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Патент USA US2110830

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Patented Mar.‘ 8,‘ 1938
2,110,330 j
1 UNITED ‘STATES
PATENT ‘OFFICE
2,110,830
SIMIULTANEOUS PRODUCTION OF VINYL
AROMATIC OOMPDUNDS AND ARYLACET
YLENES
Robert a. Dreisbach, Midland, Mich” assignm
to The Dow Chemical Company, Midland,
_ Mich, a corporation of Michiga
No Drawing.v Application October 6, 1937,
,
,
Serial No. 167,598
'
.
5 Claims. ,(01. 2604-168)
This invention concerns the simultaneous pro passing isopropyl benzene alone or in admixture
duction of a vinyl‘ aromatic compound and an
arylacetylene by pyrolysis of a benzene deriva
tive having the general formula
6,
_
‘-
‘
with a gaseous diluent such as steam‘ or carbon
dioxide through an externally heated tube or a
bath of-lead or other molten metal, but care
must‘ be taken‘ to heat and promptly cool the‘ 5
vapors with suiilcient rapidity to avoid excessive
X5
carbonizatlon. _In practice the pyrolysisv is pref
Y.’
erably carried out according to the general meth
_
wherein R. represents an isopropyl or isopropenyl
od for pyrolyzing alkylated aromatic hydrocar
0 radical, X and Y each represent hydrogen, halo-. bons set forth in my co-pending application, 10
gen, or an alkyl radical containing not ‘more ‘ Serial No. 151,457, ?led .July 1, 1937, of which
than 3 carbon atoms, and n and n’ are integers this application is a continuation-in-part. This
having a sum not exceeding 5. The invention ‘preferred mode ofmpperation, described below,
particularly concerns the simultaneousiproduc
permits the desired ‘products to be formed inv ,
15 tion of styrene and phenylacetylene‘by pyrolysis higher yield than I have found possible vby the 15.
of one or both of the compounds isopropyl ben
usual pyrolytic methods,v without appreciable.
zene and alpha-methyl styrene.
‘
‘
Isopropyl benzene has heretofore been pyro
lyzed at temperatures up to, but not exceeding
90 700° 0., to obtain styrene‘ and alpha-methyl
styrene, but phenylacetylene has not been re
ported as a product of the reaction. In my own
researches I have never obtained more than
faint traces of phenylacetylene by pyrolyzing
25 isopropyl benzene at such temperatures.
carbonizatlon or tarring of the reaction mix
ture.
,
In my preferredmode of operation, liquid or @
vaporized isopropyl benzene and superheated 20
steam are passed continuously into admixture
with one another, the steam being employed in
the proportion'and at the temperature required
to attain the reaction temperature and furnish
the heat of pyrolysis. Usually, between 7 and 10 25
parts by weight of steam superheated to a tem
However, I ‘have found that isopropyl benzene
may satisfactorily be pyrolyzed at higher tem . perature between_800° and 1000° ‘C. is used‘ per
peratures to obtain not only the usual products, part of isopropyl benzene, but the steam may of
‘styrene and alpha-methyl styrene, but also course be employed in other proportions and at
. _ 30 phenylacetylene in appreciable yield. In general,
even higher temperatures. The pyrolysis‘ mix- 30
the yield of phenylacetylene becomes higher and ture is promptly cooled; e. g. by ‘contact with ‘
, that of alpha~methyl styrene lower as the pyrol
water or passage through suitable heat exchang- ‘
ysis temperature is raised and by the use of tem
peratures above 900° C. the formation ‘of alpha
ers or condensers, to a temperature below that
at which rapid pyrolysis occurs, e. g. below 700°
35 methyl styrene may practically be eliminated. . I 1 0., and the cooling is continued to condense the 35
have also found that the styrene and phenylacet- ~ aromatic components of- the mixture. The or
ylene, which boil together,'may readily be sep
ganic condensate is then distilled to collect. as ’
arated by distillation‘ from any alpha-methyl
styrene and unreacted isopr‘opyl benzene present
one fraction a mixture ‘of styrene and phenylacet
ylene and as other fractions alpha-methyl ‘sty
40 and that‘the alpha-methyl styrene, alone or ad
rene (when formed) and any unreacted isopropyl 40
.mixed with isopropyl benzene, may be further‘ benzene. The alpha-methyl styrene may be col
pyrolyzed‘ to produce additional styrene and lected as a ?nal product or it may be returned‘,
phenylacetylene. The phenylacetylene serves as alone or in admixture with isopropyl benzene.
an eifective’agent for preventing polymerization to the pyrolysis for the formation of additional
45 of the styrene‘, hence the mixture of these two
‘ compounds is a valuable and marketable prod- '
50
styrene and. phenylacetylene.-
»
~
45
~ As hereinbefore indicated, the phenylacetylene
not. When desired, the phenylacetylene may be
separated from the styrene by the chemical treat
formed in the reaction distills together with the
ments hereinafter described.
ter during manufacture, distillation, storage, and
shipment. Accordingly, this mixture of styrene‘ 50
'
I
In. order to obtain phenylacetylene in appre
ciable yield, the pyrolysis is conducted at tem
peratures above 750° C. and below that at which
excessive carbonizatlon occurs, preferably be
‘ tween 800° and ‘950° C. The pyrolysis may be
55 carried out in any of the usual ways, e.‘ g. by
styrene and inhibits polymerization of the lat
and phenylacetylenev is a valuable product having 1
properties not possessed by styrene alone. When
desired, part or all of the phenylacetylene may be
removed from the ' styrene eithem-(l‘), by agi-'
tating the mixture at ‘room temperature or there- 55
2,1 10,880
(2.,
about with a mixture of mercuric oxide and a
actor suf?'ciently to condense the aromatic prod- "
30-50 per cent concentrated aqueous sulphuric
acid solution to convert the phenylacetylene into
lower aliphatic hydrocarbons. The organic layer
ucts, leaving a gaseous mixture of hydrogen and
of the condensate was separated and dried. It
consisted of 18.7 pounds of a mixture containing
approximately 43 per cent by weight of styrene, 16
other compounds, readily separable from styrene
by distillation, or (2) by treating the mixture
of styrene and phenylacetylene with an aqueous.
per cent of alpha-methyl styrene, and 4.3 per‘ cent
ammoniacal solution of a salt of a metal belong
ing to group. 1, family 2, 'of the periodic system, of phenylacetylene, the remainder being largely
e. g. silver chloride, silver sulphate, cuprous chlo unreacted isopropyl benzene and some benzene.
10
Example 3
10 ride, cuprous sulphate, etc., to precipitate the
phenylacetylene as its metal salt, e. g. as silver
64.5 pounds of isopropyl benzene was gradually
or . cuprous phenylacetylide. The ammoniacal
vaporized and the vapors were passed continu
‘metal salt employed in this treatment is pref
erably one containing the metal in its lowest ously into admixture with a , stream of steam 15
superheated to 890°, C., the respective rates of
15
?ow being such that the mixture had atempera
The ?rst of said methods for removing phenyl
acetylene is simple-and practicable, ‘but does not ture of about 825° C. The time of passage'was 3
permit recovery of the phenylacetylene as such. hours 30 minutes. The mixture was immediately
After said treatment the styrene is separated and cooled and condensed and the organic layer 0! the 20
20 puri?ed by permitting the treated mixture to condensate was separated and dried as in Example
stand and stratify, separating the organic layer 2. There was obtained 48.8 pounds of a’ liquid
thereof, washing this layer free of acid with water organic mixture containing approximately 52.8
or dilute aqueous alkali ‘solution, and distilling per cent by weight of styrene, 9.3 per cent of
alpha-methyl styrene, 8.5 per cent of phenyl
the same, e. g. with steam or under vacuum. .
The ‘second. of the above-mentioned methods acetylene, and 12.5 per cent of unreacted isopropyl
26
for removing the phenylacetylene does permit benzene, the remainder being largely benzene and
recovery of the latter. After precipitating the ethylbenzene. The yields of styrene, alpha
phenylacetylene as its metal salt, the latter isv methyl styrene, and phenylacetylene were 52.6
per cent, 7 .9 per cent, and 8.1 per cent, respective
- separated by ?ltration or decantation to recover
30 the liquid styrene. 'The precipitate may then be ly, based on the isopropyl benzene consumed in
valence.
_
-
acidi?ed with a strong mineral acid, e. g. an
the reaction.
aqueous sulphuric or hydrochloric acid solution,
to regenerate the phenylacetylene. The latter
Isopropyl benzene was vaporized and preheated
forms a distinct layer and may be separated me
to a temperature of about 440° C. and the pre
chanically from the acid and puri?ed by washing
with water. The invention, accordingly, permits
production of styrene and phenylacetylene either
in admixture or as the individual compounds.
The following examples illustrate certain ways
40 in which the principle or the‘invention has been
applied, but are not to be construed as limitin I
the invention.
-
Example 4 ’
Example 1
Isopropylbenzene was passed, in continuous
45 ?ow at a rate of approximately 50 grams per
36
heated vapor was passed continuously into ad
mixture with a stream of steam superheated'to
about 1070° C. at such rate‘that the temperature
of the resultant mixture was approximately 900°
C. The mixture was cooled and condensed im 40
mediately after ~formation and the organic layer
_ of condensate was separated, dried, and analyzed.
It contained 53 per cent by weight of styrene, 2
per cent of alpha-methyl styrene, and 8.3 perv
cent of phenylacetylene, the remainder being un
reacted isopropyl benzene and by-products such
minute, ?rst through a heated chamber wherein. . as benzene and probably naphthalene.
it was vaporized and preheated to about 285° C.
Example 5
and thence into admixture with a current of
steam superheated to approximately 825° C., the
50 [rate of‘steam ?ow being such that the mixture
formed had a temperature of approximately 750° '
Meta-chloro-isopropyl benzene was pyrolyzed
at 820° C. by procedure similar to that in Exam
me 3. The liquid organic product contained ap
C. The vapor mixture was passed in less than
proximately 39 per cent by weight oi.’ meta
~ 0.03 second through the mixing zone directly‘
chloro-styrene, 5.1 per cent of meta-chloro-phen
into condensers wherein it was rapidly cooled and
ylacetylene, 3.9 percent or meta-chloro-alpha
55 - condensed. The organic layer of the condensate
methylstyrene, and 3.5 per cent of styrene, the
was separated and dried.’ It‘ contained approxi
mately 45.4 per cent by weight of unreacted
isopropyl benzene, 27.3 per cent- of-styrene, 14.8
per cent of alpha-methyl styrene, and 0.43 per
60
remainder being largely unreacted meta-chloro
cent 01' phenylacetylene.
’
‘
Example 2
isopropyl benzene and some by_-products such as
vchlorobenzene and meta-chloro-ethylbenzene.
I have also pyrolyzed meta-ethyl-isopropyl
benzene as hereinbeiore described to obtain a
product comprising styrene homologues, e. g.
meta-ethyl styrene, meta-divinyl benzene, etc.,
and arylacetylenes, e. g.-phenylacety1ene, meta
vinyl-phenylacetyle'ne, etc. The arylacetylenes
benzene vapors and approximately 205 pounds of . in the mixture inhibited polymerization of the
highly superheated steam were passed in steady I styrene homologues. Other nuclear substituted
‘ ?ow through a tubular iron reactor, wherein they isopropyl benzene compounds such as ortho-,
formed a mixture having a temperature of 805° , meta-,' or para-bromo-isopropyl benzene, 3-ch1o
Isopropyl benzene was vaporized and preheated
to about 220° C. 24,2 pounds of the isopropyl
ro-S-ethyl-isopropyl benzene, ortho-chloro-iso
70 C. The time of passage was 1 hour 20 minutes. . propyl benzene, para-methyl-isopropyl benzene,
The‘ ‘mixture passed through the reactor and into
’ suitable cooling apparatus at such rate as to be 'ldiethyl-isopropyl benzene, di-isopropyl benzene,
maintained at temperatures above ‘700° C. i'or'less
than 0.05 second, probably about 0.03 second.
75 The mixture was cooled asit issued from the re
‘
"lo
etc. may be pyrolyzed according to the inven
tion to obtain a product comprising homologues
or-analogues of'styrene and an arylacetylene. 75
3
2,110,880 '
In the claims the term “styrene-like compound"
radical, x and Y each represent hydrogen, halo
refers to a compound of the ‘class consisting of
gen, or an alkyl radical containing not more than
3 carbon atoms, and n and n’ are integers having,
a sum- not exceeding 3.
styrene and its homologues and analogues,
Other modes of applying’ the principle of the
._ invention may be employed instead of those ex
_
3; A method for the-simultaneous production
plained, change being made as regards the meth- , of a styrene-like compound and an arylacetylene
0d herein disclosed, provided‘the step. or‘ steps
which comprises simultaneously passing separate
stated by any of the following claims or the equiv
streams of superheated steam and of a benzene
alent of such stated step or steps be employed. derivative having the general formula ‘
10
I therefore particularly point out and distinctly _
i
10'
.claim as my inyention:-.—
‘
'.
'
1, A method for the simultaneous formation of '
_a styrene-like compound and an arylacetylene
which comprises pyrolyzing at a temperature o!v
_'
,
50“
Y.’
‘
,
15 at least 750° C. a benzene derivative having the wherein R represents an isopropyl or isopropenyl 15
‘ radical, X and Y each represent hydrogen, halo
general
formula
I
4
,
gen or an alkyl radical containing not more than
3 carbon atoms, and n and n’lare integers having
a sum not exceeding 5, into, admixture to form
Y,’
_
a mixture having a temperature between 800°
wherein R represents an isopropyl or isopro'pe
and 900° C. and promptly cooling the mixture 20,
nyl radical, X and Y each represent hydrogen, to a temperature below I100" 0., the steam em
halogen, or an alkyl radical containing not more ployed being superheated sufficiently to attain
4
than 3 carbon atoms, and n and 1],’ are integers said pyrolysis temperature. I
a sum not exceeding 5.
r
4. Aimethod for the simultaneous formation of 25
2.5 having
v 2. A method for the simultaneous formation of styrene and phenylacetylene which comprises py
a styrene-like compound and an arylacetylene rolyzing isopropyl. benzene at a temperature of
which comprises heating to a pyrolyzing tem
at least 750° C.
'
'
.
'
perature of at least 750° C‘. and cooling su?‘l
5. A method for the simultaneous formation of
-
x»v
‘
g8 .R.
ciently rapidly to avoid appreciable carboniza
tion, a benzene derivative having the general
I
formula
‘
mixture with steam superheated su?iciently' so '
_
X‘
atyrene and phenylacetylene which comprises 30
continuously passing isopropyl benzene into ad
'
I
‘Y.’
wherein R represents an isoprop'yl or ‘iso'propenyl
that the mixture is formed at a pyrolyzing tem
perature between 800° and 950° C. and cooling the
.mixture to a temperature below ‘700° C., within
0.05 second after formation.
1*
‘
.
,
ROBERT R. DREISBACH.
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