,4,7,10,13,16-hexaoxacyclooctadecane is
designated as "18-crown-6". Other examples of suitable
macrocyclic polyethers are 3,4-benzo-1,6,9,12,15,18,21-
heptaoxacyclotricos-3ene and 3,4-benzo-1,6,~,12,-tetra-
oxacyclotetradec-3-ene. 18-Crown-6 is particularly suit~ble.
Other suitable phase transfer catalysts are surface-
active agents. A "~urface-active agent" is defined as in
Kirk-Othmer, "Encyclopedia of Chemical Technology",
second edition, volume 19(1969), page 508: "An organic
compound that encompasses in the same molecule two dissimilar
structural groups, one being water-soluble and one being
water-insoluble".
The surface-active agent is preferably non-ionic,
such as a poly(alkyleneoxy) derivative formed by reacting a higher
alcohol, alkylphenol or ~atty acid with ethylene oxide or
propylene oxide. Suitable alcohols, alkylphenols or fatty acids
112Z224
-- 6 --
contain an alky' group of 8-20 carbon atoms and the number
Or alkyleneoxy units is in the range of 1-50. A particularly
suitable non-ionic surface-active agent (referred to in the
examples as "Dobanol 91-6") is formed from a Cg-Cll n-alkanol
mixture and contains an average of six ethyleneoxy units. The
non-ionic surface-active agent may be an alkylbenzene containing
a straight alkyl group. Suitable alkylbenzenes contain an
alkyl group of 8-20 carbon atoms.
The molar ~atio of the amount of phase transfer
catalyst to the amount of benzaldehyde of the general formula
III may vary within wide limits, but~ is suitably from
1:5 to 1:500. The use of low molar ratios will require a longer
time to complete th~ reaction, whilst the u~e of higher molar
ratios naturally increases the cost to produce a given quantity
of eæter. Thus, the choice of reaction time and molar ratio
catalyst to benzaldehyde are mutually interdependent, and in
any individual instance will depend on the local economic
factors. Very good results are usually obtained at molar ratios
from 1:10 to 1:100.
Another advantage of the process according to the present
invention is that the molar ratio of the amount of acyl halide
(R.CO.Hal) to the amount of benzaldehyde is 1:1 or slightly
in excess thereof. This molar ratio is preferably in the
range of from 1,1:1.0 to 1,0:1Ø
The mQlar ratio of the amount of water-soluble cyanide
to the amount of aromatic aldehyde is suitably from
1~2~224
1.5:1 to 1.0:1.0 and preferably from 1.3:1 to 1.02:1.00.
By "water-soluble cyanide" is meant a water-soluble salt of
hydrogen cyanide, Of the water-sc,luble cyanides alkali-
metal cyanides and alkaline-earth-metal cyanides are
preferred. Sodium cyanide is particularly preferred, because
it affords the esters of the general formula II in the
shortest reaction time.
The temperature at which the process is conducted
is suitably above 0C and is preferably in the range 10C
1~ to 50C. Very good results have been obtained at temperatures
in the range 15 C to 40C. The process has the advantage
that ambient tempera~ures are very suitable.
Examples of suitable substantially water-immiscible
aprotic solvents are alkanes or cycloalkanes or a mixture
thereof; particular examples being n-hexane, n-heptane, n-
octane, n-nonane, n-decane and their isomers (for example
2-methylpentane, 3-methylpentane, 2-methylhexane, 3-methyl-
hexane and 2,4,4-trimethylpentane) and cyclohexane and
methylcyclohexane. Gasolines rich in alkanes are also very
suitable, for example with a boiling range at atmospheric
pressure between 40 and 65C, 60 and 80C or 80 and 110C.
Very good results have been obtained with n-heptane and cyclo-
hexane.
Other very suitable substantially water-immiscible
aprotic solvents are aromatic hydrocarbons and chlorinated
hydrocarbons, for example benzene, toluene, o-, m- and
~122224
-- 8 --
~-xylene, the trimethylbenzenes, dichloromethane, 1,2-di-
chloromethane, chloroform, monochlorobenzene and 1,2-
and 1,3-dichlorobenzene, Very good results have been
obtained with toluene and xylene.
The process according to the present invention may be
conducted start.ing from unsaturated or saturated aqueous
solutions of water-soluble cyanide and, in the latter case
n the presence or absence o~ solid water-soluble cyanide.
~ith some solvents it has been found that the pres~nce
of solid water-soluble cyanide improves the yield and
reaction time.
The use of alkanes or cycloalkanes in combination
with aqueous solutions of cyanide in the absence of
solid water-soluble cyanide enables the reaction time
to be kept to a minimum. The use of aromatic hydro-
carbons or chlorinated hydrocarbons in combination
with aqueous solutions of cyanide in the absence of
solid water-soluble cyanide produces slightly longer
reaction times but nevertheless is sometimes pre~erred
becau~e the resulting reaction mixture can be used
directly for pesticidal formulations without further
separation of the ester from the solvent. The use
of aromatic hydrocarbons and chlorinated hydrocarbons
in combination with solid water-soluble cyanide.
2~ produces short reaction times. Solid water-soluble
112~224
g
cyanide may however also be used in the presence of
(cyclo)alkanes.
Useful reaction times can be obtained when molar
ratios of the amount of water to the total amount of
water-soluble cyanide is higher than 0.05.
Other examples Gf substantially water-immiscible
aprotic solvents are dialkyl ethers and substantially
water-immiscible alkanones, for example di~thyl ether,
diisopropyl ether and diisobutyl ketone. Mixtures of
solvents, for example of alkanes and aromatic hydrocarbons
may be employed for example of n-heptane containing up to
10% by weight of benzene and/or toluene.
The group A in the general formula II is preferably
phenoxy because this substituent gives rise to the most
active form of the pyrethroid pesticides.
The group R in the general formula RC(O)Hal is defined
as an optionally-substituted alkyl or cycloalkyl ~roup. The
alkyl group may be straight or branched and preferably contains
up to 10 carbon atoms. The alkyl groups preferably have
a tertiary or quaternary carbon atom bound to the group -C(O)Hal.
Examples of such alkanoyl halides are 2-methylpropanoyl
chloride, 2,2-dimethylpropanoyl chloride and 2-methylbutanoyl
bromide. Very good results have been obtained with 2-methyl-
propanoyl chloride. The alkyl group may carry as substituents,
for example, hydrocarbyloxy or substituted phenyl groups,
e.g. a halophenyl group. Very good results have been obtained
-- 1 0
with 1-(4-chlorophenyl)-2-methylpropyl groups. The cycloalkyl
group itself preferably contains 3 to ~ carbon atoms and has as
optiona~- ~ubstituents a group or groups selected from alkyl,
alkenyl, haloalkenyl each of which suitably contains up to
8 carbon atoms. Examples of cycloalkyl groups are cyclopropyl,
cyclobutyl and cyclohexyl groups. Very good results have
been obtained with optionally substituted cyclopropanecarbonyl
halides, particularly with 2,2,3,3-tetramethylcyclo-
propanecarbonyl halides and 2-(2,2-dichlorovinyl)-3,3-di-
10 methylcyclopropanecarbonyl halides. The latter halides
may have a cis or trans structure or may be a mixture of
such structures and may be a pure optical isomer or a mixture
of optical isomers.
The substituent Hal in the general formula RC(O)Hal
15 is preferably a chlorine or bromine atom and in particular
a chlorine atom;
The process according to the invention may be carried
out by gradual addition of the acyl halide to a mixture,
preferably a stirred mixture, of the other starting compounds
20 (particularly advan~geous when R in the general formula
RC(O)Hal represents a 2,2,3,3-tetramethylcyclop~opyl group
a 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropyl group,
or a 1-(4-chlorophenyl)-2-methylpropyl group. Alternati~ely
the to~al amounts of the starting materials may be placed
25 together and the reaction allowed to take place with
11222Z4
-- 11 --
vigorous stirring of the reaction mixture.
The process is of particular interest when the aromatic
aldehyde is 3-phenoxybenzaldehyde and the acyl halide is
2-(4-chlorophenyl)-3-methylbutanoyl chloride, 2,2,3,3-tetra-
methylcyclopropanecarbonyl chloride or 2-(2,2-dichloro-
vinyl)-3,3-dimethylcyclopropanecarbonyl chloride, because
the esters then formed, a-cyano-3-phenoxybenzyl 2-(4-chloro-
phenyl)-3-methy_butanoate, ~-cyano-3-phenoxybenzyl 2,2,3,3-
tetramethylcycloprbpanecarboxylate and -cyano-3-phenoxy-
benzyl 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropanecarboxy-
late, respectively, are especially active pesticidal compounds.
The Exam~les further illustrate the invention. All
experiments were conducted at a temperature of 23C The
reaction mixtures were stirred vigorously and analysed
by gas-liquid chromatography to determine the yield of
the ester formed. Reaction mixtures were filtered to remove pre-
cipitated sodium chloride and solid sodium cyanide, if any,
and drying of solutions was carried out over anhydrous sodium
sulphate. Flaæhing of the solvent took place in a eilm
evaporator at a pressure of 15 mm Hg. All yields are calcu-
lated on starting aromatic aldehyde~
EXAMPLE I
Pre~aration of ~-cyano-3-~henox~benz~l 2-(4-chloro~hen~
___ ______________ ____ _ _____ ____ ____ ________ ___ _ _ __
meth~abutanoate in the ~resence of n-he~tane
~122~24
- 12 -
A 50 ml round-bottomed flask equippe~ with a magnetic
stirrer was charged with 10 mmol of 3-phenoxybenzaldehyde,
10 mmol of 2-(4-chlorophenyl)-3-methylbutanoyl chloride, 12 mmol
o~ sodium cyanide, water, a cataiyst, if any, and 20 ml of
n-heptane and the mixture thus formed was stirred. Seven experi-
ments were carried Out in this manner, see Table I.
Table I
1 2 ~ 4 ~ 6
Exp. __ CataI~st Water Reaction time, Yield of ester,
no. ~ame ~mount added h %
%mol on ml
____ ______________ aadeh~d_ ____
) _ _ 1.0 3 86
18 more than 99
2 methyl-tri-2- 5 1.0 2 96
methyl-heptyl-
ammonium chloride
3 tetra-n-butylsmmo- 2 1.0 5 99
niumch~oride
4 ditto 2 2.0 5 99
tetra-n-butyl- 2 1.0 3 99
phosphonium bromide
6 n-hexadecyld~ethyl 2 1.0 3 97
cUlp~nium iodide
7 1,4,7,10,13,16- 2 1.0 3 94
hexaoxacyclooctadecane
_________________________________________________________________
1) not according to the invention.
Column 1 in Table I states the number of the experiment,
column 2 the catalyst, column 4 the amount of water added to
the starting mixture (excluding the water present in the sodium
cyanide) and column 5 the reaction time. The yield of the
1~2~:~24
- 13 -
~esired ester is presented in column 6. The sodium
cyanide was completely dissolved.
EXAMPLE II
Pre~ara_ic,n_of__c~ano-~-~henox~benz~l 2-(2l2-dichloro-
v_n~ -dimeth~ac~cao~ro~anecarbox~la e_in the_~re_en_e
of n-he~tane
__ _____ ___ _
A 50 ml round-bottomed flask equipped with a magnetic
stirrer was charged with 10 mmol of 3-phenoxybenzaldehyde,
an amount of 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropanecar-
bonyl chloride, 12 mmol of sodium cyanide, water, a catalyst,
if any and 20 mi of n-heptane The mixture thus formed was
stirred. Six experiments were carried out in this manner,
see Table II. Column 3,4 and 5 state the amounts of cata-
lyst~ water and acyl chloride added. The yield of the
desired ester is presented in column 7.
~12Z224
Table II
1 2 3 4 5 6 7
_______________________________________________________________
E Catalyst Water Acyl Reaction Yield of
P -------_____-_ ----- added chloride, time, ester, %
no. name ~mount ml mmol h
%mol on
___ ___________ _aad_h~de ____ ________ _______ _________
1)
1 - - 1.0 10.2 3 49
21 94
44 99
2 methyl-tri-2 5 1.0 10.2 1 96
m~thyl~eptyl-
ammonium chloride
3 tet~a-n-butyl- 2 1.0 10.5 1 90
Ammonium chloride
4 99
4 Amb2e~1ite IRA '(1 gram)l.0 10,5 5 95
400 J
Dobanol 91-63) 2 1.0 10.0 2 80
6 1,4,7,10,13,16- 2 1.0 10.0 2 76
~5 hexaoxacycloocta-
decane
____________________ ________________________________________
1) not according to the invention
2) a trade mark for a strongly basic anion exchange resin
having a styrene/divinylbenzene copolymer as polymer matrix
and a quaternary ammonium group as ion-active group.
The chloride form was used.
3) a trade mark for a non-ionic surface-active agent formed
from a C9-Cll alcohol mixture and containing an a~erage
of 6 ethyleneoxy units, the alcohol mixture consists oP 85%
n-alkanols and 15g 2-alkylalkanols.
1122224
- 15 -
EXAMPLE III
Pre~arat_on_Qf -c~ano-3-~henox~benz~l 2~2~3-tetrameth~l-
c~vclopro~anecarbox~late in the ~resence of n-he~tane.
___ __ _________ ____________ _______________ ____
Methods A and B as indicated below were employed
to prepare this ester. This example demonstrates that a
gradual addition of the acid chloride to the reaction
mixture during a period of 0.5 t~ 2 hours produces
marked increases in yield at the end of that period.
Method A
A 50 ml round-bottomed flask equipped with a magneti~
stirrer was charged with 10 mmol of 3-phenoxybenzaldehyde,
10 mmol of 2,2,3,3-tetramethylcyclopropanecarbonyl chloride,
12 mmol of sodium cyanide, 1.00 ml of uater, a catalyst, if
any, and 20 ml of n-heptane. The molar ratio of water to NaCN
was 4.64, solid NaCN being absent. The catalyst was added
in an amount of 0.20 m~ol. The nixture thus formed was
stirred for 1.5 hours and analysed.
Method B (gradual addition of acid chloride)
The flask use~ for method A was charged with 10 mmol
of 3-phenoxybenzaldehyde, 12 mmol of sodium cyanide,
10 ml of n-heptane, 1.00 ml of water and 0.20 m~ol of a
catalyst, if any, the molar ratio of water to NaCN being 4.64.
An amount of 10 mmol of 2,2,3,3-tetramethylcyclopropane-
carbonyl chloride dissolved in 10 ml of n-heptane was
introduced into the flask during a period of 70-75 min.
The yield of the ester was determined at the end of this
period.
112Z;~2~
Five experiments were carried out in this manner.
Table III states the catalysts u,ed, if any. This Table al~o
presents the yield of the desired ester.
Table III
Exp. Catalyst Yield of ester, %
no. Method A Method B
______________________________ ________ _________
l*) none 17 40
21,4,7,10,13,16-hexaoxa- 18 97
cyclooctadecane
3 tetra-n-butylammonium chloride 20 98
4 methyl-t~i-2-methylheptyl- 18 96
ammonium chloride
Dobanol 91-6 ) 44 98
______________________________________________________
not according to the invention
) for explanation of this word, see Table II.
The amounts of the catalysts used were 2%m in the
experiments 2-4 and 10 %m in experiment 5, calculated on
3-phenoxybenzaldehyde.
The reaction mixture obtained in experiment 4, method
B, was filtered and the filtrate washed twice with 20 ml of a
1 M aqueous solution of sodium bicarbonate and once with
20 ml of water. The washed filtrate was dried and the n-hep-
tane was flashed from the dried filtrate to obtain the ester as
a pale yellow oil. This oil was dissolved in 2.5 ml of methanol
at 23 C and the solution obtained was cooled to a temperature
1122Z24
-- 17 --
of ~0C to give a precipitate of the ester. The ester was
filtered and had a purity of more than 98%.
EXAMPLE IV
Pre~aration of ~-c2ano-3-~henoxybenzyl 2-~4-chloro~hen~1)-3-
meth~lbutanoate on an enlarged s_aae
Methods A (not according to the invention), B and C were
compared for the preparation of the desiréd ester.
Method Al in the absence of a phase transfer catalyst.
A 500 ml round-bottomed flask equipped with a paddle
stirrer was charged with 100 mmol of 3-phenoxybenzaldehyde, 100
mmol of 2-(4-chlorophenyl)-3-methylbutanoyl chloride, 120 mmol of
sodium cyanide, 10 ml of water (which dissolved all sodium
cyanide) and 200 ml of n-heptane. After stirring for 45 hours
the mixture was warmed to a temperature between 40 and 50C
and filtered. The filtrate was washed twice with 50 ml of a
1 M aqueous sodium bicarbonate solution, once with 50 ml of water,
dried and the n-heptane was flashed from the dried solution to
give the desired ester in a yield of 99% and a purity of 96%.
Mehod_B, in the presence of an onium compound.
The experiment ciescribed in section A of this example was
repeated in the presence of 2 %m of tetra-n-butylammonium chloride,
calculated on 3-phenoxybenzaldehyde. After two hours the ester
was obtained in a yield of 99% with a purity of 94%.
Method C, in the presence of a non-ionic surface-active agent.
2~ The experiment described in section A of this Example was
repeated in the presence of 10 %m of "Dobanol 91-6" ( for meaning
il22224
- 18 -
of this word, see Table II), calculated on 3-phenoxybenzaldehyde.
After three hours' stirring the reaction mixture was warmed to
a temperature between 40 and 50C and filtered. An amount
of 50 ml of ethanol was added (to break the emulsion for~ed)
tG the filtrate and the filtrate was washed twice with 50
ml of a 1 M aqueous solution of sodium bicarbonate, once with
50 ml of water, d~ied and the n-heptane was flashed from the dried
solution to give the ester in a yield of 98% and a purity of
97%.
The above results are summarised in the following Table
IV.
Table IV
Exp. Catal~st Reaction yield of Purity of
no. time, h ester, % ester, %
name amoUn~ ol
on aldehyde_ ________ ________ ___._____
1 none - 45 99 96
2 tetra-n-butylammo- 2 2 99 94
~ium c~loridel
3 Dobanol 91-6 ) 10 3 98 97
_______________________________________________________________
1) for explanation of this word, see Table II.
EXAMPLE V
Pr_~ara_ion_gf_a-c~ano_~_~henoxybenzyl 2-(4-chloro~hen~l)__
~-m_th~lbu anoate_in_th__~resenc~ of_various solvents and
_glid__~an_de
A 50 ml round-bottomed flask equipped with a magnetic
stirrer was charged with 10 mmol of 3-phenoxybenzaldehyde,
10.0 or 10.5 mmol of 2-(4-chlorophenyl)-3-methylbutanoyl
1~222~4
-- 19 --
chloride, 12 mmol of sodium cyanide, 0.02 ml of water and 20 ml
of an aprotic solvent. The molar ratio of water to sodium
cyanide was 0.105, solid NaCN being present. The reaction mixture
was stirred and analysed. Thirteen experiments were conducted
in this manner, see Table V, stating which solvents were used.
Experiments 2,3,4,8 and 9 were conducted with 10.0 and the
other experiments with 10.5 mmol of 2-(4-chlorophenyl)-3-
methylbutanoyl chloride. The petroleum ether used in experiment
3 consisted of 97% by weight of alkanes and 3% by weight of
benzene and had a boiling range at atmospheric pressure between
62 and 82C. The ester remained in solution during the reaction
in experiments 3 and 4. The reaction mixture obtained in ex-
periment 4 was fiitered and the cyclohexane was flashed from
the filtrate to give the ester wanted as a colourless oil
in ~uantitative yield. Table V also presents the yields of
the desired ester. Comparison of the yields shows that the
alkanes and cyclohexane are the best solvents.
112Z224
- 20 -
Table V
Experiment Solvent Reaction time, Yield of ester,
no h %
______ ___ ___________________ ______________ _______________
1 n-heptane 1.0 more than 99
2 2,4,4-trimethylpentane 1 92
2 99
3 petroleum ether 1 91
2 99
4 cyclohexane 1 80
3 more than 99
toluene 3 38
24 98
6 dichloromethane 2 34
18 46
7 o-dichlorobenzene 2 59
18 72
8 diethyl ether 3 54
91
9 diisobutyl ketone 20 80
nitromethane 5 5
21 13
11 1,4-dioxane 18 0
12 N,N-dimethylformamide 5 5
21 7
13 dimethylsulp~xide 2
18 0
_______________________________________________________________
~122Z24
- 21 -
EXAMPLE VI
Pre~aration of ~-cyano-~-~henox~enz~l 2-(4-chloro~hen~l)-
___ ______________ ____ _ _____ ____ ____ ________ ___ _ _
~-meth~1butanoate in the ~resence of soaid c~anide
~ 50 ml round-bottomed flask equipped with a magnetic
stirrer was charged with 10 mmol of 3-phenoxybenzaldehyde, 10.5
mmol of 2-(4-chlorophenyl)-3-methylbutanoyl chloride, 12 mmol
of sodium cyanide, 20 ml of toluene, a phase trans~er catalyst,
and water. The mixture thus ~ormed was stirred for varying
periods of time and subsequently analysed. Six experiments
were conducted in this manner, and the results are shown in
Table VI, stating which catalysts and how much water was added,
i~ any. The catalysts were employed in an amount of 0.20 mmol.
Table VI
1 2 3 4 5 6
___________________________________________________________________
Exp~ Catalyst Water Molar ratio Reaction Yield o~
no. added water to time, h ester, %
ml NaCN
___ _____________________ ________________________ _________
1 1,4,7,10,13,16-he- - 0.012 2 60
xaoxacyclooctadecane 20 91
97
2 ditto 0.02 0.105 3 100
3 ditto 1.00 4.64 2 95
4 98
100
4 tetra-n-butylammonium 0.012 2 30
bromide 22 32
ditto 0.~2 0.105 2 81
18 98
6 ditto 1.00* 4.64 2 71
22 81
_________________________________________________________________
For the sake of comparison these 2 experiments had no solid
cyanide present.
~122Z24
- 22 -
The sodium cyanide used consisted of particles having
a largest dimension of 0.5 mm and contained ~.44% by weight
of water. The molar ratio of water to sodium cyanide has been
caleulatec~ taking into account the water present in the
sodium cyanide and the water added, if any. ~or comparison
it may be stated th~t the molar ratio of water to sodium
cyanide in a saturated aqueous solution of sodium cyanide
having a temperature of 23C is 4.1.
