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Патент USA US3028330

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United States Patent
Patented Apr. 3, 1962
The electrolyte mixture usually contains from 5-95 per
cent of the alkali metal aluminum methyl compound.
Best results are obtained using a concentration of the
Paul Kohetz and Richard C. Pinkerton, Baton Rouge, La.,
alkali metal aluminum methyl compound of from 10-75
assignors to Ethyl Corporation, New York, N.Y., a cor- 5 mole percent. A preferred concentration of the alkali
poration of Delaware
metal aluminum methyl compound in the electrolyte mix
No Drawing, Filed Feb. 1, 1960, Ser. No. 5,672
ture is from about 20—-65 mole percent. In general, the
4 Claims. (Cl. 204—59)
electrolyte mixture should have a melting point below
about 150° C. for manufacture of alkyl tin compounds
This invention relates to the manufacture of tin ongano
compounds and more particularly to the manufacture of 10 and the most preferred electrolytes have melting points
tin tetraorgano compounds and especially tin tetraal-kyl
below about 100° C. The pure sodium aluminum tetra
methyl, for example, has a melting point in excess of
compounds, such as tin tetraethyl.
240° C. but the addition of relatively small quantities of
Tin alkyl compounds are highly useful as intermediates
the sodium or potassium aluminum tetraethyl, or higher
in making stabilizers for polymeric materials, such as
vinyl chloride or for stabilising components for liquid 15 organo compounds, sharply reduces the melting point of
the mixture.
chlorinated hydrocarbon compounds such as are used
The above process involves exceptionally simple tech
in transformer dielectric liquids or the like. Heretofore,
niques and apparatus and provides high yields of the tin
the accepted method for making tin alkyl compounds,
alkyl compounds, in essence, directly from tin, hydrogen,
such as tetrabutyl tin, has been the reaction of stannic
chloride by the Grignard process, i.e., reacting the stannic 20 and ole?n. The tin metal is converted at the anode to tin
organo compounds and the electrolyte, in the manufacture
chloride with butyl magnesium chloride to form tetrabutyl
of such products, can be regenerated, either periodically
tin according to the following equation:
or continuously, by reaction with an ole?n and hydrogen.
The process is capable of extremely high production ca
Sodium tin alloys have been proposed for manufacture of 25 pacities because it can be operated at high current densi
tetraalk-yl tins by reacting with lower alkyl chlorides, but
ties, and this is practical because of the very high con
this type of process is relatively ine?icient in that a pre
ductivity of the complex electrolyte. The process can be
ponderant proportion of the tin metal originally fed, as
conducted at these high current densities at temperatures
alloy, is released as elemental metal and must be recovered
well below the thermal decomposition temperature of the
and recycled. Accordingly, a signi?cant need has existed 30 tin alkyl products. This good conductivity also materially
for an eifective and economical process for the production
reduces the problem of heat removal from the cell. A
of tin hydrocarbon compounds.
particularly surprising feature of this invention is that
the tin alkyl products contain only minor proportions of
It is accordingly an object of this invention to provide
an improved process for the manufacture of tin tetra~
methyl groups when the electrolyte contains R groups in
organo compounds and especially tin alkyl compounds, 35 addition to the methyl groups, but instead the methyl
such as tin tetraethyl.
Another object is to provide an
groups are recovered as aluminum-containing compounds
electrolytic process capable of producing substantial quan
tities of tin alkyl compounds in a relatively small elec
which can be readily converted to the complex alkali
metal aluminum methyl compound and recycled to the
trolytic cell. Still another object is a process in which the
electrolytic cell. The aluminum-methyl by-prouct (with
tin alkyl products can be readily separated from the elec- 40 out alkali metal) has a materially lower boiling point than
trolyte and by-products by simple and economical tech
the tin alkyl compound and thus can be readily separated
niques and in which the by-product can be regenerated and
from the tin organo product. Essential functions of the
returned to the cell.
alkali metal aluminum methyl compound, in other words,
These and other objects of the invention are obtained
are to provide high conductivity to the system and at the
if the electrolyte contains an alkali metal aluminum 45 same time form an aluminum-containing by-product which
methyl compound and especially an alkali metal alumi- q
can be readily separated from the tin organo product. As
num tetraalkyl in which at least one of the alkyl ‘groups is
will be seen from the following discussion, through regen
a methyl group. An especially desirable electrolyte for
eration of the alkali metal aluminum alkyl, the only raw
carrying out the process of this invention comprises a -
materials necessary for this process are metallic tin, ole?n
mixture or complex of an alkali metal aluminum methyl 50 and hydrogen. When using the mixed electrolyte, the
compound with an alkali metal aluminum tetraalkyl or
aluminum methyl compound is formed in from 5-30 per
tetraaryl, the organo groups of the latter compound con
cent of the total product and in some cases up to about 50
taining from 2 to about 12 carbon atoms.
percent and can be recovered as a second product or con
More speci?cally the process for manufacture of the
verted back to the alkali metal-containing compound for
tin alkyl compounds in accordance with this invention 55 reuse in the process.
comprises passing an electrolyzing current from a tin
The reaction of the present process can be illustrated,
anode through an electrolyte comprising an alkali metal
using the mixed electroltye, as follows:
aluminum tetraorgano compound having the formula
wherein M is an alkali metal, R is selected from the group
wherein M, Me, and R are as de?ned above. The alumi
num trialkyl can be separated from the tin tetraorgano
from 2 to 12 carbon atoms, and x is an integer of from 1
compound by distillation or by chemical means. In addi
to 4 inclusive. An especially preferred embodiment of
tion, some methyl-containing aluminum compounds are
this invention relates to the manufacture of tin alkyl prod- 65 formed which may, under certain conditions, react with
ucts using a mixed complex having, in addition to the alkali
the AlR3 to form mixed organo compounds. A suitable
consisting of alkyl and aryl groups, each group containing
metal aluminum methyl compound, another alkali metal
chemical method of recovering the tin organo products
aluminum compound in which all of the organo groups
and regenerating the aluminum compound is to react the
contain from 2 to 12 carbon atoms. A11 especially pre
aluminum compound with an alkali metal boron com
ferred electrolyte contains more than one alkali metal, e.g. 70 pound in accordance with the following equation:
both sodium and potassium or sodium and lithium or all
three metals.
+ BRa
sodium boron tetraethyl at a temperature of 100° C. to
produce the corresponding sodium aluminum alkyls and
the corresponding alkyl boron compounds. The latter
The complex can then be regenerated by the following
are gases at reaction temperature and can be readily sep
arated from the mixture. The sodium aluminum tetra
alkyl complex is readily separated from the tin alkyl
products by ?ltration and can thereafter be recycled to
As discussed above, it is convenient to carry out the
electrolysis of this invention using an electrolyte con
taining both an alkali metal aluminum tetramethyl and
an alkali metal aluminum tetraalkyl in which the alkyl
contains at least 2 carbon atoms. It is to be recognized
the electrolytic cell.
The tin hydrocarbon product liquid from the fore
going example consistcd of predominant quantities of tin
tetraethyl, with minor quantities of tin alkyl compounds
that the electrolyte can contain two or more methyl-con
smaller proportion of tin alkyl compounds of ditin types,
taining compounds, such as sodium aluminum methyl tri
e.g. hexaethyl ditin.
ethyl, sodium aluminum dimethyl diethyl and sodium 15
Example 11
Example I is repeated except that 25 mole percent of
potassium metal is added to the electrolyte to displace
having appreciable methyl radicals therein and an even
aluminum trimethylethyl, and especially mixed com
pounds of two or more alkali metals.
The present process can be carried out over an ex
the corresponding amount of sodium metal. In this
electrolysis the current density in amperes/sq. cm. is
The upper temperature at the anode is 20 greater and the anode ef?ciency is of the same order of
ceedingly Wide temperature range, generally from 0 to
about 200° C.
sometimes limited by the decomposition temperature of
‘the tin tetraorgano product. Accordingly, with tin tetra
ethyl as a predominant product component, it is usually
desirable to maintain the temperature below about 100
Example III
Example I is repeated except that the electrolyte con
25 sisted of 3 moles of sodium aluminum tetraethyl and 1
to 110° C.
mole of sodium aluminum tetrarnethyl. Comparable
anode ef?ciency and current density are experienced.
Such solvents can be either miscible or non-miscible with
Example IV
the electrolyte. Typical examples of suitable extractants
except that 10 mole percent
are aliphatic and aromatic hydrocarbon liquids. Excel
potassium is added to displace a corresponding quantity
lent results are obtained with such extractants as kerosene
of sodium, providing an electrolyte containing both so
and mineral oil used in a concentration of from about 25
In some cases it is desirable to use a solvent for the
tin organo compound, directly in the electrolysis cell.
to 75 percent of the tin tetraorgano product formed.
ium and potassium.
In this instance, a higher anode
e?iciency is achieved at a comparable current density.
Normally, the electrolysis is conducted at or near at
The following tabulated examples are carried out in a
mospheric pressure. However, a pressure of inert gas 35
similar fashion to Example I. The product in each in
stance is a tin alkylproduct liquid, predominating in the
tetraalkyl corresponding to the longer alkyl group present
in the electrolyte mixture. In addition to the principal
fect distillation of the tin organo compound and/or the
aluminum compound from the cell during the electrolysis. 4O component of the product, minor components present in
clude the dialkyl tin compounds and some small propor
The following are typical examples of the process of
such as nitrogen can be employed when desired, especial
ly to assure an oxygen and moisture-free system. In some
cases, it is desirable to employ a reduced pressure to ef
this invention, all parts being given in parts by weight.
tion of di-tin compounds, illustrated by hexaethyl distan
nane. The alkyl groups in the tin organometallic products
are predominantly the higher alkyl groups, but a small
A closed cell was provided with an annular copper 45 proportion of methyl radicals occur, of from 5 to 25 per
cent‘ of the total alkyl rgoups. In Example VIII, how
cathode and an axially positioned tin anode. To this cell
ever, all the alkyl groups in the product are methyl
was added an electrolyte containing equimo-lar propor
tions of sodium aluminum tetramethyl and sodium alumi
Example I
Solvent or Extractant
N 0.
based on tin-
° 0.
____ __
KAl(i-pr)t _________ __
Tin tetraisopropyl.
NaAlMe4_ ____ NaAl(OsH5)4___
0. 1
Tin tetraphenyl.
LiAlMe; ____ __
0. 3
The tetramethyl.
Tin tetraethyl.
N aAl(CsH11)4_ _
_ RbA1Me4__-__ NaAl(OH3)4.
NaAlMel~ _ ___
CsAlEtl ____ __
Tin tetraoctyl.
num tetraethyl.
The cell was heated to a temperature
Example X
of approximately 100° C. and a 3.8 volt potential was 65
Example I is repeated except that the electrolyte con
‘applied across the electrodes. The current density in
sists of sodium aluminum tetrarnethyl, potassium alumi
amperes/sq. cm. Was 0.25. The anode e?iciency was ap
num tetraethyl, and lithium aluminum tetraethyl in equi
proximately 80 percent. Tin alkyl compounds were pro
duced at the anode and formed a separate phase from
molecular proportions. In addition, mineral oil (80
Weight percent of the tin alkyl product) is employed in
the electrolyte. The product was drained by gravity from 70 the electrolyte as an extractant to aid in the removal of the
the cell. Sodium metal was deposited at the cathode dur
ing the electrolysis and this was also removed as a liq
uid from the cell. The methyl and ethyl aluminum by
tin alkyl product.
The alkali metal aluminum methyl compounds can be
prepared in one of several ways. A convenient process
involves the displacement reaction of the elemental alkali
products, mixed with the tin alkyl product compounds
andminm” quémities of electrolyte, are then reacted with 75 metal with aluminum trimethyl forming the correspond
ing alkali metal tetramcthyl. These compounds can also
be prepared by the addition reaction of aluminum tri
methyl and alkali metal alkyl compounds, or contrari
wise, aluminum trialkyls with sodium methyl. A par
ticularly suitable method for the mixed alkyl compounds 5
is the reaction of an ole?n, e.g. ethylene with an alkali
stituted benzene and naphthalene compounds. In some
cases the ethers can be used, especially the glycol ethers,
such as ethylene glycol dialkyl ethcrs, diethylene glycol
dialkyl ethers and triethylene glycol dialkyl ethers, where
in the alkyl group contains from 1-6 carbon atoms.
We claim:
metal aluminum alkyl hydride. Likewise, the complex
1. A process for the manufacture of tetraethyltin which
comprises passing an electric current through an anode
methyl compound can be made by reaction of an alkyl
containing tin and an electrolyte containing equimolar
halide with an alkali metal and trimethyl aluminum.
The alkali metal aluminum tetraorgano compound '10 proportions of sodium aluminum tetramethyl and sodium
aluminum tetraethyl at a temperature of about 100° C.
(the organo group containing 2 or more carbon atoms)
and a current density of 0.25 amperes per square cen
can be made by analogous processes. That is, the alkali
metal can be reacted directly with the aluminum trior
2. A process for the manufacture of tetrahydrocarbon
gano compound, e.g. sodium reacts with triethyl a1umi~
num to form sodium aluminum tetraethyl and metallic 15 tin compounds, the hydrocarbon radicals thereof pre
dominating in radicals of at least two carbon atoms,
aluminum. Likewise, sodium ethyl and other alkali
comprising passing an electric current through an electro
metal organo compounds will react directly with the alu
lyte and a tin containing anode, said electrolyte consisting
minum triorgano compound to form the complex as an
essentially of alkali metal aluminum tetrahydrocarbon,
addition product. The corresponding organo halides will
also react with the alkali metal and aluminum triorgano 20 the hydrocarbon radicals in said electrolyte including
from 5 to 95 percent methyl groups.
compound to form the complex, for example, sodium re
3. A process for the manufacture of tetraalkyl tin
acts with ethyl chloride and aluminum triethyl to ‘form
comprising forming an electrolyte from an alkali metal
sodium aluminum tetraethyl. A particularly desirable
aluminum tetramethyl and alkali metal aluminum tetra
method of preparing the alkyl complexes is the process
discussed above with reference to regeneration of the 25 ethyl, the alkali metal aluminum tetramethyl being in
proportions of from about 5 to 95 mole percent, and
trialkyl aluminum electrolyte. Trialkyl aluminums, e.g.
charging to an electrolytic zone, and electrolyzing by
trimethyl aluminum or triethyl aluminum, will react with
passing an electric current therethrough and through a tin
an alkali metal hydride such as sodium hydride to form
the corresponding complex hydride, e.g. sodium alumi
anode in contact therewith and'forming thereby tetra
num triethyl hydride, which can thereafter be reacted 30 alkyl tin, wherein the alkyl groups thereof predominate
in non-metal groups, and removing said tetraalkyl tin
with a suitable ole?n, as discussed above, forming sodium
from the electrolysis zone.
aluminum tetraethyl. All of the above preparation re
4. The process of claim 3 wherein the alkali metals of
actions can be carried out at temperatures from about 0°
the electrolyte compounds are different.
C. to about 150° C.
Normally, solvents are not employed in the electrol— 35
ysis system of this invention since they tend to reduce
the conductivity of the electrolyte. However, when they
are desired for certain purposes, such as to provide a
more ?uid medium, it is best to employ hydrocarbons,
especially aromatic hydrocarbons which are unreactive 40
References Cited in the ?le of this patent
Ziegler et al. .._.__- _____ __ Aug. 26, 1958
Australia ____________ __ Apr. 24, 1958
with the reactants, products and electrolyte. Particularly
suitable solvents are toluene, the xylenes and other sub
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