Note: Descriptions are shown in the official language in which they were submitted.
1060()37
One of tlle problems encountered during the
preparation Or merca~tans by most Or the common commercial
methods is the formation ol by-produced sulfides. This
occurs both when H2S is added to unsaturated compounds and
~Ihen the hertofore employed alkali metal hydrosulfides are
reacted with chlorides or bromides. The reason for the
formation Or sulfi~es in the first process is because the
mercaptan adds to a double bond more rapidly than the
H2S. With respect to the hydrosulfide reaction, all alkali
metal hydrosulfides contain alkali metal sulfides. These
give rise to the organic sulfide by-product. Another method
which has been employed for the production of mercaptans is
shown in U.S. Patent No. 3,590,065. This involves the
reaction of an organic halide with thiourea in the
presence of ammonia. The products are the mercaptan and
guanidine hydrochloride which is voluminous in character
and imposes a serious disposal problem.
It is known from U.S. Patent No. 3,849,471 that
mercaptoalkyl silicon compounds can be prepared by reacting
chloroalkyl-substituted silicon compounds with H2S in the
presence of ethylene diamine. This patent shows column 9,
Example 13, runs 22 to 25 that amines such as tributyl amine,
pyridine and diethylene triamine do not cause the reaction to
go to any significant extent. It is, therefore, most
unexpected that ammonia and the amines of this inventlon
cause the reaction to proceed in excellent yields.
It is an ob~ect of this invention to provide a
novel method for preparing mercaptans which5 under the right
conditions, avoids the formation of any significant amount
of sulfide and which at the same time uses inexpensive reagents.
. ''
1060(~37
Thus, this invention represents an advance in the art of
preparing mercaptans which gives economic advantages over
prior processes.
This invention relates to a method of producing
mercaptans ~Jhich comprises reacting (A) a halide of the formula
RXa wlth a mixture of (B) ammonia or a hydrocarbyl amine
containing one ~J atom, no more than 6 carbon atoms and being
free of aliphatic unsaturation and having a Ka of less than
1 x 10 9 in aqueous solution, and H2S, in the mole ratio of
at least one mole of H2S and one mole of (B) per mole of
halogen in (A) at a temperature of from 0 to 175C. under
autogenous pressure whereby a compound of the formula R(SH)a
is formed, in which process R is selected from the group
consisting of aliphatic, cycloaliphatic or aralkyl hydrocarbon
radicals free of aliphatic unsaturation, such hydrocarbon
radicals substituted with alkoxy, keto, carboxyl, hydroxyl,
-CooR3 or -ooCR3 in which R3 is a monovalent hydrocarbon
radical free of aliphatic unsaturation, and silylated
hydrocarbon radicals of the formula (R~tO)yR~ ySiR4~ or
0 dR " 'dSiR4- in which R " is an alkyl or an alkoxyalkyl
radical of 1 to 6 carbon atoms, R " ' i5 a monovalent
hydrocarbon radical free of aliphatic unsaturation, a
haloaryl radical or RfCH2CH2- in which R~ is a perfluoroalkyl
radical, R4 is a divalent or trivalent aliphatic, cycloaliphatic
or aralkyl radical free of aliphatic unsaturation, y is l to 3, .
and d is 0 to 2, X is bromine or chlorine, and a is 1 to 3.
. It can be seen that the halide reactant (A) can
contain 1, 2 or 3 halogen atoms and that these can be chlorine
or bromine or a combination thereof. The halogen atom is
attached to an allphatic or cycloaliphatic carbon atom and R
--2-- .
.~,,j .
~)6S)037
is free of aliphatic unsaturation. R then, can be any alkyl
radical such as methyl, ethylj propyl, isopropyl, hexyl or
octadecyl, or any cycloaliphatic hydrocarbon radical such as
cyclopentyl, cyclobutyl, cyclohexyl or methylcyclohexyl~ or
any aralkyl hydrocarbon radical such as benzyl, beta-phenylethyl,
2-phenylpropyl, beta-xenylethyl, gamma-naphthylpropyl and the
like. Typical halides then are ethylc~loride, 1,3-propylene- r
dibromide-1,2,3-trichloropropane and 1-chloro-3-bromocyclo-
hexane.
In addition, the reactant (A) can be substituted
with one or more of the defined substituents so that (A) can
be a haloether such as chloromethylmethylether, chloroethyl-
ethylether, bis-chloromethylether, chlorobutylmethylether,
chloromethylphenylether or chloromethylbenzylether; or
halo~enated ketones such as bromomethylmethyl ketone,
chloro~ethylethyl ketone, chloromethylphenyl ketone,
chloroethylbenzyl ketone or bis-chloroethyl ketone;
halogenated carboxylic acids such as chloroacetic acid, -~
alpha-chloropropionic acid, beta-bromopropionic acid,
gamma-chlorobutyric acid or chlorocyclohexylcarboxylic acid.
It should be understood, of course, that the products formed
by the reaction of a halogenated acid produces the
corresponding ammonium or amine salt~ The free acid can
be obtained by reacting this salt with a strong acid such
as hydrochloric, nitric, etc. In addition, (A) can be a
halo alcohol such as beta-chloroethanol, beta-chloropropanol
or bromohexanol. (A) can be an ester of a halogenated ~-
carboxylic acid which ester contains the group -COOR3
in which R3 iS a mono~alent hydrocarbon radical such as
methyl, ethyl, isopropyl, butyl, phenyl, cyclohexyl or
, .
- .
.
10~60037
benzyl or (A) can be a carboxylic acid ester of a halo
alcohol which ester contains the group -ooCR3 in which R3
is as above described.
In addition, (A) can be a silane of the formula
(Rl'O)yR'l' ySiR4~ or a siloxane of the formula 03-dR " 'dSiR4-
in which silanes and siloxanes R'' is any alk~l radical suchas methyl, ethyl, isopropyl, butyl or hexyl or any alkoxyalkyl
radicals such as -OCH2CH20CH3 or O(CH2CH20)2C2H5 and R " ' is
any monovalent hydrocarbon radical free of aliphatic
unsaturation such as methyl, ethyl, isopropyl, butyl, phenyl~
xenyl, naphthyl, benzyl, beta-phenylethyl, 2~phenylpropyl or
cyclohexyl; any haloaryl radical such as chlorophenyl,
dichlorophenyl, chloroxenyl or chloroanthracyl or
~luorinated hydrocarbon radicals of the formula RfCHzCH2-
in which Rf is any perfluoroalkyl radical such as
perfluoromethyl, perfluoroethyl, perfluorobutyl, perfluoro-
isobutyl or perfluorooctyl. The divalent radical R4 between
the halogen and the silicon can be any divalent aliphatic
hydrocarbon radical such as methylene3 dimethylene,
trimethylene, isobutylene or ocatdecamethylene or any cyclo-
alkyiene radical such as cyclohexylene, methylcyclohexylene,
cyclopentylene or cyclobutylene or any araIkylene radical
ln whlch the silicon is attached to the aromatic ring, such
Me
as benzyleneg -C6H~CH2CHz-~ -C~H4CHCH2-, o~ -CH2CH2C6H4CH2-.
R~ can also be trivalent or tetravalent radicals of the
~bove type ln which case a has a value of 2 or 3 respectively.
The slloxanes employed as reactants can be
homopolymers or copolymers and they can have either 1, 2 or
3 organic radicals substituted on the silicon atom. Also
_4_
~060~3'7
these slloxanes can contaln ;ome sllicon-bonded hydroxyl
groups and some copolymerized organosiloxane un~ts, which
are free of reactive halogenated units of the formula
R'~'zSiO4-z in which R " ' is aS above defined and z i9 0 to
3, such as, for example, dimethylsiloxane units, phenylmethyl-
- siloxane units, trimethylsiloxane units, trifluoropropyl-
methylsiloxane units, diphenylsiloxane units, monophenyl-
siloxane units, monomethylsiloxane units or sio2 units. Of
course, in these copolymers there should be at least one
siloxane unit having the defined ~R9~a substituents. SucA
copolymers are considered within the process Or this invention.
Reactant (B) employed in this invention can be
ammonia or any hydrocarbon amine containing one ~ atom and no
more than 6 carbon atoms which is free of aliphatic unsaturation
and has a Ka of less than 1 x 10 9. This means that the amines
are those in which the nitrogen is attached to aliphatic or
cycloaliphatic carbon atoms, Specific examples of such amines
are primary amines such as methyl amine, butyl amine,
isopropyl amine, cyclohexyl amine and cyclopentyl amine;
secondary amines such as dimethyl amine, dipropyl amine and
methylbutyl amine and tertiary amines such as trimethyl amine,
triethyl amine or ethyldimethyl amine. The total number
of carbcn atoms in the amine should be no more than 6.
The mole ratio of (B) to H2S is not critical since
either can be in large excess over the other. However, for
best results there ~hould be at least one mole of H2S and one
mole of (B) per mole of halogen in (A).
The reaction of this invention is best carried out
at a temperature from 0 to 175C. under autogenous pressure.
The optimum temperature to be employed with any particular
type of reagent varies, but in general~ the higher the
_
~-r ~ r~
~16~037
temperature, the less sulfide produced. The pressure, of
course, will vary with the temperature and the volati;ity of
the reactants. If desired, external pressure can be applied
to the system, but this is unnecessary because the autogenous
pressure is sufficient for excellent yields.
In many cases, it is advantageous to employ a polar
solvent in the reaction. ~xamples of operative polar solvents
are water, alcohols such as methanol, ethanol, isopropanol or
butanol; ethers such as dioxane, the dimethyl ether of
ethylene glycol or the monomethyl ether of ethylene glycol;
nitriles such as acetonitrile or propionitrile;
N,N-disubstituted amides such as dimethyl acetamide or
diethyl formamide and sulfur compounds such as dimethyl
sulfoxide. Obviously, the polar solvent should be non-acidic.
The following examples are illustrative only
and should not be construed as limiting the invention which
is properly delineated ln the appended claims. In the examples,
the following abbreviations are used: Me for methyl, Et for
ethyl, Pr for propyl and Ph for phenyl.
Example_l
Trimethyl amine (37 g., o.637 moles), hydrogen
sulfide (14.1 g., 0.415 moles) and (MeO)3Si(CH2)3Cl
(72 g., o.36 moles) were heated at 100C. in a 300 ml. stainless
steel autoclave. After 17 hours, a sample was withdrawn
and analyzed by ~lc. Chloropropyltrlmethoxysilane was not
detected by glc. The ma~or product was (MeO)3Si(CH2)3SH
(97 percent glc area) with small amounts of [(MeO)3Si(CHz)3]2S2
and [(MeO)~Si(CHz)3]2S.
.
--6--
~0~;0037
Exa~ple 2
A solution o~ equal ~olumes of triethyl amine and
methanol were saturated wlth hydrogen sulfide at room
temperature and atmospheric pressure. The H2S was present
in excess of 1 mole H2S per mole of amine. 3.49 g. of
n-hexyl chloride was added to 15 ml. of the above solution
and the mixture was heated in a sealed container at 75C.
After 6 hours, the product was 99.1 percent n-hexyl mercaptan
and 0.9 percent n-hexyl sulfide.
Example 3
78.4 g. of ammonia and 171 g. of hydrogen sulfide
were added to a three liter stainless steel autoclave. 100 ml.
of methanol were pumped into the vessel followed by 819 g. of
n-dodecyl chloride. This was followed by 20 ml. of methanol
to flush out the pump. The sealed container was heated at
125C. and after 22 hours gas liquid chromotography analysis
showed that the product was 98.7 percent n-dodecyl mercaptan
and 0.~ percent unreacted dodecyl chloride.
Example 4
3.3 g. of am~onia was added to 31.7 ml. of methanol
and then the solution was saturated with hydrogen sulfide.
While continuing the hydrogen sulfide addition, 19 ml. of
benzyl chloride was added and the mixture maintained at 0C.
After one hour, gas liquid chromotography indicated that the
product was 92 percent benzyl mercaptan and 8 percent benzyl
sulfide~
Example 5
A mixture of a saturated hydrogen sulfide solution
of 12.6 g. of benzyl chloride, 8.4~g. of n butyl amine, and
20 ml. of isopropanol was reacted at room temperature. After
.
.. , . , . ' . ~ '
~(~6003~7
15 to 30 n-inute~, ~as liquid chromotography analysis showed
that tlle reaction was 90 p~rcent complete ~nd the distribution
of materials was 10 percent unreacted benzyl chloride, 82
percent benzyl mercaptan and 6 percent ben~yl sulfide.
Example 6
A solution of 10.9 g. of 1,2-dibromoethane,
13.5 g. of dipropyl amine and 10 ml. of methanol was saturated
with H2S and reacted at room temperature. Analysis of the
product by gas liquid chromotography showed it to be
1,2-ethane dithiol. No by-products were found.
Example 7
98 g. of ammonia, 211 g. of hydrogen sulfide and
990 g. of 3-chloropropyltrimethoxysilane were heated at
100C. in a closed container. After 5.7 hours, the reaction
was 81 percent complete and the product was 3-mercaptopropyl-
trlmethoxysilane.Example 8
A mixture of 95.9 g. of ammonia, 192.2 g. of
hydrogen sulfide, 970 g. of 3-chloropropyltrimethoxysilane
and 150 ml. of methanol were heated in a closed container
at 100C. for 18.5 hours. The initial pressure was 195 p.s.i.g.
(15.7 kg/cm2). After 18.5 hours, the pressure was 85 p.s.i.g.
(5.95 kg/cm2). The mixture was cooled and filtered free of
ammonium chloride. The ammonium chloride was washed twice
with 200 ml. portions of hexane. The original filtrate and
the hexane were combined and distilled. The product was
shown by gas liquid chromotography analysis to be 96.2
percent 3-mercaptopropyltrimethoxysilane, 3.2 percent
unreacted chloropropyltrimethoxysilane and 0.5 percent of an
unidentified impurity originally present in the chloropropyl
trlmethoxysilane. In other words, no sulfide was detected.
1~60037
Example 9
In an evacuated autoclave was charged 99 g. of
ammonia and 198 g. of hydrogen sulfide and the autoclave was
heated to 100C. 924 g. of 3-chloropropylmethyldimethoxy
silane and 100 ml. of methanol were then pumped into the
autoclave and heating was continued for 26.75 hours. After
cooling, the autoclave was emptied and the contents filtered
free of ammonium chlor~de. Gas liquid chromotography analysis
Or the product indicated a yield of 97 percent with a 94.2
percent conversion of the chloride to the mercaptan.
Example 10
682.5 g. of a siloxane of the unit formula
Cl(CH2)3SiMeO containing 1.41 percent by weight silicon-bonded
hydroxyl groups, 100 ml. of methanol, 97.5 g. of ammonia and
195.5 g. of hydrogen sulfide were mixed and heated at 125C.
for 24 hours. The initial pressure in the autoc}ave at
125~C. was about 500 p.s.i.g. (35.15 kg/cm2). After 24 hours,
the pressure was 195 p.s.i.g. (13.6 kg/cm2)r After 24 hours
at 125C., the product was cooled and diluted with ether and
filtered free of ammonium chloride. The product was
devolatilized at 2 mm. pressure at 60C. for 4 hours~ The
resulting product was 3-mercaptopropylmethylpolysiloxane
having the following properties: n25 1.5038, d-~ 1.115,
Rd 0.2655, Cal. Rd 0.2666. The yield of product was 95 percent.
Example 11
Equivalent results are obtained when cyclohexyl
amine is substituted for the triethyl amine of Example 2.
.
_ g _
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1060037
Example 12
Merca~tans are obtained when the following halides
are reacted with a mixture of ammonia and H2S ln the mole
ratio of 1:1 at 100C. under autogenous pressure.
Example 13
The experiment of Example 9 was repeated with
NH3 (100 g., 5.88 m~), H2S (127.5 g., 3.75 m.) and methanol
(100 ml.) at 100C. (MeO)2MeSi(CH2)3Cl ~593 g., 3.25 m.) ~Jas
pumped into the autoclave followed by 100 ml. of methanol.
Periodic analyses indicated:
Time %Initial
Hours(MeO)2MeSi(CH2)3Cl (MeO)2MeSi(CH2)3SH
0.5 13.1 85
1.5 5.8 92.1
2.5 2.6 94-7
This reaction was much faster than that of' Example 9.
.
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