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Патент USA US2072806

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Patented Mar. 2, 1937
2,072,806
’ _' UNITED STATES PATENT ‘OFFICE
2,072,806
PROCESS FOR THE SEPARATION O15‘v PRI
MARY FROM SECONDARY ALCOHOLS
Dennistoun Wood, Jr., Palo Alto, Calif., assignor
to E. I. du Pont de Nemours & Company, Wil
mington, Del., a corporation of Delaware
No Drawing. ApplicationJanuary 6, 1933,
Serial No. 650,508
4 Claims.
This invention relates to a process for the
separation of primary from secondary alcohols
contained in a mixture thereof and particularly
to the separation of such alcohols contained in a
5 mixture of oxygenated organic compounds ob
tained by the catalytic hydrogenation of carbon
oxides under pressure.
The orthodox method for separating primary
from secondary alcohols involves, generally,
10 heating the mixture of alcohols in a benzene so
lution with phthalic anhydride. The primary al
cohols react with phthalic anhydride to form the
esters more readily than do the secondary alco
hols and usually the half-ester is produced. The
'
'
(0]. 260—1576)
thermal treatment, the anhydride and the pri
mary alcohol. Other objects and advantages will‘
hereinafter appear.
.
I have found that ‘primary alcohols can be
separated from secondary alcohols by treating a 5
mixture of them with phthalic anhydride in ac
cord with the present invention without the
many di?iculties inherent in the above method
of separation. Furthermore, I have found that
in lieu of using phthalic anhydride a number of 10
other anhydrides may be employed for eiiect
ing the separation providing these anhydrides
from esters with the primary alcohols which have
boiling points greater than the boiling points of
15' resulting benzene solution is then cooled to crys ' the mixture of alcohols being treated and furtallize out the phthalic anhydride which has not ther providing they can be reconverted upon
reacted, and is subsequently treated with just thermal decomposition into the anhydride.
Generally speaking, my process may be car
enough alkali to change the monophthalate of
the primary alcohol to an alkali monoalkyl ried out in the following manner, for the separa
20 phthalate.
By means of this alkali treatment tion of a mixture of alcohols containing both
the alkali monoalkyl phthalate containing the 'the primary and secondary alcohols. The mix
primary alcohols separate in the lower layer ture is heated with the anhydride until solution
is complete and the resulting solution is then're
from the benzene containing the unreacted sec
ondary alcohols which collect in the upper lay
?uxed at a temperature somewhat ,below the
25 er. The layers are separated and washed-the boiling point, until all of the alcohols present,
alkali layer with benzene and the benzene layer which will react with the anhydride, have react
with water. A fair degree of separation of the ed. The temperature is then raised, whereupon
the unreacted alcohols will distill over leaving
alcohols may be obtained The separated alka
line portion is then further treated with excess behind the half-ester formed between the pri
30 alkali to give the di-alkali phthalate, and the mary alcohols and the anhydride. In order not
to decompose the half-ester the temperature of
primary alcohols, which are released by this re
this preliminary distillation should be as low
action, may then be removed by steam distilla
tion. The secondary alcohols are separated by as possible, and it is, therefore, of advantage to
distillation from the benzene layer. By this conduct it under a fairly high vacuum,—say,
from 1 to 50 mm. of mercury. The remaining
35 treatment, of course, there remains as a by
product the di-alkali salt of phthalic acid which half-ester is further heated usually under pres
cannot again be used in the process until it has sure, whereupon it \will be decomposed, the pri
been reconverted to the anhydride.
mary alcohols distilling over leaving behind'as
a residue the anhydride.
An object of the present invention is to pro
40 vide a process for the separation of primary
When effecting the separation of primary from
from secondary alcohols having many outstand
secondary‘ alcohols present in a mixture of oxy
genated organic compounds obtained by the
ing advantages over the orthodox method de
scribed above. A further object of the invention catalytic hydrogenation of carbon oxides under
is to provide such a process for the separation pressure, (these compounds may be made ac
45 of the primary from the secondary alcohols cording to any of the known processes therefor,
found in the mixture of oxygenated organic com
e. g. those described in U. S. Patents Nos. 1,820,
pounds obtained by the catalytic hydrogenation 417 and 1,844,857), or other mixtures contain
ing primary and secondary alcohols, there may
of; carbon oxides under pressure. A still fur
thér object of the invention is to provide a proc
be present in these mixtures a number of un
known organic substances which are separated
50 ess for the separation of primary from second
ary alcohols by the aid of an anhydride which with the primary or secondary alcohols portions.
forms an ester with the primary alcohols having Hereinafter, therefore, when referring to the sub
a boiling point higher than the ‘boiling point of stances separated by my process from such mix
the unreacted secondary alcohols present and tures, in order to include all of those contained
55 which can be readily decomposed to give, by in the portion removed by esteri?cation from the
15
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30
v35
40
45
50
55
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aoveicoa
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portion left unesteri?ed, the portions will be -ment, to e?ect a separation of the alcohols from
designated as the esteri?ed and unesterified por
a fresh mixture thereof. ,
tions respectively, the former including the pri
In order to increase the “rapidity of
v the es- "
mary and reactive ‘alcohols, the-latter the sec
teri?cation stage suitable catalysts may be pre
ondary and nonereactive alcohols.
" sent, such, for example, as sodium‘ or lead oxide,
When separating the primary from the sec
ondary alcohols, or ester-forming from non-‘ester
forming compounds present in a mixture of oxy
although their presence is by no means essential
to the operation of the’ process.
The temperature used for eifecting the es
genated organic ‘compounds obtained by the
teri?cation as well as that used to distill over the
10 catalytic hydrogenation of carbon oxides under
unes'teri?ed compounds and ?nally that employed
pressure, I prefer generally to use phthalic an
for decomposing ‘the anhydride will, ' of course
hydride, although for the separation’of' the al
be determined by the mixture of compounds be
cohols present in this mixture, as well as for the ing separated as well as the anhydride being,
separation of similar alcohols from any other’ utilized to e?’ect the separation. ‘Ordinarily it
15 mixture containing them, the anhydrides of the
has been found advantageous to use a fairly 15
following acids may be employed: adipic, suc
high vacuum when e?’ecting by distillation the
cinic, sebacic, tartaric, trimesic, hexahydro
separation of the unesteri?ed from the esteri?ed
phthalic, tetrahydrophthalic; and in many in
compounds,_ and when decomposing the half-es
stances the anhydride of thehmonobasic acids ter of'thev anhydride, pressure is often of ad
may be used, such, for example, as propionic, vantage to facilitate rapid and thorough decom 20
butyric, isobutyric, etc.
'
position.
\
I will now give an example to illustrate more‘
speci?cally one method by which my process
From a consideration of the above specification
it will be realized that any process for the sep
may be carried out, but it will be understood that aration of primary from secondary alcohols or
25 I shall not be restricted by the details therein
the esteri?able from the non-esteri?able por 25
given except as they, may be limited in the» ap
tions of a mixture of oxygenated organic com
pended claims.
7
pounds will come within the scope of this inven
' EmampZe.—-96,300 cubic centimeters of the tion, if such a separation is e?'ected by the proc
oxygenated organic compounds, obtained by the
catalytic hydrogenation of carbon oxides'under
ess hereinbefore described.
pressure, boiling between approximately 133~147° '
1. In a process for the separation of easily
esteri?able'portions from the more di?icultly es
teri?able portions of a mixture of oxygenated
0., and which contain approximately 54% pri
mary and 40% secondary alcohols including such
alcohols as 2,4-dimethyl pentanol-3, 3-methy1
35 pentanol-2, 2-methyl pentanol-l, etc., the re
I claim:
Y
.
.
30
organic compounds obtained by the catalytic hy
drogenation of carbon oxides under elevated tem 35
maining 6% comprising ketones and other com
perature and pressure the steps which comprise
pounds, were mixed with 190 lbs. of ?aked - esterifying the easily esterifiable portion of the
phthalic anhydride. The mixture was heated mixture of compounds with an organic dibasic
to e?ect solution of the anhydride in the mix
acid anhydride which forms'therewith an ester,
40 ture of compounds and then re?uxed at a tem
the boiling point of which is higher than the boil
perature of approximately 100° C. and one at
mosphere of pressure in order to convert the pri
mary alcohols present into the half-ester of
ing point of the unesteri?ed portion of the mix- '
phthalic acid. After approximately 12 hours, the
by thermal decomposition splitting up the ester,
thereby reforming the anhydride and the ester
45 esteri?cation was considered to be complete and
the temperature of the mixture was then raised
and the pressure lowered to approximately 5 cm.
of mercury and between the temperatures of
110-140° ‘C. 75,200 0. c. distilled over, constitut
ing approximately all of the unesteri?ed com
pounds present in the mixture of compounds
and containing substantially all of the secondary
alcohols.
The temperature of the mixture was
further raised and between 140_-160° 0., which
ture of compounds, separating by distillation the
resulting ester from the unesteri?ed portion and
ifled portion.
1
-
2. In a processfor the separation of easily
esteri?ableportion’from the more di?icultly ester
i?able portion of a mixture of oxygenated or
ganic compounds obtained by the catalytic hy
drogenation of carbon oxides under elevated
temperature and pressure, the steps which com
prise esterifying the easily esteri?able portion of
the mixture of compounds with phthalic anhy
55 may be designated as the transition stage, the
dride, separating by distillation the resulting
last of the unesteri?ed compounds distilled over
along with some of the products resulting from
the decomposition of the .phthalic ester. The
pressure was then vraised to-approximately one
atmosphere and from 160° C. up 25,000 0. c. of
phthalate from the more di?lcultly esteri?able
the phthalate decomposed releasing primary al
cohols and esteri?ed compounds which distilled
' over, leaving as a residue phthalic anhydride.
The primary and secondary alcohols obtained in
65 accord with this process can then be separated
by fractional distillation or by other suitable
methods into the individual alcohols.
The advantages derived from utilizing my
process are apparent when it is realized that all
of the laborious extraction and washing opera
tions present in the former orthodox method have
been eliminated, and, furthermore, the anhydride
obtained upon the thermal decomposition ,of the
75 half-ester is ready for use, without further treat
portion and’ by thermal decompositionreforming
the esteri?ed portion from the reconverted
phthalic anhydride.
'
3. In a process for the ‘separation of the pri
mary alcohols from the secondary alcohols pres
ent in a mixture of-oxygenated organic com
pounds obtained by the catalytic hydrogenation
of carbon oxides under elevated temperature and '
pressure, the steps which comprise esterifying
the primary alcohols of the mixture of compounds
with an organic dibasic acid anhydride which
forms therewith an ester, the boiling point of
which is higher than the boiling point of the sec
ondary alcohols present in the mixture of com
pounds, .separating by distillation the resulting
ester from the secondary alcohols and by thermal
decomposition splitting up the ester, thereby re
forming the dibasic acid anhydride and the pri
mary alcohols.
1
50
2,072,806
4. In a process for the separation of the primary
alcohol portion from the secondary alcohol por
tion of _a mixture of oxygenated organic com
pounds boiling between 133 and ‘147° C., and ob
tained by the catalytic hydrogenation of carbon
oxides under elevated temperature and pressure,
the steps which comprise reacting 96.3 liters of
the- oxygenated organic compound with approxi
mately 190 pounds of ?ake phthalic anhydride,‘
10 heating the resulting mixture to 100° C., and re
3
?uxing for approximately 12 hours, distilling the
resulting product under a vacuum oi.’ approxi
mately 5 centimeters of mercury and at a tem
perature of from 110 to 140° ‘0., to remove the
secondary alcohols and the unesteri?ed products,
raising the pressure to approximately 1 atmos
phere and the temperature to from approximately
160° 0., up and distilling of! the primary alcohols
by decomposition of the phthalates.
DENNISTOUN WOOD, JR.
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