Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~067090
The ob~ect o~ the pre~ent i~vention is ~ proces~ for
the manufa~ture of alkoxy~ila~es by esterlfi¢ation of ohloro-
~ilanes with alcohols.
~he esteriflcation of chlorosilanes generally takes
place according to the following reactionS,equation:
Rm SiC14 ~ n R'OH ~ ~ Si(ORl)nC14_m ~ n HCl.
In this equation R' ~tands for an alkyl radical with 1 to 11
C-atoms, m can take on values between O and 3 and n value~ between
1 and 4. R ~tands for H or an alkyl radi¢al with 1-11 C-atom~.
~he practical carrying out of this reaction causes
difficultie~, because the hydrochloric acid thereby re~ulting
in ~reat quantity dissociat~s not only the al~oxy group to alGohol
and chloro~ilane~ but also (especially in the presence of alkanol)
the hydrogensilane bo.nd with the by-productio~ of hydrogen and
formation of an alkoxysilane- and chlorosilane bond. Furthermore
the hydrochloric a¢id form~ with the added ~lkanols, chloro~lkanes
and ~ntermedlary water, which in it~ turn affects the chlorosilane
and alkoxy~llane by hydrolysi~. Because of th~ side reaction,
if certain process conditions are not observed, the desired
silane e~ter i~ mostly lost ¢ompletely.
Therefore several attempts have already bee~ made to
produce compounds of this klnd as economically as possible. The
problems, originally associated with the batch proces~es, of
the condensate formation a3 a re~ult of the mentioned s1de
reactions of the escaping h~drochloric acid with the aloohol~
introduced for the esterification, can indeed be avoided to a
~ large extent by u~ing modern batch method~. However there are
-~ limits to its tran~er to the field of large scale i~dustry,
e~pecially because o~ the dif~icult oontrol of the large amounts
3 of hydrochlori¢ acid in combi~ation with base materials which if
~ece~sary have low boil~ points, and of the quick and high
heat tranæfers necessary for the reliable carrying out of the
~ 067090
reaction not only in the reaction space but al90 in the e~haust
ga3 .
Continuous proce~se3 have already been suggested, in
which chloro~ilanesl iD fluid phase, are e~terified either i~ a
reactor with overflow, borrowed from the simplest batch proce~s,
or in several reactors conneeted in ~eries according to the method
of the ¢ounter- n ow principle. However, thi~ method haY the
dlsad~antage that the hydrochlorio acid is too 810wly and in-
completely removed. That leads to reverse dissociatioD~ of alread~
10 present ester groups and side reactions between the alcohols and
the hydrochlori¢ acid, with uDdesired hydrolysate ~o~matio~.
Another process describes the esterlfication of chloro~ilane~
with al¢ohol~ in the gas phase and utiliee~ temperatures, which
are above the boiling poiDts of all the sub~tanoe~ ¢oncerned
(base aDd end products).
~ he latterly mentioned pro¢ess however has a quite
particular disadvantage, because the hydrochloric acia present
in the system ls induced, as a result of the raised temperature,
to a particularly fast ~tart Or the known sid~ reaction~, in
particular therefore, re~ers~ dissociation, alcohol-dehydration
and hydrolysate formation.
~ he particular weaknesses of all the continuous e~ter-
ification processes described abo~e i8 that the ~eparation of
the hydrochloric acid from the reaction mixture is too slow and
lncomplete. It has also beeD sugge~ted that the hydrochloric
acid be blown out by the pas~ing over or through o~ inert gases
for example nitrogen, If neces~ary with the aid of a falling
ff lm evaporator, whereby an upper temperature limit may not be
exceeded. ~hi8 technique however also ha~ the considerable
disadvantage that the volume of exhaust ga~ from the hydrochloric
a¢id i~ lDcrea~ed; in thi~ way the los~es by e~aporation determin-
ed by the partial pressure of the products i9 unJu~tifiably
1067090
high, and re-~ing the hydroohlori¢ a¢id i~ praotically ruled
out.
Furthermore, with thi~ operation, powerful ¢ooling ~
device~ are required to reduce the e~cape of produot~ through
inert gas flow; in additio~ e~tremely dry gase~ are a requi~ite
for a method of this kiDd, a~ otherwise increa~ed siloxane
formation occur~.
It i~ al~o known to increa~e the exit velocity of the
hydrogen halide out of the reaction medium during the e~teri~ica-
tion proces~ by the introductio~ of benzol or benzlne ~olvents
: to the halogen ~lane, in order thus to reduce the above-mentlo~ed
formation of siloxanes. De~pite these mea~ures, not inconsider-
abls re~idue aciditie~ are left behind in the reaction product,
with the~e method~, which mu~t be eliminated as salts by the
addition of acid-binding means. ~his introduces the disadvantage
Or additional operatio~ proce~es such a~ filtration~ o~ the
raw ester and wa~hing out the salt~ for reducing the y~eld los~es.
Also the e~terification Or ¢hlorosilanes with aloohols
ln the prese~Gs of ¢hlorohydrocarbo~s is de~cribed, whereby the
introduction of textiary-aleoholic component~ i8 effected in the
presence of ami~es. However with thi~ method large amount~ of
: salt al~o oc¢ur, which must be remo~ed by additional process
~tep~ for thair reprocessing.
Now a process for the s~terification of ¢hlorosilane~
has been found, which 1~ characteri~ed in that the conYersion
takes place i~ the presence o~ chlorohydrocarbons and in the
absence of acid-binding mean3. These ~easure~ lead to a greater
simplificatioD of the proce~ and to an unexpected yield iDcrease.
~hi~ is true not only ~or primary but al80 for ~econdary aloohol3
and phenols.
Tha reaction take~ place in ac¢ordance w$th the aboYe-
~entioned equation. Suitable base material~ of the geDeral
1067~90
formula ~SiC14 m are for example triohloro~ilane, tetra¢hloro-
~ilan~, methyldichloros~lane, trimethylchlorosllane, methyl-
trichloro~ ne, ethyltrlchloro~llane, ethyldichlora~ilane,
n-propyldichloro~ilane, propyltrichloro~ilane, i~obutyldichloro-
silaDe, vinyldichloro~ilane, vinyltri¢hlorosilane, vinylmethyl-
dichlorosilane, dimethyldlchloro3ilane, propenyltrichloro~ilane,
allyltrichloro~ilane, 3-chloropropytrichlorosllane and ma~y
others. It appears from thi~ that R may ~tand not only for ~atu-
rated and unsaturated alkyl radicals with up to 11, preferably
up to 6 C-atom3, but al80 for hydrogen. The alkyl radical~ may
al80 be different, a~ for example ln the methylethyldlchloro~ilane
or methylphenyldichloro3ilane. Al~o phenyltrichloro~ilane may be
sub~tituted. ~he radical R may al80 be ~ub~tituted by halogen,
as for example in the chloropropyltrichloro~ilane, chloroethyl-
trichloro~ilane, to the methylchlorethyltrichloro~ilane or
CF3-CH2-SiC13 or al~o CF3-CH~-O-(CH2)3-SiC13.
Simple aliphati¢ alcohol3 such as for example methanol,
ethanol, n-propanol, ~-butanol, octanol come into consideration
as alcohol~ of the general formula R~OH for the production of the
silane esters, but al~o for example 2-methoxyethanol, 2-ethoxy-
etbaDol, tetrah~drofurfuryl al¢ohol, 2-methoxyathyldiethyleneglycol
ether or polyethyleneglycolmonoether.
The radi¢al R~ may therefore be a linear-chain or cyclic
alkyl radi¢al which is interrupted by heteroatoms such as -O- or
-~-. The corresponding ~e~ondary alcohols or phe~ols or mixed
aromaticaliphatic alcohol~, such as for example benzyl alcohol,
may al80 be introduced.
Compound~ ~uch as carbon tetrachloride, chloroform,
methylene chloride, dichloro ethane, dichloro ethylene, 1,1,1-
trichloroethane, trichloroeth~l~ne, perchloroethyle.ne, tetra-
chloroetbylene, tetrachloroethane can be considered as chloro-
hydrocarbons wh~ch may be u~ed.
-- 4 --
1067~:190
The chlorohydrooarbon~ w ed should be fluid under
normal conditions, and have boiling pointa below 150. The number
of C-atom~ i~ preferably 1-3; the hydrocarbon radical maJ not
only be ~aturated but ~180 unsaturated.
The ratio of chlorosilanes to chlorohydrocarbon during
the esterificatioD may vary wi~hin wlde limit~, mostly a ratio
chlorosilane/chlorohydrocarbon of 1/0.5-1 i8 sufncient for
a¢hie~ing neutral end products and maximum ~ields.
~ he amount of chlorohydrooarbons may be 0.5-3 times
as much as the halosilane added during the e3terification.
For example, ac¢ording to the invertion the following
product~ are obtalned: trimethoxysilane, triethoxysilane,
tetraethoxysllane, tris-2-methoxyethoxysilane, tetra-2-methoxy-
etho~ysilanes, methyldimethoYysilane, methyldiethoxysilane,
vlnylmethyldiethoxy~ilane, methyltriethoxysilane, ~inyltrieohoxy-
~ilane, ~inyltri-2-methoxyethoxysilane, 3-chloropropyltriethoxy-
~ilane and many others.
~ he oarrying out of the eoterification take~ pla¢e
a¢cordlng to generally known method~ of e~terification. Prefer-
; 20 ably, the chlorosilane i~ prepared with the chlorohydrocarbonand the alcohol 18 add~d i~ Bmall amount~ to the warmed mixture.
The amount of the alcohol to be added is dete i ned according
to the d~sired de OE ee o~ esterification. Tha reactlon is prefer-
ably e~fected at the boiling temperature of the silane/¢hlorohydro-
carbon mi~ture. A~ter separation o~ the solvent, preferably by
- distlllatloD, the de~ired e~ter i8 obtained with yields of up
to 99% with ~ery high purity.
A number of the mentioned e~ter compound8 of silicon
have acquired increaslng technlcal importance. For example some
9ilicic a¢id orthoe~ters are u~ed a~ binders for zinc du~t paint~
and in foundry proce~se~. Several organosilanee~ters are used
as bullding preservative agent~. A number of other organo~ilane-
~1~67090
esters and hydrogensilane ester~ have increasing technioalimportance for the ~ynthe3is of ~ery valuable organofunctional
silanes. ~urthermore, hydroge~silane esters are al~o of intere~t
~or semi-cQnductor chemistry.
EX~MPLE 1:
A 6-litre thre~-necked flask is placed in a mu~hroom-~haped
heating ~acket and i9 provided with a stirrer? a reflux conden~or
and a separati~g funnel.
1060 g (5 Mol) ~ - chloropropyltrichlorosllane i9 put into the
flask; after heating the fluid to 80, 930g (15.5 Mol) n-propanol
is added in amounts of 20 ml each, with ~trong agitation. After
4.5 hours the addition i~ ~topped. It is heated agal~ at 90
for a further 4 hours and then the raw produ¢t i8 distllled of~
in ~acuum (1-2 Torr - 101G). 1015 g (72%) of a colourless
produot 18 obtained. When one ml is pour~d into 100 ml wat~r,
wlth added indicator (methylorange), th~re is a strong acidic
reactlon.
EXAMPLE 2:
Apparatus identlcal to example 1,
zO 1060 g (5 Mol) ~-chloropropyltrichlorosilane i~ put in the flask
together with 900 ~1 tri¢hloroeth~lene. ~he cour~e of ester-
ification (15.5 Mol n-propanol) takes place as described in
example 1. ~fter removing the trichloroethylene by dist~llatioD,
a proportion of 98~ ~ -chloropropyl-tri-(propoxy)-silane i~
determined ga~chromatographically in the fluid in the flask.
When the ester i~ poured into water with added indicator
(methylorange) as in example 1, a ncutr~l reaction i~ reglstered.
EXAMP~E 3:
Apparatu~ identical to example 1,
1060 g (5 Mol)~ -ohloropropyltrichloro~ila~e i~ put;in the flask
with 900 ml carbo~ tetrachloride. The cour~e of the ester-
ifioation (15.5 Mol n-propanol) takes place as described in
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1a)67090
example 1 (reflux boiling o~ the ¢arbon tetrachloride). ~fter
the carbon tetrachlorlde has been removed by di~tillation! a
proportlon of 97.5% chloropropyltrlpropoxysilane i8 determined
gaschromatographic~lly in the product. A neutral reactlon 18
indicated when it i9 poured into water (with added methylorange).
EXAMP~E 4:
1060 g (5 m) ~-chloropropyltrichlorosilane is put in the flask
together with 2.7 1 trichloroethylene. The cour~e of ester-
ificatlon (15.5 Mol n-propanol) take~ pla¢e as described in
example 1. After the trichloroethylene i8 remo~ed by distillation,
a proportion o~ 98.6% ¢hloropropyltripropoxysilane i8 gaschromato-
graphi¢ally determined in the n a~X product. A neutral rea¢tion
is indicated ~hen the ester is poured into water (with added
ethylorange).
EXAMPLE 5:
; Apparatus identical to ~xample 1,
~ 785 g (5 Mol diethyldichloro~ilane) i~ put in the flask. The
; esterification process(l5.g Mol n-propanol) takes place as
desGribed in example 1. ~he raw ester i8 distllled of~ in ~acuum
(20 Torr (60). 725 g (71~) of a colourless product is obtained,
`~ which, as in example 1, ~hows a strongl~ acidic reaction when
added to water (containing methylorange).
EXAMPIE 6:
Apparatu~ identlcal to example 1,
785 g (5 Mol) diethyldichlorosilane i8 put in the flas~ together
with 2 1 tetrachloroethylene. ~he esterification (15.5 Mol
n-propanol) takes place as described in example 1. After the
tetrachloroethylene ha~ been removed by distillation, the flask
contents are analyzed gaschromatographically. A proportion of
97.2% diethyldlpropoxysilane is determined. When this i~ poured
into water (with added methylorange) a neutral reaction is
indicated.
~` 1067090
EXAMPLE 7:
Apparatus identical to example lf
745 g (~ Mol) methyltrichlorosilane ls put in the flask and i8
e~terified with 1680 g (15.5 Mol) benzyl alcohol as described in
example 1 (8tarting temperature: 60C; raised to 80-85C towards
the end of the addition of alcohol). ~he esterification product
i~ distilled off in vacuum (1-2 Torr, 120C). 1410 g of a
colourle~s fluid (72%) i8 obtained, whi¢h, when added to:~ater
(containing methylorange), produce~ a ~trongly acidi¢ reaction.
EXAMP~E 8:
Apparatus identical to example 1,
745 g (5 Mol) methyltrichlorosilane is put in the flask together
with 1900 ml tetrachloroethane and i~ esterified with 1680 g
(15.5 Mol) ben~yl alcohol as described in example 1. After the
removal of the chlorohydrocarbon by di~tillation, the flask -
contents are analyzed easchromatographically and a proportion of
98% methyltrlbenzyloxysilane is found. The vacuum-distilled
processing of the fla~k contents re~ults in 1750 g of a colourles~
~luid (96.5%), which when it i9 poured lnto water (with added
methylorange) give~ a neutral reaction.
EXAMPLE 9:
Apparatw identicPl to e2ample 1,
; 1060 g (5 Mol)~'-chloropropyltriohlorosilane is put in a flask
together with 1900 ml trichloroethylene and is e~terifled, as
de~cribed iD example 1, with 906 g (15,5 Mol) isopropanol.
After the removal of the trichloroethylene by distillatlon, a
proportion Or 97.8% chloropropyltrii30propo~y~ilane is found
gaschromatographioally i~ the flask fluid, A neutral reaction
is~hown when it i~ poured into water (with added methylorange),
EXAMPIE 10:
Apparatu~ identical to example 1,
815 g (5 ~ol) ethyltrichloro6ilane i~ put in the flask. ~he
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~067090
esterl~ication i~ carried out as de~cribed in example 1, with
1180 g (15.5 Mol) methoxyethanol. The e~terification produ¢t
is then analyzed ga~chromatog~aphically. A proportioD of 78~
ethyltri -(methoxy-etho~y)-silane is found; al80 several mixed
ester~ are registered, which are formed by the separation of the
methoxyethanol to methanol and chloroethanol.
EXANP~æ 11:
Apparatus identical to example 1,
815 g (5 Mol) ethyltrichlorosilane i8 put in the flask tog~ther
with 900 ml tetrachloroethylene and i8 e~terified, as described
in test 1, with 1180 g (15.5 Mol) metho~yethanol. After the
tetra¢hloroethylene has been removed by distillation, the ~lask
contents are analyzed by gas chromatography. A proportion of
97.9% ethyltris-(methoxyethoxy)-silane is determined. Mixed
esters are not registered. After this the fla~k ¢ontents are
processed by vacuum di~tillatioD (1-2 Torr; 110C). 1355 g
ethyltris-tmethoxyethoxy)-~llane (96~ obtained, whi¢h shows a
Deutral rea¢tion when added to water (¢ontaining methylorange).
~XAMPIæ 12:
~o Apparatus identical to examplc 1,
850 g (5 Mol) ~ilicon tetrachloride i9 put iD the ~la~k together
with 1900 ml tetrachloroethylene. The e~terification takes
place as described in example 1, with 1974 g (21 Mol) phenol.
After the tetrachloroethyl~ne and ~uperfluous phenol~ have been
removed by distlllation, the ~lask product i8 analyzed by gas
chromatography. A proportlon of 98.7~ tetraphenoxysilane i8
recorded.
When the product i8 added to water (containing methy-
lorange) a neutral reaction is shown.
_ g _
