TRADUCTION NON-DISPONIBLE

PREPARATION OF ESTERS OF THIOCARBAMIC ACIDS INVOLVING USE OF PHASE TRANSFER CATALYSTS

Abrégé anglais

\
Abstract of the Disclosure
Ester of thiocarbamic acids are prepared
by a process comprising (a) reacting a carbamyl
chloride with a mercaptan in the presence of
(i) an aqueous solution of a caustic agent,
and (ii) a catalytic amount of a phase transfer
catalyst; (b) separating the organic ant aqueous
phases; and (c) recovering the thiocarbamic acid
enter from the organic phase

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A process for the preparation of a thiocarbamic acid
ester which comprises:
(a) reacting a carbamyl chloride of the formula
<IMG>
in which
R1 and R2 are independently selected from the group
consisting of hydrogen and the following substituted
or unsubstituted groups: C1-C12 alkyl, C2-C8 alkenyl,
C3-C6 alkynyl, phenyl, C7-C10 phenylalkyl, C3-C7
cycloalkyl, C5-C7 cycloalkenyl, C1-C8 alkoxy, C2-C8
alkenoxy, C2-C8 alkoxyalkyl, C2-C8 alkylthioalkyl,
C3-C8 alkoxyalkenyl and C3-C8 alkylthioalkenyl;
wherein the substituents are independently selected
from the group consisting of halo, cyano, nitro,
trifluoromethyl, and alkoxy and alkyl having 1 to 4
carbon atoms; or
R1 and R2 together with the nitrogen atom to which they
are bound form a member selected from the group con-
sisting of pyrryl, pyridyl, and C2-C6 polyalkylene-
imine;
with a mercaptan having the formula R3SH, in which R3 is
selected from the group consisting of the following sub-
stituted or unsubstituted groups:
C1-C12 alkyl, C2-C8 alkenyl, C3-C6 alkynyl, phenyl,
C7-C10 phenylalkyl, C3-C7 cycloalkyl, C5-C7 cycloalkenyl,
C1-C8 alkoxy, C2-C8 alkenoxy, C2-C8 alkoxyalkyl, C2-C8
alkylthioalkyl, C3-C8 alkoxyalkenyl and C3-C8 alkylthio-
24

alkenyl; wherein the substituents are independently
selected from the group consisting of halo, cyano, nitro,
trifluoromethyl, C1-C4 alkyl, and C1-C4 alkoxy;
in the presence of
(i) an aqueous solution comprising of from 5 to 50%
by weight of an alkali or alkaline earth metal
hydroxide, and
(ii) a catalytic amount of a quaternary salt having
the formula
(R4R5R6R7M)+Q-
in which:
M is a member selected from the group consisting
of nitrogen, phosphorus, and arsenic;
Q- is an anion selected from the group consisting
of chloride, bromide, iodide, and hydroxide; and
R4, R5, R6, and R7 are independently selected
from the group consisting C1-C25 alkyl, C2-C25
alkenyl, phenyl, C7-C10 alkylphenyl, C7-C10
phenylalkyl, and C4-C8 cycloalkyl; or any two
of the groups R4, R5, R6 and R7 are joined to
constitute a 5- or 6-membered heterocyclic
ring containing the quaternized M atom plus a
maximum of one non-adjacent nitrogen, oxygen,
or sulfur atom; and
(b) separating said ester from said aqueous solution.
2. A process for the preparation of a thiocarbamic acid
ester which comprises:
(a) reacting a carbamyl chloride having the formula
<IMG>

in which R1 and R2 are independently selected from the
group consisting of Cl-C6 alkyl and C5-C7 cycloalkyl, or
R1 and R2 together with the nitrogen atom to which they
are bound from C4-C6 polyalkyleneimine,
with a mercaptan having the formula R3SH in which R3 is
selected from the group consisting of C1-C6 alkyl, phenyl,
halo-substituted phenyl, benzyl, and halo-substituted
benzyl,
in the presence of,
(i) an aqueous solution comprising of from 5 to 50%
by weight of a caustic agent selected from the
group consisting of NaOH, KOH, and Ba(OH)2, and
(ii) a catalytic amount of a quaternary salt having
the formula (R4R5R6R7M)+Q- in which
R4, R5, R6, and R7 are independently selected
from the group consisting of C1-C25 alkyl, phenyl,
and C7-C10 phenylalkyl,
M is nitrogen or phosphorus, and
Q- is chloride or bromide; and
(b) separating said ester from said aqueous solution.
3. The process of Claim 2 in which the quaternary salt
is selected from the group consisting of tetra-n-butylphosphonium
chloride, hexadecyltributylphosphonium bromide, benzyltriethyl-
ammonium chloride, benzyltriethylammonium bromide, tricaprylyl-
methylammonium chloride, and dimethyldicocoammonium chloride.
4. The process of Claim 2 in which the quaternary salt
is selected from the group consisting of tetra-n-butylphosphonium
chloride, benzyltriethylammonium chloride, tricaprylylmethyl-
ammonium chloride, and dimethyldicocoammonium chloride.
26

5. The process of Claim 2 in which the quaternary salt
of step (a)(ii) is present in an amount ranging from about 0.2 to
about 5.0 weight %.
6. The process of Claim 2 in which the quaternary salt
of step (a)(ii) is present in an amount ranging from about 0.5 to
about 1.0 weight %.
7. The process of Claim 2 in which the reaction of step
(a) occurs at a temperature from about 10°C to about 100°C.
8. The process of Claim 2 in which the reaction of step
(a) occurs at a temperature from about 20°C to about 80°C.
9. The process of Claim 2 in which the mole ratio of
mercaptan to carbamyl chloride in step (a) is at least about 1Ø
10. The process of Claim 2 in which the mole ratio of
mercaptan to carbamyl chloride in step (a) is at least about 1.1.
11. The process of Claim 2 in which the caustic agent of
step (a)(i) is sodium hydroxide.
12. The process of Claim 2 in which the mole ratio of
caustic agent to mercaptan in step (a) is at least about 0.5.
13. The process of Claim 2 in which the mole ratio of
caustic agent to mercaptan in step (a) is at least about 1Ø
14. The process of Claim 2 in which the concentration of
the caustic solution of step (a)(i) ranges from about 5% to about
50% by weight.
15. The process of Claim 2 in which the concentration of
the caustic solution to step (a)(i) ranges from about 10% to
about 30% by weight.
16. The process of Claim 2 in which said carbamyl
chloride is di-n-propylcarbamyl chloride, said mercaptan is ethyl
mercaptan, and said quaternary salt is tricaprylylmethylammonium
chloride.
27

17. The process of Claim 2 in which said carbamyl chlo-
ride is diisobutylcarbamyl chloride, said mercaptan is ethyl
mercaptan, and said quaternary salt is tricaprylylmethylammonium
chloride.
18. The process of Claim 2 in which said carbamyl chlo-
ride is di-n-propylcarbamyl chloride, said mercaptan is n-propyl
mercaptan, and said quaternary salt is tricaprylylmethylammonium
chloride or dimethyldicocoammonium chloride.
19. The process of Claim 2 in which said carbamyl chlo-
ride is cyclohexyl ethylcarbam-1 chloride, said mercaptan is
ethylmercaptan, and said quaternary salt is tricaprylylmethyl-
ammonium chloride.
20. The process of Claim 2 in which said carbamyl chlo-
ride is n-butylethylcarbamyl chloride, said mercaptan is n-propyl
mercaptan, and said quaternary salt is tricaprylylmethylammonium
chloride.
21. The process of Claim 2 in which said carbamyl chlo-
ride is hexahydro-1H-azepine-1 carbamyl chloride, said mercaptan
is p-chlorophenyl mercaptan, and said quaternary salt is tri-
caprylylemethylammonium chloride.
22. The process of Claim 2 in which said carbamyl chlo-
ride is hexahydro-1H-azepine-1 carbamyl chloride, said mercaptan
is ethyl mercaptan, and said quaternary salt is tricaprylyl-
methylammonium chloride.
23. The process of Claim 2 in which said carbamyl chlo-
ride is cyclohexyl ethylcarbamyl chloride, said mercaptan is
benzyl mercaptan, and said quaternary salt is tricaprylylmethyl-
ammonium chloride or dimethyldicocoammonium chloride.
24. A process for the preparation of a thiocarbamic
acid ester which comprises:
(a) reacting a carbamyl chloride having the formula
28

<IMG>
in which R1 and R2 are independently selected from the
group consisting of C1-C6 alkyl and C5-C7 cycloalkyl, or
R1 and R2 together with the nitrogen atom to which they
are bound from C4-C6 polyalkyleneimine,
with a mercaptan having the formula R3SH in which R3 is
selected from the group consisting of C1-C6 alkyl, phenyl,
halo-substituted phenyl, benzyl, and halo-substituted
benzyl,
in the presence of,
(i) an aqueous solution of a member selected from the
group consisting of NaOH, KOH, and Ba(OH)2, and
(ii) a catalytic amount of a quaternary salt having
the formula (R4R5R6R7M)+Q- in which
R , R , R6, and R7 are independently selected from
the group consisting of C1-C10 alkyl, phenyl, and
C7-C10 phenylalkyl, and have a total sum of 10 to
16 carbon atoms,
M is nitrogen or phosphorus, and
Q- is chloride or bromide; and
(b) separating said ester from said aqueous solution.
25. The process of Claim 24 in which said carbamyl chlo-
ride is di-n-propylcarbamyl chloride, said mercaptan is n-propyl
mercaptan, and said quaternary salt is tetra-n-butylphosphonium
chloride or benzyltriethylammonium chloride.
26. The process of Claim 24 in which said carbamyl
chloride is hexahydro-1H-azepine-1 carbamyl chloride, said mer-
captan is ethyl mercaptan, and said quaternary salt is tetra-n-
butylphosphonium chloride.
29

Description

11~)3665
Back~round of the Invention
The esters of thiocarbamic acids are useful for a
variety of purposes. Some are active herbicides, others are
effective for inhibiting the growth of micro-organisms such as
bacteria, and still others are active insecticides. The
S following is a group of processes representative of those known
in the art ~or the preparation of these compounds.
U.S. Patent No. 2,983,747 employs zinc chloride as a
catalyst in the direct reaction of carbamyl chlorides with
mercaptans to produce various thiocarbamic esters. Although the
reaction can be conducted without the use of a solvent, a solvent
inert to the catalyst, such as an organic solvent, m~st ~e used
if a solvent is employed.
U.S. Patent 2,913,327 teaches the preparation of the
sodium salt of a mercaptan followed by reaction with a carbamyl
chloride in the presence of a solvent. The use of the sodium
salt of the mercaptan causes problems of filtration and solids
handling. The use of a solvent reduces reactor capacity
throughout. In addition, solvent recovery can be a problem.
Furthermore, the hydrogen evolved during the preparation of the
sod~wm salt causes a disposal problem.
U.S. Patent 3,133,947 describes the preparation of
esters of thiocarbamic acids by a process comprising reacting a
secondary or primary amine with carbonyl sulfide in the presence
of a basic material which may be any amine, including a tertiary
amine, and thereafter reacting the intermediate with an organic
-2- ~

l~iO3665
sulfate, such as a dialkyl sulfate, or a diallyl sulfate. This
process is unfavorable because of the special gas handling
equipment required for the carbonyl sulfide addition. Further,
alkyl sulfate values are lost, thus adding to the expense of the
overall process.
U.S. Patent 3,8~6,524 teaches the preparation of
thiocarbamic acid este~s by reaction of a carbamyl chloride with
a mercaptan in the presence of an aqueous solution of a caustic
agent. This process requires considerable agitation in order to
form a high interfacial area between the two liquid phases~ as
well as a high caustic concentration in order to achieve the
desired conversion and product purity.
In view of the problems as enumerated hereinabove,
wh~ch are encountered in the prior art processes, it is the object
of this invention to provide a process for the preparation of
esters of thiocarbamic acids which provides high yields as well
as a savings in starting materials and operating expenses.
In another aspect, it is an object of this invention to
provide a novel use for a phase transfer catalyst, in enhancing
the reaction between a carbamyl chloride and a mercaptan in the
presence of an aqueous solution of a caustic agent to produce a
thiocarbamic acid ester.
Phase transfer catalysts are known for their ability to
promote reactions between reactants residing in separate but
contiguoUc liquid phases by transfering one reactant across the
interface. The use of phase transfer catalysts in alkyl halide

ilO3665
displacement reactions, dichlorocyclopropanation of alkenes,
oY~idation of alkenes, and other reactions is taught in C. M.
Starks~ J. Am. Chem. Soc. 93 ~1), 195-199 (1971). Other uses
are disclosed in W. P. Weber, G. W. Gokel, and I. K. Ugi,
An~ew. Chem. Internat. Edit. 11 (6), 530-531 (1972), H. E. Hennis,
L. E. Thompson, and J. P. Long, I & EC Prod. Res. and Dev. 7 (2),
96-101 (1968), and British Patent 1,227,144.
-4-

il~ 366~5
Summary and Brief Description of the Invention
This in~ention relates to a novel method of preparing
members of the class of compounds known as thiocarbamates. More
particularly, this invention relates to the method of preparing
esters of thiocarbamic acids by the reaction of an appropriate
carbamyl chloride and requisite mercaptan in the presence of
(i) an aqueous solution of a caustic agent, and (ii) a catalytic
amount of a phase transfer catalyst.
Generally, any mercaptan or carbamyl chloride can be us~d
in the instant process. The general reaction scheme can be
represented as follows:
_ OH- R ~ R
NCCl $ RS - ~ ~ NC SR + Cl
R / R ~
in which examples of mercaptans and carbamyl chlorides which can
be used ~re those in which
R represents:
alkyl, having 1 to 12 carbon atoms, in~lusîve;
haloalkyl, having 1 to 12 carbon atoms, inclusive, preferably
chloro- or bromo-~ubstituted alkyl;
alkylthioalkylene, having a total of from 2 to 10 carbon atoms,
înclusive;
alkoxyalkylene, having a total of from 2 to 10 carbon atoms,
inclusive;
cycloal~yl, having 3 to 7 carbon atoms, înclusive;
alkenyl, having at least 1 double bond and from 2 to 8 carbon
atoms, inclusive;

~;1)36~5
alkynyl, h~v ~g at least one triple bond and from 3 to 6 carbon
atoms, inclusive, for example: isobutynyl, 3-methyl-
butyn-(l)yl(3);
phenyl;
naphthyl;
benzyl;
c~-alkyl benzyl, in which the alkyl has 1 to 4 carbon atoms,
inclusive;
substituted phenyl wherein the substituents include alkoxy having
1 to 4 carbon atoms, inclusive, nitro, chloro, trifluoro,
methyl, for example: o-methoxy, m-butoxy, p-nitro,
3,4-dinitro, 2,4-dinitro;
substituted naphthyl, wherein said substituents include alkoxy,
nitro, chloro, bromo, trifluoromethyl;
halo~lkenyl, in which alkenyl has 2 to 6 carbon atoms, inclusive,
and halo is chloro, bromo, iodo, or fluoro, for
example: 2,3-dichlcroallyl, 3,4,4-trifluoro-3-butenyl,
2-bromoallyl, and the like;
cyclohexenyl;
substituted benzyl, wherein the substituents are, for example:
chlorine, bromine, fluorine, methyl-p-methyl, o-methyl,
2,4-dimethyl, 2,6-dimethyl, 2,4-dichloro, 3,4-dichloro,
ar,~r,ar-trichloro, 5-chloro-2-methoxy, nitro;
carboalkoxy~lkyl, having from 2 to 8 c~rbon atoms, inclusive;
phenyl thioethyl;
phenyl oxyethyl;
pyrimidyl;
pyridyl;
indazolyl;
^6-

~)3665
quinolyl;
isoquinolyl;
furyl; and
dibenzofuryl;
Rl and R2 independently represent:
alkyl, having from 1 to 12 carbon atoms, inclusive;
slkenyl, having at least 1 double bond and from 2 to 8 carbon
atoms, inclusive;
haloalkyl, having from 1 to 12 carbon atoms, inclusive, where
kalo is chloro, fluoro, or bromo;
cyano-substituted alkyl, having from 2 to 6 carbon atoms,
inclusive;
alkynyl, having at least one triple bond and from 3 to 6 carbon
atoms, inclusive, for example: propargyl, isobutynyl,
and the like;
cyclohexenyl;
haloalkenyl, having from 2 to 8 carbon atoms, inclus~ve, where
halo is chloro, fluoro, or bromo;
benzyl;
substituted-benzyl, in which the substituents are, for example:
chloro, lower alkoxy having 1 to 4 carbon atoms,
inclusive, cyano, nitro and trifluoromethyl;
hal.oalkoxy, having 1 to 8 carbon atoms, inclusive, where halo
is chloro, fluoro, or bromo;
alkoxy, having 1 to 8 carbon atoms, inclusive;
alkenyloxy, having at least 1 double bond and from 2 to 8 carbon
atoms, inclusive;
nitroalkoxy, having 1 to 6 carbon atoms, inclusive;

$~Q36~i5
phenyl;
substituted-phenyl, in which the substitutents are, for example:
chloro, bromo, nitro, cyano, alkoxy having 1 to 4
carbon atoms, inclusive, phenyl and the like;
phenoxy-substituted alkyl, in which alkyl has from 1 to 4 carbon
atoms, inclusive;
naphthyl;
furfuryl, tetra-hydrofurfuryl;
cycloalkyl, having from 3 to 7 carbon atoms, inclusive;
heterocyclic oxygen, nitrogen or sulfur-containing ring groups,
for example: pyridyl, ~hienyl, f~ryL, pyranyl,
pyrimidinyl, indolyl, quinolyl~ isothioazolyl, piperidyl,
piperazinyl, morpholinyl and the like;
alkyl-substituted pyridyl, where alkyl h~s from 1 to 4 carbon
atoms, inclusive; and
Rl and R2 taken together with the nitrogen to which
they are attached represent heterocyclic groups, e.g., pyrryl,
pyrrolidyl, pyrazolyl, pyrazolinyl, piperldinyl~ imidazolyl,
indolyl, ~ ~methylindolyl, aziridinyl, carbazolyl, morpholinyl,
3-azablcyclo-[3.2.2]nonanyl-3, polyalkylen~mine, having 3 to 6
carbon atoms, inclusive, alkyl-substituted piperidine, for
example, 5-ethyl^2-methyl piperidine.
The advantages of the present inven~ion over the
closest prior art~ U. S. Patent 3,836,524, are as follows:
1) a rnuch lower concentration of caustic solution
will produce the same conversion and purity,

~ ~ 36~65
2) a lower excess of mercaptan with respect to carbamyl
chloride will produce the same conversion,
3) less agitation is needed, and
4) reaction times are sharply reduced.
Detsiled Description of the Invention
As stated hereinabove, the process of the present
invention comprises reacting a carbamyl chloride with a mercaptan
in the presence of (i) an aqueous solution of a caustic agent,
and (ii) a catalytic amount of 8 phase transfer catalyst. The
components of the reaction mixture can be added in any order,
for example:
(a) a mixture of the mercaptan and the phase transfer
catalyst can be added to the caustic solution, and the resulting
mixture ~hen added to the carbamyl chloride;
(b) a mixture of the phase transfer catalyst, the
lS mercaptan, and the carbamyl chloride can be sdded to the caustic
solution; or
(c) the phase transfer catalyst can be added to the
carbamyl chloride which is then added to a mixture of the mercaptan
and the caustic solution.
The lat~er is the preferred mode of addition for carbsmyl
chlorides and mercaptans in general. Mode (b) is preferred when
the mercaptide salt is insoluble in the caustic solution. In
any case, the resulting reaction mixture forms two liquid
phases: an organic phase containing the carbamyl chloride, and
an aqueous phase containing the caustic and the mercaptan.

~3U665
The term "phase transfer catalyst" is used herein to
represent any catalyst which facilitates the transfer of a chemical
species from one liquid phase to another. Examples of such
catalysts are quaternary salts having the formula
(R3R4R5R6M) X
wherein R3, R4, R5, and R6 are hydrocarbon radicals selected
ir.dependently from the group consisting of alkyl, alkenyl, aryl,
alkaryl, aralkyl, and cycloalkyl radicals; M is a member selected
from the group consisting of nitrogen, phosphorus, arsenic,
antimony, and bismuth, preferably nitrogen or phosphorus; and X is
an anion which will dissociate from the cation in an aqueous
environment, preferably a halide ion or a hydroxyl ion, most
preferably chloride or bromide.
As used in the description of R3, R4, RS, and R6
above:
~he term "alkyl" refers to a monovalent straight or
branched chain saturated aliphatic hydrocarbon group of 1 to 25
carbon atoms, inclusive, e.~g., methyl, ethyl, propyl, i-propyl,
n-butyl, s-butyl, t-butyl, n-octyl, 2-methyloctyl, decyl,
6-methylundecyl, dodecyl, and the like;
the term "alkenyl" refers to a monovalent straight or
branched chain aliphatic hydrocarbon of ~ to 25 carbon atoms,
inclusive, and containing at leas~ one double bond, e.g., allyl,
butenyl, butadienyl~ and the like;
the tenm "aryl" refers to a monovalent monocyclic or
bicyclic aromatic hydrocarbcn group, i.e., phenyl and naphthyl;
-10-

llV366~
the term "alkaryl" refers to an aryl groups as defined
above, in which at least one hydrogen atom is substituted by an
alkyl group as defined above, e.g., tolyl, xylyl, mesityl,
ethylphenyl, and the like;
the term "aralkyl" refers to an alkyl group as defined
above, in which a hydrogen atom is substitutet by an aryl or
alkaryl group as defined above, e.g., benzyl, phenethyl, methyl-
benzyl, naphthylmethyl, and the like; and
the term "cycloalkyl" refers to a monovalent cyclical
sat~rated hydrocarbon group of 4 to 8 carbon atoms, inclusive,
i.e., cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and
cyclooctyl.
Mixtures of such quaternary salts may likewise be
utili~ed in the practice of the invention. Double or multi-
functional quaternary salts in which the general formula
(R3R4R5R6M)+ X ~s repeated a plurality of times with the same
or different substituent combinations, can also be utilized
effectively.
The most preferred phase transfer catalysts are tetra-
n-butylphosphoni~m chloride, hexadecyltributylphosphonium bromide,
benzyltriethylammonium chloride, benzyltriethylammonium bromide,
tricaprylylmethylammonium chloride, and dimethyldicocoammonium
chloride~ The latter two catalysts are manufactured by General
Mil~ Co., Chemical Division, Kankakee, Illinois, and are
Q
alternatively designated by the names "Aliquat 336" and llAliq~at
221'i, respectively.
c~

~036~s
The term "catalytic amour.t" is used herein to represent
any amount of phase transfer catalyst which will enhance the
progress of the reaction. The amount of catalyst normally will
range from about 0.2 to about 5.0 weight % of the reaction mixture,
preferably from about 0.5 to about 1.0 weight %.
The ratio of reactants employed in the instant process
can vary widely. Normally, the mole ratio of mercaptan (RSH) to
carbamyl chloride (R *2NCOCl) is at least about 1Ø The
preferred ratio of mercaptan to carbamyl chloride is at least
about 1.1.
The mole ratio of caustic agent to mercaptan is at least
about 0.5, however, the preferred ratio of caustic agent to
mercaptan is at least about 1Ø Thus, in the most preferred
form, this process is carried out with an excess of caustic agent.
The term "caustic agent" is used herein to mean any inorganic
material which will sufficiently produce hydroxyl ions in an
aqueous solution to function in this process. The nature of the
caustic agent must produce sufficient alkalinity in an aqueous
solution to inhibit or suppress the hydrolysis of the mercaptide
RS ion to the mercaptan according to the equation:
RS + H20 ~SH + OH
The caustic agents contemplated for use in this process include,
among others, sodium hydroxide, potassium hydroxide, barium
hydroxi~e, and the like, and m~xtures thereof. The caustic agent
is supplied to the reaction scheme as an aqueous solution which
can range from about 5% to about 50%, such that the solution is

1 ~0 36~5
liquid. For example, when using sodium hydroxide, the preferred
range of caustic solution is about 10% to about 30% by weight.
The conditions of the reaction can be varied rather
extensively without having an appreciable effect on the yield or
quality of the product. The temperature of the reaction can range
from about 10C to about 100C and preferably from about 20C to
about 80C. Within the temperature l~mit~ specified herein, it is
found that esters of thiocarbamic acids can be prepared and that
the undesirable by-product acids of the corresponding urea will be
minimized. The selected temperature also determines the rate of
the reaction; that is, the time required to economically and
feasibly arrive at the product with a negligible amount of carbamyl
chloride remaining. The reaction time, therefore, will depend
upon several interacting factors, such as temperature and degree
15- of agitation.
Although agitation is not essent~al to the efficient
progress of the reaction, there is still an advantage to be
gained in reaction time by the use of agitation to increase the
interfacial area between the two liquid phases. Agitation can be
~0 achieved, for example, by the use of stirrers, baffle plates
within the reaction vessel, turbulence columns and the like.
The present invention may be practiced in a batch or
batch-like fonm or in a continuous or continuous-like form. ~hen
the invention is practiced in a manner resembling a ba~ch process,
all the various species will be combined in steps detenmined by a
uitable t~me sequence into a single body o~ liquid. When a

~ 1~ 3~ 5
continuous or continuous-like form is used, the desired reaction
rate can be achieved by selecting a suitable type of agitation
and appropriate reaction conditions. The choice`between the
various types of process to be used will depend on the desired
manufacturing conditions. The reaction vessel or vessels will
preferably consis~ of non-corrosive materials, such as mild steel,
which will not interfere with the principal reaction.
Upon completion of the process reaction, the thiocarba-
mate ester product will rem-ain in the organic phase. Salt which
may have precipitated during the reaction can be dissolved readily
by the addition of water. The two liquid phases are subsequently
separated. The organic phase is dried and the thiocarbamate ester
is recovered therefrom. The product can be stripped of residual
water and volatile components by purging with argon or nitrogen
while heating. Further purification can be achieved by conventional
purification techniques.
Specific examples are set forth below showing the prepara-
tion of thiocarbamic acid esters by the process of the present
invention. These examples are included for illustrative purposes
only, and are not to be interpreted as imposing any limitations on
the scope of the invention herein described. Such limitations are
set forth in the appended claims.
EXAMPLES
General Procedure
The general procedure used in the following exper~ments
was as follows. An aqueous solution of sodium hydroxide was
placed in an agitation flask equipped with a stirrer. The
-14-

~36~;5
appropriate mercaptan was added to the aqueous solution. To this
- mixture was added the requisite carbamyl chloride with the phase
transfer catalyst dissolved therein, while maintaining the flask
and its contents at the indicated temperature At the end of the
experiment water was added when necessary to dissolve any precip-
itated salts, and the organic layer containing the thiocarbamic
acid ester was separated. The organic layer was either heated
under a vac~um or purged with nitrogen while heating to remove
residual water and mercaptan. The reactants, products, catalysts,
conditions and results are summarized and reported in the following
Tables I, II, and III. The results are area percent from gas
chromatography analysis of the material. In several instances, a
weight percent purity also was determined and found to agree within
experimental error to the gas chromatographic analysis.
-15-

il~3665
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1103665
Of particular interest in the data in Table III are
comparisons between Experiments 8 and 8a, between 9 and 9a, and
between 10 and lOa. Each pair demonstrates the progress of the
reaction both with and without a phase transfer catalyst. The
data show a striking ad~antage gained in each case in both
reaction t~me and product purity by the use of the catalyst.
Although a comparison between Experiments 16 and 9a shows no
advantage in the data presented to be gained by the use of
benzyltriethylammonium chloride, an increase in rate, not shown
in the table, did occur. The reaction did not proceed o
completion since the catalyst was not soluble in the carbamyl
chloride. A complete reaction will be achieved either when the
same catalyst is used with a carbamyl chloride in which ~t is
soluble, or when a different catalyst is used which is soluble
in the carbamyl chloride used in Experiment 16. The ad~antage
of a system where all components are soluble is thus apparent.
The ph~se transfer catalyst used may also act as an emulsifying
agent, and thus facilitate mixing.
Compound Activity Data
A3 ~tated hereinabove, the thiocarbamic acid esters
prepared by the proces~ of the invention are useful as herbicides,
gr~wth inhibitors, and insectic1des. Herbicide activlty of some
of the compounts made in the above examples by the process of the
invention was determined by the following screening procedures.
-~0-

i~O3u66 5
Pre-emer~ence Herbicide Screenin~ Test
Using an analytical bslance, 20 mg of the compound to
be tested is weighed out on ~ piece of glassine weighing paper.
The paper and compound ~re placed in 8 30 ml wide-mouth bottle
~nd 3 ml of acetone containing 1% Tween 20~ (~ polyoxyethylene
5~ sorbit~n monolsurate) is added to dissolve the compound. If
the msterifll is not soluble in ~cetone, another solvent ~uch as
water~ alcohol or dimethylformsmide (DMF) is used instead. When
DMF i8 u3ed, only 0.5 ml or less i8 used to dissolve the compound
and then Another solvent is used to make the volume up to 3 ml.
IOE The 3 ml of solution is spr~yed unifonmly on the 30il contained
in a ~mall fiber fl~t one day after planting weed seeds in the
flat of soil. A No. 152 DeVilbiss atomizer is used to apply the
Qpray using compressed air ~t a pressure of 5 lb/sq.in. The
rAte of ~pplication is 8 lb/acre and the spr~y volume is 143
1~ g~l/acre.
On the day preceding tre~tment, the fiber fl~t, which is
7 inches long, 5 inches wide and 2.75 inches deep , is filled to
a depth of 2 inches with loamy sand soil. Seeds of seven different
weed species are plsnted in individual rows using one species per
2~ row acro~ the width of the fl~t. The seeds are covered with
soil so that they ~re pl~nted at a depth of O.S inch. The seeds
used are h~iry crabgras~ (Di~itflria san~uinalis), yellow foxt~il
(Sethria ~lauca), redroot pigweed (Am~ranthus retroflexu~),
Indian mustard (Brassica ~uncea), curly dock (Rumex crispus),
Z~ w~tergrass (Echinochloa crusgalli), snd red oat (Avena sativs).
Ample ~eeds are planted to give sbout 20 to 50 seedlings per
row after emergence depending on the s~ze of the plants.
-21-

r~
1~ 6~5
Af~er trestment, the flats ~re placed in the greenhouse
at a temperature of 70 to 8SF snd watered by sprinkling. Two
weeks ~fter trestment the degree of injury or control is deter-
mined by comp~rison with untreated check pl~nts of the same age.
The in~ury rating from 0 to lOOqo is recorded for each s~ecies
- ~s percent control with 07O representing no in~ury and 1007o
representing complete kill.
Post-emer~ence Herbicide Screenin~ Test
Seeds of 8iX plant species, including halry crabgrass,
watergr~ss~ red oat, mustard, curly dock and Pinto beans
(Phaseolus vul~aris~ are planted in the Styrofoam flats as tes-
; cribed above for pre-emergence screening. The flats ~re placedin the greenhouse st 70 to 85F and wstered daily with a sprinkler.
About 10 to 14 days after planting when the primary leaves of
the bean p$ants are almost fully expanded and the first tri-
foli~te le~ve~ re ~ust atarting to form, the plsnts ~re sprayed.
The spray is prepared by weighiQg out 20 mg of the test compound,
dissolv~ng it in 5 ml of ~cetone cont~ining 1% Tween 2 ~ and then
adding 5 ml of water. The solution is ~r~yed on the foliage
using a No. 152 DeVilbiss Rtomizer at ~n sir pressure of 5 lb/
sq. ln. The ~pray concentration is 0.2 ~nd the rate is 8 lb/~cre.
The spray volume i9 476 gsl/~cre. In~ury r~tings sre recorded
14 days a~ter treatment. The rating ~ystem is the ~sme as des-
cribed ~bove in ~e-emergence test.
The resul~s of these tests ~re shown in Table IV.

~1~3~5
TABLE IV
Herbicide ActivitY
Product of Percent Control at 8 lb/A
Experiment
No. Pre-EmerRence Post-Emer~ence
,
1 90 . 8
2 59 5
3 95 7
4 74 17
62 13
: 11 53 45
*
Aver~ge for seven plant species in ~he pre-emergence test
and for ~ix plant specles in the post-emergence test.
~23~