Note: Descriptions are shown in the official language in which they were submitted.
~3~ 75
DESCRIPTION
PROD~CING ALKOXYSILANES AND
ALKOXY-OXIMINOSILANES
BACKGROUND OF THE INVENTION
-
The present invention rel,ates to producing alkoxy-
silanes and alkoxy-oximinosilanes which are useful as
initiators or room temperature vulcanizing agents in
silicone rubber compounds.
Prior art processes for the production of alkoxy~
silanes have involved the reaction of silicon chlorides
such as methyltrichlorosilane (MTCS) with alcohols, with
strong bases such as pyridine or sodium rnetal used to
neutralize the byproduct HCl and drive the reaction to
completion. Similar processes have been disclosed for
producing oximinosilanes, with an oxime substituted for
the alcohol.
In Russian Author's Certificate 547,245 of G. V.
Ryasin et al (published May'22, 1981), a process is
described in which an oxirne acts as both reactant and
acid acceptor, such that six moles of methyl ethyl
ketoxime (MEKO) and one mole of MTCS produce one mole of
methyl tris(methyl ethyl Isetoximo) silane and three
moles of MEKO hydrochloride.
Oximinosilanes are superior in performance to
alkoxysilanes as initiators for silicone rubbers because
of more rapid hydrolysis. Alkoxysilanes have the advan-
~;~36'~7~
--2--
tage of cheaper raw materials cost. The advantages of
both materials might be obtained by using some of each
in a molding composition. A more desirable alternative
would be to combine both functionalities on the same
molecule. See Ger Offen 2,055,712 (1971) (Chem Abstr
75:89238c); 2,065,407 ~1973) (Chem Abstr 80:4671u); and
Japan 74:39,967 (1974) (Chem Abstr 83:179292k).
BRIEF DESCRIPrION OF THE INVENTION
It has been discovered that oximes are good
acid acceptors for the reaction between alcohols and a
silicon halide, allowing the alkoxysilane to be formed
to the virtual exclusion of oximinosilane when the
alcohol is present in sufficient amounts. It has also
been discovered that, with less alcohol present than
required to react all halogens, initiator products hav-
ing a mixture of alkoxy and oximino groups are forTed.
Both reactions produce byproduct oxime hydrohalide
which is readily separable fro~n the organosilane prod-
uct, which organosilane product can be recovered and
purified by treatment with dry base.
Accordingly, the present invention includes a
process for the production of an alkoxysilane which com-
prises:
(a) reacting a silicon halide of the formula
R SiX, wherein n is an integer between 1 and 4,
4-n n
inclusive, and R is alkyl of 1-6 carbons, alkenyl of 2-6
carbons, cycloalkyl of 4-8 carbons, aryl, alkyl-substi-
tuted aryl, aralkyl or halosubstituted forms of any of
these with an alcohol of the formula R'OH, with R' being
alkyl of 1-24 carbons or aralkyl, in the presence of an
oxime compound of the formula R"R"'C=NOH, with R" and
R"' each being hydrogen or alkyl of 1-6 carbons or form-
ing a halosubstituted, alkylsubstituted or unsubstituted
cycloalkyl ring of 4-~ carbons and X is Cl, Br or I;
the molar ratio of alcohol to silicon halide
being at least n:l and the molar ratio of oxime to sili-
con halide being at least n:1; and
(b) recovering the alkoxysilane of the formula
~3~
--3--
R~ nSi(OR')n as major product and the hydrohalide of
said oxime as byproduct.
In additionS the pr~sent inventi~n includes in
this divisional specification a process for the production
of alkoxyoximinosilane~ which comprises:
(a) reacting a silicon halide of the formula
R4 nSiXn where R is alkyl of 1-6 carbons, alkenyl of
2-6 carbons, cycloalkyl of 4-8 carbons, aryl, alkyl-sub-
stituted aryl, aralkyl or halosubstituted forms of any
of these and n is an integer of 2-4 with an alcohol of
the formula R'OH, where R' is alkyl of 1-24 carbons or
aralkyl, and an oxime of the formula RnRn'C=NOH, with R"
and R"' each being hydrogen or alkyl of 1-6 carbons or
forming an unsubstituted, halosubstituted or al~yl-sub-
stituted cycloalkyl ring of 4-8 carbons and X is Cl, ~r
or I;
the molar ratio of alcohol to silicon halide
being m:l, wherein ~ is at least about 0.1 n and less
than nt and the molar ratio of oxime to silicon halide
being at least ~2n-m):l; and
- (b) recovering a product comprising at least
one alkoxyoximinosilane of the formula R4 nSi(OR')p
~ON=CR"R"')n p where p is an integer of 1-3, but is at
least one less than n, and the hydrohalide o said
oxime as byproduct.
DETAI LED DESCRIPI ION OF THE II~VENTION
.
The reactants in th~ present invention are
the halosilane, the oxime compound and the alcohol.
Suitable halosilanes (silicon halide such as silicon
chlorides) may be represented by the formula R4 nSiXr~.
In this formula R may be alkyl of 1-6 carbons such as
methyl, ethyl, propyl, isopropyl, butyl, pentyl, or
hexyls may be alkenyl of 2-6 carbons such as vinyl,
2-propenyl, 3-butenyl or 2-pentenyl; may be aryl such as
phenyl; may be cycloaLkyl suc~ as cyclobutyl, cyclo-
pentyl, cyclohexyl or cyclooctyl; may be alkyl-substi-
tuted aryl such as p-~ethylphenyl, p-ethylphenyl or
p-tertbutylphenyl; may be aralkyl such as ben3yl, or may
~3~
--4--
be halosubstituted forms of any of these such as
3-chlorocyclohexyl, chloromethyl, p-chlorophenyl or
p-bromophenyl. Furthermore, different R's on the same
molecule may differ, as in methyl ethyl dichlorosilane.
Preferred substituents R are methyl, ethyl, vinyl and
phenyl; with methyl and vinyl being most preferred. In
the above formula X may be Cl, Br or I, and is prefer-
ably Cl. Also in the ~bove ~ormula n may be 1, 2, 3 or
4, but is preferably 3 such that there is one R and
three X`s.
Representative silicon halides which may be
reacted with oxime compounds in the present process of
producing alkoxysilanes include methyl trichlorosilane,
phenyl trichlorosilane, vinyl trichlorosilane, ~imethyl
dichlorosilane, trimethyl chlorosilane, methyl ethyl
dichlorosilane, 2-chloroethyl trichlorosilane, silicon
tetrachloride, diethyl dichlorosilane, dimethyl dibromo-
silane, triethyl chlorosilane, benzyl trichlorosilane,
allyl trichlorosilane, trimethyl bromosilane, triphenyl
silyl chloride and trimethyl silyl iodide. All of the
above except the three trimethylhalosilanes and tri-
phenyl silyl chloride are also suitable for forming
oximinoalkoxysilanes. Preferred are silicon halides
wherein n is 3 and wherein R is alkyl (e.g. methyl and
ethyl) or alkenyl (e.g. vinyl) or phenyl.
The oxime used in the present process may be
any compound of the formula R"R"'C-~OH. In this formula
R" and R"' may each be ~ or alkyl of 1-6 carbons, aryl,
cycloalkyl, aralkyl, or any of these substituted by
halo; or R~ and Rn' may together be (CH2)m wherein m is
an integer from 3 to 7; or R" and R"' may together be
such a group substituted by alkyl or halogen. If R" or
Rn' or the two together are substituted by halogen, ~hen
the molecule should be one in which ~he halogen is not
reactive (e.g. ~logen on a tertiary carbon). Thus
suitable oximes include formaldehyde oxime, 4-methyl-
cyclohexanone oxime, 4-c~lorocyclohexanone oxime,
acetophenone oxime, benzophenone oxime, benzyl ethyl
~ ~31~ 7.1~
--5--
ketone oxime, cyclohexyl meth~l ketone oxi~e and
benzaldehyde oxime. Preferred oxime c~mpounds include
acetaldehyde oxime, acetone oxime, methyl ethyl ketone
oxime, diethyl ketone oxime and cyclohexanone oxime;
with methyl ethyl ketone oxime and acetone oxime being
more preferred. Methyl ethyl ketone oxime i5 most
preferred because of its use in many oximinosilane
compo~nds used as room temperature vulcanizing agents
for silicone polymers.
The alcohol R'OH used in the present invention
may be primary, secondary or tertiary, may otherwise be
branched or substituted and may be aralkyl. Examples
include methanol, ethanol, n-propanol, isopropanol,
isobutanol, t-butanol, isoamyl alcohol, hexanol, benzyl
alcohol, decanol, hexadecanol, stearyl alcohol, lauryl
alcohol and tetracosanol. Preferred alcohols are those
of 1-~ carbons.
In the practice of the present invention to
form alkoxysilanes, the mole ratio of oxime compound to
silicon halide is at least n:l and is preferably between
n:l and about 1.2 n:l. In cases wherein n is 3, this
translates into a mole ratio between 3:1 and about 3.6:1.
In the practice of the present invention to
form alkoxysilanes, the mole ratio of alcohol to silicon
halide is at least n:l and is preferably between n:l
and about 2n:1. Excesses of alcohol above the stoichi-
ometric ratio (n:1) are not deleterious, and may in fact
promote the desired alcohol reaction and suppress the
undesired oxime reaction. Since the excess alcohol
must ~e recycled to avoid being wasted, however, large
excesses are not preferred~
When the oxime is in the preferred range of
n:l to about 1.2n:1l excesses of alcohol need not be
large; and high yields of the desired product are ob-
35 tained a~ 1.2n:1 or ~.2n:1 alcohol:silicon halide,
with little increase in yields with still ~.ore alcohol.
In the practice of the present invention to
produce oximinoalkoxysilane, the alcohol:silicon halide
~ 3 ~ 7~3
ratio (m) should be less than n:l (to avoid prod~cing
mainly alkoxysilane). Thus if n is 3, m should be less
than 3, with a preferred overall ratio being between 0.5
and 2.5. Thus, if the desired primary product is
oximinodialkoxysilane, a value of m of about 2 is most
preferred. If the desired primary product is dioximino-
monoalkoxysilane, a value of m of about 1 is preferred.
Ratios between 1 and 2 will produce these two as primary
products. Ratios below 1 will produce dioximinomono-
alkoxysilane and trioximinosilane as primary products;ratio above 2 will produce oximinodialkoxysilane and
trialkoxysilanes as primary products. Similar preferred
ratios are m as 0.5-1.5 when n is 2 and m as 0.5-3.5
when n is 4. Sufficient oxime should be present to
co~plete the reactant stoichmetrics and HX neutraliza--
tion, i.e. at lea~t (2n-m):l.
Either the reaction may be done with neat
reactants or in the presence of a solvent. It has been
found that an inert hydrocarbon solvent such as hexane,
petroleum ether, toluene, or other similar low-boiling
materials may be advantageously used in order to lower
the viscosity of the reaction mixture and to lower both
the viscosity and the density of the product organo-
silane-containing phase so as to facilitate the separa-
tion of the organosilane products Erom the oxime hydro-
halide, which may be either a solid or a heaYier liquid.
Excess alcohol may, in some cases, also serve these
functions, pLovide~ that the alcohol does not hinder
phase separation. Under such circumstances, the pro-
portion of solvent to various reactants is not critical,with greater amounts of solvent acting to increase the
ease of separation, but requiring additional evaporation
or distillation to remove the solvent from the product
after separation of the product from oxime hydrohalide
by-product. For any particular system, the amount of
solvent preferably used can be easily determined; and in
the syste~ of meth~ltrlch~orosi~a~e reacted with alipha-
tic alcohols of 1-~ carbons and methyl ethyl ketone
~L~3~
oxime, a suitable ratio of solvent to methyltrichloro-
silane is between about 1:1 and 2:1 by weight.
The temperature at which the reaction occurs
is not critical, with the reaction occurring reasonably
S rapidly at room temperature or below, and with increas-
ing speed but with some increase in formcltion of color
bodies as the temperature increases. While a tempera-
ture range from about 0C to about 100C is generally
suitable, it is preferred, at least in the case of the
reaction between methyltrichlorosilane, aliphatic
alcohols of l-6 carbons and methyl ethyl ketone oxime,
to operate between abo~t 20C and about 70C. Because
th~ reaction is exothermic, a temperature at the higher
end of this range can normally be achieved by ihtroduc-
ing the reactants at room termperature and, withoutextensive heat exchange, allowing the reaction mixture
to heat up to a temperature of 30 to 60C. The time of
the reaction is also not critical since the reaction is
virtually instantaneous with reaction times (in the case
of batch processes) and residence times (in the case of
continuous processes) generally being in the range of 5
minutes to 5 hours, and especially 30 minutes to 2
hours. It will be appreciated that a suitable reaction
time can be determined by routine experimentation for
any particular set of reac~ants, solvent, temperature
and other operating conditions.
Once the reaction is completed, the product,
the by-product oxime hydrohalide, the solvent and any
unreacted oxime compound will generally separate into
two phases which are either two liquid phases or a
liquid phase and a solid phase at room temperature or
above. The first or organic phase (which is usually
the top phase) will contain essentially all the solvent,
essentially all of the product organosilane, most of
the unreacted oxime compound, most of the unreacted
alcohol and only minor amounts of the by-prod~ct oxime
hydrohalide. The second phase, which may be either a
liquid (generally the bottom phase) or a solid, will
7~
contain the by-product oxime hydrchalide, with small or
trace amounts of solvent, product oximinosilane,
unreacted alcohol and unreacted oxime compound. Unre-
acted alcohol will normally only be present when the
alcohol:silicon halide ratio was n:l or above, since
lesser amounts of alcohol would have been consumed in
the reaction. The phases may be separated by any con-
ventional technique, such as by decantation, filtration,
centrifugation or other conventional techniques for
separating solids from liquids or for separating two
liquids of different densities. In general, relatively
little time is required for the two phases to separate
in essentially clean fashion.
Once the phases are separated, the product is
recovered from the organic phase. One suitable method
of purifying the product, especially of any by-product
oxime hydrohalide, is to add to this organic phase a dry
basic compound, which is pre~erably ammonia gas, ~o as
to neutralize any oxime hydrohalide and generate
inorganic halides (e.g. ammonium chloride) which forms
an insoluble precipitate and free oxime compound. The
solid inorganic halide is then removed (e.g. by filtra-
tion or centrifugation), while the solvent, any unre-
acted alcohol, any unreacted oxime compound and any
oxime compound generated by the dry base are removed
from the organic phase by flash evaporation, distilla-
tion or other similar technique which takes advantage of
the relatively low boiling point of both the solvent and
the oxime compound (and the alcohol) relative to the
product organosilane. It is preferred that this evapo-
ration be conducted at subatmospheric pressures, e.g.
below 10 kPa, so as to minimize the temperature to which
the product organosilane is exposed. Thereafter, after
an optional filtration to remove any solids which may
have formed or accumulated during the evaporation step,
the product is ready for use. It will be appreciated
that, depending upon what R, R', R", R"', m and n are,
the products can be useful in a variety of applications,
9L~3~
and especially as room temperature vulcanizing or curing
agents for silicones. It is not required to distill the
product organosilanes as an overhead from any feed, but
rather through the combination of filtration and
evaporation of solvent, alcohol and oxime compound, a
relatively pure alkoxysilane or oximinoalkoxysilane (or
mixtures therebetween) may be produced.
In the separation of the reaction mixture, a second
phase is formed containing principally oxime hydrohalide
by-product. It is highly desirable to recover this
material in useful form either for recycle to the
reaction or otherwise. This material, after whatever
purification may be required, may be used for the
production of hydroxylamine salts. If, however, it is
desired to regenerate oxime compound from this oxime
hydrohalide, the preferred method is to mix this second
phase with a base, so as to generate a salt (preferably
an inorganic salt) and a free oxime compound. One
contemplated method for conducting this neutralization
is to add a dry base, and especially ammonia gas, to the
second phase until a moderate pH, (e.g. pH 7) is
achieved. Under these conditions large amounts of
ammonium chloride or other ammonium halide will form as
a precipitate in the oxime compound. By filtration or
otherwise, the ammonium salt may be removed; and a dry
oxime compound is then left, which may be recycled to
the main reaction with halosilane. It is desirable in
conducting such a neutralization with ammonia to
thoroughly agitate the slurry as it forms so as to
neutralize as much of the oxime hydrohalide as
possible. It will be appreciated, however, that any
oxime hydrohalide remaining in the oxime compound would
be recycled and be relatively inert in the reaction
mixture. Any alcohol present in this second phase would
also be recycled.
An alternate method of neutralizing the oxime
7~
--10--
hydrohalide i5 to add an aqueous base solution such as
aqueous ammonium hydroxide, aqueous sodium hydroxide,
aq~eous potassium hydroxide or the like so as to form an
aqueous salt solution, which phase separates from an
oxime compound. It is desirable in such a neutraliza-
tion process to either use aqueous base of proper con-
centration, or to have a separate feed of water in
proper ratio, to enable the mixture after neutralization
to separate and form a saturated salt so:Lution at the
temperature i~volved te.g. 25 percent sodium chloride at
room temperature~. The second layer would contain the
oxime compound (e.g. methyl ethyl ketone oxime); and the
solubility of the oxime compoun~ in the saturated
aqueous phase would then be minimized.
While neutralizàtion with aqueous base is a
generally easier procedure to follow, because of the
ease of mixing, lower viscosity, and absence of solids,
it has the disadvantage that it produces an oxime
compound containing some dissolved water. Depending
upon the use to which the oxime compound is to be
put, the water may be removed by passage through a
drying agent, distillation, azeotropic distillation
or other techniques. If the intention is to recycle the
oxime compound to the reaction with halosilane, it is
desirable to remove the water from the oxime compound
first, preferably down to levels of less than 1000 ppm.
Figure 1 illustrate~s a preferred embodiment
of the process of the invention wherein reactor 10 is
equipped with agitation and covered with an inert at-
mosphere (e.g. nitrogen) to assure reasonably anhydrousconditions. A solvent such as petroleum ether or hexane
is fed in stream 11 to reactor 10. An oxime such as
methyl ethyl ketone oxime (MEKO) and an alcohol such as
isopropanol are fed in stream 12 to reactor 10. A
halosilane (HS) such as methyltrichlorosilane (MTCS) is
fed in stream 13 to reactor 10. All three streams
should be essentially water-free (e.g. less than 1000
ppm water). The ratios of the three reactants may be,
7~;
for example, those set forth in cases l-ll below.
Silicon
Case Chloride n Alcohol:HS Oxime:HS
MTCS 3 3 3
2 MTCS . 3 4 3
3 MTCS 3 5 4
4 MTCS 3 2 4. 5
MTC S 3 1 5
6 DM DC S 2 2 2
7 DMDCS 2 1 3
8 DM DC S 2 1 4
9 STC 4 4
STC 4 3 5
11 TMCS 1 1 . 1
The above cases, in which MTCS is methyl-
trichlorosilane (i.e. n=3), DMDCS (i.e. n=2), STC is
silicon tetrachloride (i.e. n=4~ and TMCS is trimethyl-
chlorosilane ~i.e. n-l) illustrate various stoichio-
metri~s conte~plated.
The major product is alkoxysilane in cases
1-3, 6, 9 and 11 where the molar ratio of alcohol to
halosilane is at least l. Thus, cases 1-3 are illus-
trated by the following reaction:
CH3SiC13 + 3R'OH + 3(CH3) (C2H5)c=NO
CH3Si(OR' )3 + 3(CH3) (C2H5)C=NOH-HCl
The major product is alkoxyoximinosilane where that
ratio is less than l. Thus, case 4 is illustrated by
the following reaction (which will occur in competition
with reactions leading to products with more or less
alkoxy groups in the product):
CH3SiC13 ~ 2R'OH + 4~CH3) (C2H5)C=NOH
3Si (OR ) 21 ( CH3) (C2H5)C=NO] +
3 ~ CH3 ) (C2H5)C=NOH- H~l
Cases 2 and 3 illustrate the fact that larger
amounts of alcohol may be present (in which case they
will be recycled in the system of the Figure in stream
25). it is not preferred to use excess oxime without
excess alcohol (i.e. 1:3:4 for MTCS) since the propor-
. .
~,
`' ,
~3~7~
-12-
tion of alkoxyoximnosilanes in what is intended to be
alkoxysilane will increase. If it is desired to produce
the mixed product, then it is preferred to cut down in
the alcohol as in cases 4 and 5. Cases 6-8 indicate
that, when n=2, a 2:1 (or higher) alcohol:silicon halide
ratio is used to produce alkoxysilane, but a lower ratio
(e.g. 1:1) is used to produce alkoxyoximLnosilane.
Cases 9-10 illustrate producing the ~wo produc~s when
n=4. In n=l (case 11) only one product can be pro-
duced.
Reactor 10 may be operated in batch, semi-
continuous or continuous fashion with a residence time
of about 0.5-2 hours. In batch operation an initially
empty reactor 10 is charged with all three feeds and
the reaction mixture is agitated for the desired period.
Because of the reaction heat generated~ some cooling
may be applied by indirect cooling of the vessel or
bleeding off solvent vapor, so as to limit the tempera-
ture to about 30 - 60 C at maximum. After the reaction
period, reaction mixture is removed from reactor 10 in
stream 14 to separation vessel 15.
In continuous operation, as reaction mixture
is removed through stream 14, additional solvent, MEKO,
alcohol, and MCS are added in approximately the same
proportions as the initial charge, with the feed rates
of streams 11, 12, and 13 matching the withdrawal rate
in stream 14 ~which may be an overflow) and with an
average residence time at the desired 1-3 hour level.
- Various combinations of batch and continu-
ous operation will be apparent frcm the above to oneskilled in the art, and the present invention is not
limited to any particular form.
In separation vessel 15, a phase 16 consist-
ing essentially of product organosilanes [e.g. methyl
tris(isopropoxy)silane or mixtures including methyl
diisopropoxy ~methyl ethyl ketoximo) silane] and solvent
wil1 separate quickly and cleanly from a phase 17
consisting essentially of oxime hydrohalide ~e.g~
~6'~
-13-
methyl ethyl ketone oxime hydrochloride or MEKOHC).
Since MEKOHC is a liquid at room temperature, phase 17
is illustrated in the figure as a liquid phase he~vier
than phase 16. For other oxime hydrohalide by-products
(e.g. acetone oxime hydrochloride or cyc:lohexanone oxime
hydrochloride), phase 17 is a solid such that separation
vessel 15 is a centrifuge, filtration system or other
similar liquid/ solid separation device. Phases 16 and
17 are removed from vessel 15 continuously or intermit-
tently and further treated as described below. A repre-
sentative composition for phase 16 is ovler 40% organo-
silanes, about 40~ solvent, under 2% MEKOHC, under 2%
MEKO and minor amounts of alcohol, various by-products
such as dimers and trimers of product organosilanes. A
representative composition for phase 17 is over 95%
MEKOHC, under 2% solvent, under 2% organosilanes, under
2% MEKO and minor amounts of alcohols.
Phase 16 is removed from separation vessel 15
to treatment vessel 18, equipped with agitation, where
~0 it is treated with dry ammonia gas fed in stream 19 in
an amvunt sufficient to convert the MEKOHC to ME~O and
ammonium chloride. Residence times in treatment vessel
18 of only a few minutes are required, but longer times
may be used. The resultant thin slurry is withdrawn
25 from treatment vessel 18 in stream 20 to filtration
device 21 where the solid ammonium chloride is removed
from the liquid~ Periodically, the crude solid am~onium
chloride is removed fronl filtration device 21 as shown
by stream 22 for disposal or separation into organic and
3 0 inorganic materials. A representative composition of
the clarified stream 23 downstream of filtration device
21 is over 40% product organosilanes, about 40~ solvent,
under 0.01% MEKOHC, 3-4% MEKO and minor amounts of
alcohol and dimers and trimers of the product organo-
silanes.
The clarified stream 23 is fed to vacuumstripper 24 where it is separated at subatmospheric
pressure into a vapor stream 25 containing essentially
1~36~L7~
-14~
all of the solvent, MEKO and alcohol, and a liquid
bottom stream 26 containing the purified organosilane
product. Stream 26 may be again filtered to remove any
solids ~hat form upon solvent evaporation (e.g. precipi-
tated dimers and trimers) or may be l~sed as taken fromstripper 24. When the boiling point of the solvent
(hexane = 69C at 101 kPa) and MEKO (152C at 101 kPa)
is significantly lower than the product (some products
have boiling points over 150C at 101 kPa), a single
plate is sufficient for stripper 24. Stripper 24 pre-
ferably operates under vacuum. If such differences are
not present, more plates are required, and the product
may be taken as an overhead fraction.
Phase 17 in separation Yessel 15 (containing
mainly MEKOHC) is fed continuousl~y or intermittently to
neutralization vessel 30 equipped with agitation. Aque-
ous base (e.g. 17% ~aOH) is fed to vessel 30 in stream
31 in proportions producing in vessel 30 a suspension of
an aqueous phase containing saturated inorganic salt
(e.g. NaCl) and most of the alcohol present in phase 17
and an organic phase consisting of oxime compound
(MEKO). This slurry is fed in stream 32 continuously or
intermittently to a separation vessel 33 where it
quickly and easily separates into oxime phase 34 and
aqueous salt phase 35, both of which are removed. Aque-
ous phase 3~ is cleared of residual organics (e.g.
alcohols) in a conventional fashion and disposed of.
Oxime phase 34, containing some water, may be purified
in conventional fashion for use in a variety of
processes requiring dry oxime (e.g. for recycle to
stream 12) or used in wet form in other processes
(e.g. for the production of hydroxylammonium chloride).
The present invention is illustrated by
the following examples which, though conducted on a
laboratory scale, are easily transferable to processes
such as the one illustrated in Figure 1.
-15-
EXAMPLE 1
Reaction of MTCS:Ethanol:MEKO at 1:3:3_
In a 500 mL 3-necked flask fitted with a
thermometer, reflux condenser with drying tube, and a
dropping funnel was placed a solution of methyl ethyl
ketoxime (26.5 g) (0.3 mol) and absolute ethanol
(14.5 g) (0.3 mol) in anhydrous ethyl ether (200 g).
The solution was stirred using a magnetic stirring bar
with cooling in an ice-water bath. Maintaining the
temperature between 10 and 20C, methyl trichlorosila~e
(15 g) (0.1 mol) was added slowly and immediately a
two-phase system was produced. After stirring for 10
minutes at ambient temperature, the reaction mixture
was carefully transferred to a separatory funnei and the
two phases collected separately.
The top phase (219 g) was treated with ammonia
gas when a fine precipitate of ammonium chloride separ-
ated out. This was ~iltered off and the clear filtrate,
on removal of ether, gave a colorless liquid (19 g).
Analysis of this colorless liquid by gas chromatography
showed that it was 9l~ pure methyl triethoxysilane con-
taining small amounts of methyl diethoxy (methyl ethyl
ketoximo) silane (4.8%) and methyl bis-(methyl ethyl
ketoximo) ethoxysilane (1.4%). No methyl tris(methyl
ethyl ketoximo) silane was detected. The identity of
the product was confirmed by GC-mass spec.
The heavy bottom phase t37 g) was virtually
pure methylethyl ketoxime hydrochloride, which was
carefully neutralized with aqueous NaOH to recover the
oxime as a separate phase.
EXAMPLE 2
Reac~ion of MTCS:Isobutanol:MEKO at 1:3:3
.
The same apparat~s as in Example 1 was used
and methyl trichlorosilane (15.4 g) (0.1 mol) was added
with cooling and stirring to the solution c methyl
ethyl ketoxime (28.3 g) (0.32 mol), isobutanol (23.6 9~
(0.32 mol) in hexane (120 g). The temperature reached a
maximum of 35C during the addition. At the completion
., ~
~3~ 7~
-16-
of addition the two-phase mixture was stirred at ambient
temperature for 30 mint~es more. The phases were separ-
ated and the top phase (145.3 9) was ~reated with
am nia gas. The precipitated amonium chloride was fil-
tered off and the clear filtrate stripped of the solventand the colorless liq~id collected (27.2 g). Gas chrom-
atographic analysis of this mobile liquid showed that it
contained primarily methyl tri-isobutoxysilane (73.8%)
with methyl di-isobutoxy (methyl ethyl ketoximo) silane
(19.4~) and methyl bis-(methyl ethyl ketoximo)isobut-
oxysilane (0.6~) as the other significant components.
The product distilled at 85-90C at 3 mm Hg.
The identities of these compounds were con-
firmed by GC mass spec. analysis.
The bottom phase (39.8 g) of methyl ethyl
ketoximo hydrochloride was neutralized wi~h aqueous
sodium hydroxide to recover the ketoxime.
EXAMPLE 3
Reaction of MTCS:Isobutanol:MEKO at 1-4:3
The same apparatus as in Example 1 was used,
and the same procedure was followed as in Example 2.
The only significant diference was in the amount of the
reagents: isobutanol (35 g) (0.47 mol), methyl ethyl
ketoxime (~ g) (0.32 mol), methyl trichloro silance
25 (15 9) (0.1 mol), hexane (200 9).
The two phases were separated in a separatory
funnel and the clear top phase (233.8 9) was treated
with ammonia gas. A~ter filtering off ammonium chloride
the clear filtrate was stripped of hexane, and excess of
isobutanol and a colorless mobile liquid collected (26.5
9). Gas chrc,matographic analysis of this liquid showed
that it was g4.1% pure methyl tri isobutoxy silane with
only a small amount (4.6%) of methyl di isobutoxy
(methyl ethyl ketoximo) sila~e as the significant impur-
ity.
'~he bottom phase (43.7 9) of methyl ethylketoxime hydrochloride was worked up in the usual manner
with aqueous NaOH to recover methyl ethyl ketoxime.
~13~
EXAMPLE 4
Reaction of MTCS:Isobutanol:MEKO at 1:2:4
In a 500 mL 3-necked flask fitted with
thermometer, dropping funnel and reflux condenser
fitted with drying-t~be was placed a solution of methyl
ethyl ketoxime l35 9) (0~4 mol) and isob~tanol (14.8 9)
(0.2 mol) in hexane (160 g). This was stirred using a
magnetic stirring bar and maintained cold ~10-20C)
dring which methyl trichlorosilane ~15 g) (0.1 mol)
was added dropwise. After the addition was complete,
cooling was removed and stirring continued at ambient
temperature for 30 minutes more.
The two clear phases were separated using a
separatory funnel. The top phase of hexane solution
(186.7 g) was treated with ammonia gas for one minute
and the separated precipitate of ammonium chloride was
removed by filtration. The clear filtrate was then
stripped of the solvent under reduced pressure and a
colorless mobile liquid collected (26.5 g). Gas
chrcmatographic analysis of the liquid showed that it
contained primarily methyl di isobutoxy (methyl ethyl
ketoximo) silane (73.3~). The other significant com-
ponents were methyl tri isobutoxy silane (11.5~), methyl
tris ~methyl ethyl ketoximo) silane (6.2%) and methyl
bis-(methyl ethyl ketoximo) isobutoxysilane (1.0~).
The identity of these components were confirmed by GC
mass spec. The major product~distilled at 65-70C at
0.9 mm Hg.
The viscous bottom phase (37.9 9) of methyl
ethyl ketoxime hydrochloride was worked up with aqueous
sodium hydroxide to recover the oxime.
EXAMPLE 5
Reaction of DMDCS:Isobutanol:MEKO at 1:1:3_
The same apparatus as in Example 4 was used.
Dimethyldichlorosilane (12.9 g) (0.1 mol) was slowly
added with stirring and cooling to a solution of iso-
butanol (7.4 g) (0.1 mol) and methyl ethyl ketoxime
(26.1 g) (0.3 mol) in hexane (200 9). On completion
~36~t~
-18-
of addition the mixture was stirred for one hour and the
phases separated in a separatory funnel.
The top phase of hexane solution (219.2 9)
was treated with ammonia qas and the precipitated
ammonium chloride separated by filtration. The clear
and colorless filtrate was stripped of hexane and a
mobile liquid (20 g~ was collected. Gas chromatographic
analysis showed that it was dimethyl isobutoxy (methyl
ethyl ketoximo) silane (75.2%) toge~her with dimethyl
diisobutoxy-silane (17.8~) and dimethyl bis-(methyl
ethyl ketoximo) silane (7.0%) as minor components. GC
mass spec analysis confirmed the identity of the product
(B.P. 45-50C/0.7 mm Hg.).
The bottom phase (26.4 g) of methyl ethyl
ketoxime hydrochloride was neutralized with aqueous
sodium hydroxide as before to recover methyl ethyl
ketoxime.
EXAMPLE 6
Reaction of VTCS:Ethanol:MEKO at 1:2:4
The same apparatus as in Example 5 was used,
and vinyl trichlorosilane (16.2 y, 0.1 mol) was added
slowly with stirring and cooling to a solution of
ethanol ~9.2 g, 0.2 mol) and methyl ethyl ketoxime
(34.8 g, 0.4 mol) in hexane (190 g). After stirring
at ambient temperature for 30 minutes more, the two
phases were separated. The bottom phase of MEKO
hydrochloride (39.3 g) was neutrali~ed with aqueous
NaOH to recover MERO.
The top phase of the hexane solution ~209.8 9)
was neutralized with ammonia gas for 2 minutes and the
small amount o NH4Cl formed separated by filtration.
The clear filtrate was stripped of hexane under reduced
pressure to obtain a colorless liquid ~20 g). Gas
chromatographic analysis showed the liquid to be vinyl
diethoxy ~methyl ethyl ketoximo) silane (67.1%), vinyl
triethoxysilane (24.5%) and vinyl ethoxy bis-(methyl
ethyl ketoximo) silane ~8.4~). Less than 1% of vinyl
tris-(methyl ethyl ketoximo) silane was present.
~3~ 7~j
--19--
The identity of all the compounds was estab-
lished by GC-mass spec. analysis.
EXAMPLE 7
Reaction of MTCS:Isopropanol:MEKO at 1:2:4
In a 5 liter jacketed resin kettle fitted with
overhead stirring, thermometer and dropping funnel was
placed a solution of isopropanol (600 g, 10 mol) methyl
ethyl ketoxime ~1740 9, 20 mol) and hexane (2000 mL).
Cold water at +5C was circulated from a cooling bath
thro~gh the jacket and methyltrichlorosilane (750 9,
5 mol) was slowly added maintaining the temperature of
the reaction mixture between 20-25C. Addition was
completed in 45 minutes and with cooling water circ~-
lation stopped the mixture was stirred for an additional
15 minutes. The bottom phase of methyl ethyl ketoxime
hydrochloride was run off the bottom of the kettle and
collected (1940 g) as a viscous liquid. This was neu-
tralized with aqueous NaOH to recover the oxime.
The top phase ~2400 g) was treated with
ammonia gas from a cylinder for 2 minutes with stirring
and a thin precipitate of ammonium chloride was formed.
The solid was filtered off and the clear filtrate was
stripped of hexane at maximum temperature of 90C at 25
mm Hg to furnish a colorless mobile liquid (1198 g).
Gas chromatographic analysis showed that the liq~id was
primarily methyl diisopropoxy (methyl ethyl ketoximo)
silane (62.6~) together with methyl triisopropoxysilane
(19.2%) and methyl isopropoxy bis-~methyl ethyl
ketoximo) silane tl5.1%).
The structures of the compounds were confirmed
by GC-mass spec. analysis.
