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Патент USA US2406605

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2,406,605
Patented Aug. 27, 1946
UNITED STATES ‘PATENT OFFICE
2,406,605
_
HYDROGENATION OF HALOGENOSILAN ES
Dallas T. Plurd, Schenectady, N. Y., assignor to
General Electric Company, a corporation of
New York
No Drawing. Application March 15, 1945,
Serial No. 582,998
15 Claims. (Cl. 260—607)
The present invention relates to the hydro
genation-of halogenosilanes. It is particularly
concerned with a method of substituting hydro
gen atoms for at least some of the silicon-bonded
halogen atoms in a highly halogenated chloro
silane to obtainthe corresponding hydrogen com
pounds.
..
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_
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.
.
'- Example 1
, The vapor of silicon tetrachloride together with
hydrogen gas in a mol ratio of 1:1 was passed
l
" At. the present time the most readily avail
able silanes, for commercial use, are silicon tetra
chloride and, in recent years, the hydrocarbon
2
In order that those skilled in the art better
may understand how the present invention can
be. carried into e?ect the following illustrative
examples are given:
over 20 mesh aluminum granules at 400° and
10
substituted halogenosilanes, such as‘ the methyl
the e?iuent products condensed by means of a
Dry-Ice condenser. A portion of the condensate
was hydrolyzed in water and the hydrolysis 'pro
chloros'ilanes, in which all of the silicon bonds are
connected either to hydrocarbon radicals orehal
ogen atoms,v Due to the increased commercial
duct treated with dilute sodium hydroxide solu- '
tion.v There was vigorous gas evolution showing
the presence of substantial amounts of Si-bonded
interestginsilicon chemistry resulting from the 15 hydrogen. ' A distillation of the liquid condensate.
introduction of rpolysiloxan'e resins, ?uids,.vetc.,
revealed the presence of about 3-5% of dichloro
there has been an increased .demandffor com
silane, SiI-IzCla, and 25% of trichlorosilane,
mercial quantities. of other less readily availablev
SlHClz, the remainder being largely unreacte'd
silanes-and silane derivatives such asthose in
silicon
tetrachloride. ‘Any silane, SiH4, formed
which. allor part of the silicon-bonds are'con 20 during the reaction was of course too volatile to
nected to-hydrogen. The present invention has
becondensed at the temperature of dry ice.
as its principal object the preparation of silane
Einample 2
derivatives containing ySi-bonded hydrogen from
' The vapor of methyltrichlorosilane (density:
the more highly halogenated silanes-particularly
from, halogenosilanes containing at least three
1.27) together with hydrogen gas in 1:1 mol
Si-bonded chlorine or bromine atoms. A more
ratio was passed over a 4-1 mixture of 20 mesh
speci?c object of the present invention is to pro
aluminum granules and 200 mesh copper powder‘
at a temperature of 450° 0. Subsequent experi
gen atoms of_-a halogenosilane can be replaced
ments indicated that the copper may b-e‘omitted
by hydrogen to form the corresponding hydrogen 30 and that its presence has no obvious effect on
the course of the reaction. The product con
Brie?y described, these and other objects which
densed by a water-cooled condenser had a density
of 1.21. A portion of this product was hydrolyzed
will appear hereinafter are attained in. accord
ance with the present invention by bringing a
and the presence of Si-bonded hydrogen in the
gaseous ‘mixture of a highly halogenated silane 35 resulting gel was qualitatively shown by the vigor
videv a method whereby one or more ofv the halo
compounds.
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-
.
'
,
and hydrogen or a hydrogen halide, particularly
ous gas evolution when the hydrolyzate was
treated with dilute alkali. Distillation of the re
action product' revealed the presence of approxi
the ‘chloride or bromide, into contact at an ele
vated temperature with a metal selected from the
group consisting of aluminum, magnesium and
zinc_.,v Examples of suitable halogenosilanes are
silicon tetrachloride, silicon tetrabromide. the tri
chloroe and, tribromo-silanes, the methyl tri
chloro-l and! tribromo-silanes, etc“ ,The silane
mately 5% of‘ methyl ‘dichlorosilane, CHsI-ISiCh.
'
hydrogen gas in 122 mol ratio was passed over
granular zine at 350-400". A liquid product was
'productsg‘enerally.comprise a mixture of some
condensed from the effluent gas mixture by means
.of- a Dry-Ice condenser. A portion of the con
ofethe ‘starting material, the less halogenated
silanes such as the mono-, di- and tri-halogen
ated silanes and, in some cases, the completely
densate was hydrolyzed in water to give‘a gel
which upon treatment with alkali solution pro
hydrogenated materialssuch as silane, SiH4.. The
metal .islco'nverted, to its halide during the reac
tion, probably through the- intermediate forma
tion‘ofajhydride which reacts with the halogeno
silane or possibly by'the directv reduction of sili
con-halogen ~.bonds under the. conditions of the
Example 3
> :A mixture of- silicon tetrachloride vapor and
duced a vigorous evolution of gas.
50
,A distil
lation of .the product revealed the presence
of-volatile compounds boiling below the boiling
point of. silicon tetrachloride. When these low
boiling compounds were treated. with dilute alkali
reaction (leaving. free silicon bonds 7for the for
the gas evolution was much more vigorous than
earms pr;
inthe. case of the gel.
bands»
.
V
2,406,605
3
4
Similar results were obtained when granular
magnesium was substituted for the zinc employed
in Example 3.
Example 4
least some of the halogen atoms in a halogenated
silane containing at least three Si-bonded halo
gen atoms which comprises contacting a mixture
of the vapors of said halogenated silane and a
material selected from the class consisting of
hydrogen and hydrogen halides at an elevated
temperature with a metal‘ selected from the class
Methyltrichlorosilane in vapor form (density:
1.27) together with hydrogen chloride gas was
passed in 2:1 ratio over aluminum granules at
350°. A liquid product of density 1.25 was con
densed from the reaction products by means of a
consisting of aluminum, magnesium and zinc.
3. The method of substituting hydrogen for at
10
least some of the chlorine atoms in a chlori
Dry-Ice condenser. Hydrolysis of a portion of
nated silane containing at least three Si-bonded
this product gave a gel which upon treatment
chlorine atoms which comprises bringing a mix
with alkali solution reacted with a vigorous evolu
ture of the vapors of said chlorinated silane and
tion of gas. Distillation of the product’ revealed
a material selected from the class consisting of
the presence of compounds more volatile than
methyltrichlorosilane, which compounds. were 15 hydrogen and hydrogen chloride into contact with
aluminum at an elevated temperature.
found to contain larger amounts of Si-bo-nded
4. The method of substituting hydrogen for
hydrogen than the gel.
at least some of the chlorine atoms in a chlori
nated silane containingat least three Si-bonded
20 chlorine atoms which comprises contacting a mix
Example 5
A mixture of vapors of silico-chloroform,
SiI-IC13, and hydrogen gas in 1:3 ratiowas passed
over aluminum granules at 350°. A reaction
ensued with the formation of‘ aluminum chloride.
Liquid product Was collected in a series of con
densers consisting of a Dry-Ice condenser fol
lowed by a liquid-air condenser. Distillation of
the combined condensates yielded about 1—2% of
ture of the vapors of said. chlorinated silane and
a material selected from the class consisting of
hydrogen and hydrogen chloride at an elevated
temperature with a metal selected from the class
25 consisting of aluminum, magnesium and zinc.
5. The method of substituting hydrogen for
.at least some of the chlorine atoms in a chlori
nated silane containing at least three Si-bonded
monosilane, SiHii; l-2% of monochlorosilane,
chlorine atoms which comprises bringing a mix
SlI-IsCl; and 10-15% of dichlorosilanaSiHzClz, 30 ture of the vapors of said chlorinated silane and
the remainder being largely unreacted silico
chloroform.
a material selected from the class consisting of
hydrogen and hydrogen chloride into contact with
It will be understood, of course. that‘the inven
zinc at an elevated temperature.
tion is not limited to the speci?c reactants, pro
6. The method of substituting hydrogen for at
portions and reaction conditions set forth in the 35 least some of the halogen atoms in a silicon tetra
above examples‘. The bromosilanes, such as sili
halide which comprises contacting a mixture of
con
tetrabromide,
tribromosilane,
methyltri
bromosilane can be reacted with hydrogen or a
hydrogen bromide or chloride in the presence of
the vapors of said silicon tetrahalide and a mate
rial selected from the class consisting of hydrogen
and hydrogen halides at an elevated temper
one or more of the designated metals in the same 40 ature with a metal selected from the class con
manner as the chlorosilanes to- form correspond
sisting of aluminum, magnesium and zinc.
ing products in which some of the Si-bonded
'7. The method of substituting hydrogen, for at
least some of the chlorine atoms in silicon tetra
Although the invention is not limited to any
chloride which comprises contacting a mixture
particular reaction temperatures, best results ap 45 of the vapors of silicon tetrachloride and a mate
pear to be obtained at temperatures ranging
rial selected from the class consisting of hydrogen
between 300 and 500° C., the preferred tem
and hydrogen chloride at an elevated temperature
perature depending to some extent on the particu
with a metal selected from the class consisting
lar combination of reactants employed. As the
of aluminum, magnesium and zinc.
substitution of hydrogen for Si-bonded halogen 50
8. The method of substituting hydrogen for at
is not quantitative, the rnol ratio of hydrogen or
least some of the chlorine atoms in a chlorinated
hydrogen halide to halogenosilane should equal
silane containing at least three Si-bonded chlo
and preferably exceed that calculated as neces
rine atoms which comprises contacting a mixture
sary to form the desired product. The unre
of the vapors of said chlorinated silane and a
acte'd starting materials can, of course, be recir 55 material selected from the class consisting of
culated to increase the overall yields of the de
hydrogen and hydrogen chloride with aluminum
sired products. When the metal is in a granular
at an elevated temperature of from 300 to 500° C.
state, or in the form of shavings and the like,
9. The method of substituting hydrogen for at
beter control of the reaction can usually be ob
least some of the halogen atoms in a methyltri
tained than when the metal is in a ?nely divided 60 halogenosilane which comprises contacting a
state.
mixture of the vapors of said trihalogenosilane
What I claim as new and desire to secure by
and a material selectedfrom the class consist
Letters Patent of the United States is:
ing of hydrogen and hydrogen halides at an
1. The method which comprises contacting a
elevated temperature with a metal selected from
mixture of (1) a halogenated silane having 65 the class consisting. of aluminum, magnesium and
Si-bonded halogen atoms which are replaceable
zinc.
by hydrogen and (2) a material selected from
10. The method of substituting hydrogen for
the class consisting of hydrogen and hydrogen
at least some of the chlorine atoms in a trichloro
halides, in the vapor state and at an elevated
silane which comprises, contacting a mixture of
temperature, with a metal selected from the class 70 the vapors of said trichlorosilane and a material
consisting of ‘aluminum, magnesium and zinc,
selected from the class consisting of hydrogen
thereby to replace at least some of the halo-gen
' and hydro-gen chloride at an elevated temper
atoms of the said halogenated silane with hy-'
ature with a metal selected from the class con
bromine atoms have been replaced by hydrogen.
drogen.
sisting of aluminum, magnesium and zinc.
2. The method of substituting ‘hydrogen for at 75
11. The method of substituting hydrogen for
' 2,406,605
5
at least some of the chlorine atoms in silicon
tetrachloride which comprises contacting a mix
14. The method which comprises bringing into
contact at an elevated temperature (1) a vapor
ous mixture of hydrogen and a chlorinated silane
having Si-bonded chlorine atoms which are re
placeable by hydrogen and (2) a metal selected
from the class consisting of aluminum, mag
nesium and zinc thereby to replace at least some
of the chlorine atoms of the said chlorinated
silane with hydrogen.
15. The method which comprises bringing into
10
ture of hydrogen and the vapors of silicon tetra
chloride in a mol ratio of at least 1:1 with granu
lar aluminum at a temperature of from 300 to
500° C.
12. The method of substituting hydrogen for
at least some of, the chlorine atoms in silicon
tetrachloride which comprises contacting a mix
ture of hydrogen and the vapors of silicon tetra
contact at an elevated temperature (1) a vapor
chloride in a mol ratio of at least 1:1 with granu
ous mixture of hydrogen chloride and a chlori
lar zinc at a temperature of from 300 to 500° C;
nated silane having Si-bonded chlorine atoms
13. The method of substituting hydrogen for
which are replaceable by hydrogen and (2) a
at least some of the chlorine atoms in methyl
trichlorosilane which comprises contacting a mix 16 metal selected from the class consisting of alu
minum, magnesium and zinc thereby to replace
ture of hydrogen and the vapors of methyltri
at least some of the chlorine atoms of the said
chlorosilane in a mol ratio of at least 1:1 with
chlorinated silane with hydrogen.
granular aluminum at a temperature of from 300
to 500° C.
‘
'
DALLAS T. HURD.
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