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Патент USA US2098206

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2,098,206
Patented Nov. 2, 1937
ATENT OFFICE
NETED ST
2,098,206
7
MANUFACTURE OF ALCOHOLS
Walter H. Hartung, Lansdowna, Pa., William G.
Young, Los Angeles, Calif., and Frank S.
‘ Crossley, Philadelphia, Pa., assignors to Sharp
& Dohme, Incorporated, Philadelphia, Pa., a
corporation of Maryland
No Drawing. Application June 19, 1935,
Serial No. 27,348
11 Claims.
This invention relates to the reduction of alde
hydes to the corresponding alcohols and more
particularly to the reduction of unsaturated alde
hydes, such as crotch-aldehyde, cinnam-alde
hyde, etc., to the corresponding unsaturated al
cohols.
.
Various processes have been proposed for the
reduction of aldehydes to alcohols, but only a
limited number of methods have been proposed
ll‘, for the reduction of aldehydes having an un
saturated radical, for example a vinyl group or
a substituted vinyl group, where it is not desired
to reduce the unsaturated group; and the meth
ods heretofore proposed have not, according to
13 our experience, proven satisfactory. It has been
proposed for example to reduce croton-aldehyde
by means of a zinc-copper couple; but we have
found that this method gave only low yields and
a product contaminated with butyl, that is hy
, drogenated or reduced, crotyl alcohol.
It has
also been proposed to reduce unsaturated alde
hydes by means of aluminum ethoxide and chlor
magnesium ethoxide; but such methods result in
the oxidation of the ethoxy group to acetalde
0;, hyde; and we have found the yields obtained by
such methods were small.
'
We have found that unsaturated aldehydes,
for example, croton-aldehyde, can be reduced to
the unsaturated alcohols, forexample crotyl al
391001101, and a product obtained satisfactory in
both yield and purity, by carrying out the reduc
tion with the use of secondary alkoxides of
aluminum, particularly, aluminum isopropoxide.
Crotyl alcohol, a homolog of allyl alcohol, is a
, valuable product for use as an intermediate and
for other purposes; and we have found that this
alcohol can be readily prepared with satisfactory
yield and of satisfactory purity by the present
process. Other unsaturated alcohols, such as
those hereafter referred to, can be similarly pro
duced from the corresponding unsaturated alde
hydes.
.
The reducing agents used in the present proc
ess are secondary metallic alkoxides, such as
(o1. 260-156)
ary butoxide which on oxidation gives the ethyl
methyl ketone having a somewhat higher boiling point than acetone. vBy using a secondary
metallic alkoxide which on oxidation gives a
volatile’ ketone, the formation of aldehydes by
oxidation of the alkoxide is obviated. The proc- '
ess is distinguished ‘from processes in which a
metallic ethoxide is used which on oxidation
gives acetaldehyde which enters the. ?eld of re
action and complicates it.
The present process is well adapted for use for
the production of high yields and large amounts
of the unsaturated alcohols.
10V
_
The invention is illustrated by the following
specific examples but it will be understood that 15
the invention is not limited thereto as other alde
hydes may be reduced in a similar manner and
other aluminum alkoxides may be used. In the
following examples the parts given are by weight.
Example 1.4mm alcohol from crown-aldehyde
Into a glass distilling vessel equipped with a
re?ux condenser connected to a water-icooled
downward distilling condenser is placed a solu
tion of 252 parts of pure crotch-aldehyde in 420
parts of benzene. To this is added 244.8 parts
of aluminum isopropoxide (corresponding to a
molecular ratio- of crotch-aldehyde to aluminum
isopropoxide of 3:1) in 280 parts of benzene.
The distilling vessel is gently warmed by a steam
jacket so that a slow distillation occurs, and the
30
heating is continued until about 180 parts of
distillate is collected over a period of e. g. 51/2 to
6 hours. This distillate is mainly acetone, al
though toward the end of the distillation it con
tains a considerable proportion of benzene. The
rate of heating is now increased, so that most of
the benzene comes off rapidly. The residue in
the ?ask is acidi?ed with an excess of 20% sul
furic acid, and extracted several times with ben
zene.
The combined benzene extractions are
Washed once with a little water, dried, and frac
tionated. The portion boiling at 115-125" C. is
collected as crude crotyl alcohol, and on refrac
aluminum alkoxides having the general formula
tionation yields crotyl alcohol boiling at 121-l22°. 45
A1(OR)3, in which R is an alkyl radical, and in
which the alkoxy group is a secondary alkoxy
group which will be oxidized to a ketone rather
Ecample 2.—Cr0tyl alcohol from crown-aldehyde
than an aldehyde
The simplest of such com
50 pounds is aluminum isopropoxide which is an
effective reducing agent for the unsaturated
aldehydes and which on oxidation gives acetone
which is readily volatile. Instead of aluminum
isopropoxide other secondary aluminum alkox
ides can‘ be used, for example, aluminum second
47 parts of aluminum turnings or wire are
placed in a still with 400 parts of commercial
98% isopropyl alcohol and 2.5 parts of mercuric
chloride. The mixture is re?uxed until all of
the aluminum has reacted, after which 210 parts
of crotch-aldehyde and 480-560 parts of isopropyl
alcohol are added and the heating and re?ux
ing is continued, with slow distillation of the 55
2,098,206
acetone formed. The mixture is slowly distilled
being kept, at 60-70° C. by maintaining the tem
perature of the heating jacket at about 110° C’.
is added a solution of 244.8 parts of aluminum
isopropoxide (1 mole to 3 mols of the butyralde
hyde) in 240 parts of benzene. The reaction is
regulated as in Example 3, and the product iso
The re?ux column is then removed or discon
lated in a similar manner. Butyl alcohol, B. P.
nected, and the solvent is distilled off, using an
ei?cient condensing device to recover the sol
are obtained.
for e. g. 8-9 hours, the temperature of the vapors
vent, which may be used again. When the reac
tion mixture has cooled to 40° C. it is hydrolyzed
with 900 parts of 6N sulfuric acid, and allowed
to cool to room temperature. The acidi?ed mass
separates into two phases, an oil phase and an
aqueous phase, which are separated. The oil
phase is distilled at reduced pressure, the dis
15
116-118° C. and butyl butyrate, B. P. 163-166° C.
‘ Example 6.—C'rotyl alcohol from crown-aldehyde
The 244.8 parts of aluminum isopropoxide of 10
Example 1 are replaced by 295.2 parts of alu
minum secondary butoxide,
..
tilling temperature being maintained at 60
A1 O<—HC205
70° C. by slowly lowering the pressure from
275 mm. to 65 mm. When the distillation slows
down, the pressure is reduced to 20 mm. and
the temperature allowed to rise to 90-100° C.,
insuring removal of the last of the crotyl alcohol
without obtaining higher boiling polymerization
products.
The aqueous phase is also distilled, the dis
tillation being continued until it no longer gives
25 a positive response to a test for the presence of
unsaturated bodies.
This usually occurs when
the distillation temperature reaches 99-100” C.
The distillate is treated with potassium car
bonate, and combined with the crude alcohol
distillate from the oil phase. The resulting mix
ture is dried with potassium carbonate, and dis
tilled through a re?ux column. The portion
boiling between 117° C. and 122° C. is collected
and refractionated.
with an air cooled re?ux condenser connected to
a downward directing condenser. The mixture
is heated to the boiling point by means of a
steam jacket, and, when solution is nearly com
plete, 92.4 parts of citronellal (3 mols to 1 mole
of the isopropoxide) are added. Heating is con
tinued, and after a short time the mixture as
sumes a yellow color. The rate of heating is
so regulated that a slow distillation is main
tained, about 200 parts of distillate being col
50
lected over e. g. 31/2-4 hours. The mixture is
then allowed to cool, and is mixed with an ex
cess of 20% sulfuric acid, that is, su?‘icient acid
to dissolve the gelatinous precipitate which ?rst
forms. The upper organic layer is drawn o?,
washed twice with a solution of sodium car
bonate, and distilled. The fraction boiling at
55
222-224“ C. at atmospheric pressure is collected
as
citronellol.
-
'
Example 4.—C'mnamyl alcohol from cinnamic
aldehyde
60
25.9 parts of aluminum isopropoxide and 160
parts of benzene are placed in a still similar to
that described in Example 3. The mixture is
heated to the boiling point, and when solution
is nearly complete, 50 parts of cinnamic alde
65 hyde (3 mols to 1 mole of the isopropoxide) are
added.
The conditions are regulated as de
scribed in Example 3, and the product isolated
in a similar manner. The product, boiling at
135-142" C. at 7 mm. pressure, is the cinnamyl
70
alcohol.
3
and the reaction carried out as in Example 1,
except that the methyl ethyl ketone formed, is
distilled over at a somewhat higher temperature.
Other aluminum secondary alkoxides, prepared
from aluminum and a secondary alcohol, may be
used in a similar manner, and other solvents may
be used. Also other aldehydes, both saturated
and unsaturated, can be similarly reduced to the
corresponding alcohols.
We claim:
1. The process of reducing aldehydes to the
corresponding alcohols which comprises subject
ing said aldehydes to the action of a secondary
alkoxide of aluminum.
2. The process of reducing aldehydes to the
corresponding alcohols which comprises subject
ing said aldehydes to the action of aluminum iso
propoxide.
' Example 3.—C'itronellol from citronellal
40.8 parts of aluminum isopropoxide and about
270 parts of benzene are placed in a still equipped
40
OH:
'
Example 5.—Butyl alcohol from butyraldehyde
259 parts of freshly distilled butyraldehyde
and ‘400 parts of benzene are placed in a still
similar to that described in Example '3. To this
3. The process of'reducing unsaturated alde
hydes to the corresponding unsaturated alcohols
which comprises subjecting said unsaturated al
dehydes to the action of a secondary alkoxide of
aluminum.
40
4. The process of reducing unsaturated alde
hydes to the corresponding unsaturated alcohols
which comprises subjecting said unsaturated alde
hydes to the action of aluminum isopropoxide.
5. The process of reducing croton-aldehyde to
the crotyl alcohol which comprises subjecting said
croton-aldehyde to the action of a secondary
aluminum alkoxide.
6. The processrof reducing croton-aldehyde to
the crotyl alcohol which comprises subjecting said
croton-aldehyde to the action of aluminum iso
propoxide.
'7. The process of reducing cinnamic aldehyde
to the cinnamyl alcohol which comprises subject
ing said cinnamic aldehyde to the action of a
secondary aluminum alkoxide.
8. The process of reducing cinnamic aldehyde
to the cinnamyl alcohol which comprises sub
jecting said cinnamic aldehyde to the action of
aluminum isopropoxide.
9. The process of reducing citronellal to cit
ronellol which comprises subjecting said cit
ronellol to the action of a secondary aluminum
alkoxide.
10. The process of reducing citronellal to cit
ronellol which comprises subjecting said cit
ronellol to- the action of aluminum isopropoxide.
11. The process of reducing aldehydes to cor
responding alcohols which comprises subjecting
such aldehydes to the action of an aluminum 70
alkoxide which on oxidation yields a readily
volatile alkyl ketone.
WALTER H. HARTUNG.
WILLIAM G. YOUNG.
FRANK S. CROSSLEY.
,
Patent No. 2,098,206‘\
CERTIFICATE OF CORRECTION.‘
of the above numbered patent zl'equiring correction as follower Page 2_, vsecond
column, line 17, in the formula, for "0205" read C2H5; and-‘that the'said
Letters Patent should be read with this correction therein that-the same
may 'cohi‘onn to the recorj'd of the case- in the Patent Office.
'
sighed and sealed this 25th day of January, A. -D. ‘1958.
Henry Van'Arsdele';
(Seal)
_
Acting Cemmis'sioner of Patents»;
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