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"Patentedxjan’. 7,1947
; vf 3
‘ '
2,413,889
_ 3g" "PRODUCTION
2,413,889
or ACRYLIC acn)
a . V
’
_
I
" Chess'ie E. Itehberg, Glenside', snatched” n.‘ a
,Fisher, Abinz'ton, Pm, assignorsmtoeUnlted .
States of-America as represented by‘ the Score-1 , ‘
,
‘.L'tary ‘of Agriculture
.} No Drawing; Application November ‘11, 1944,
_
:
‘SerialNo. 563,047
scalar.
‘ , (Granted
-
(01, 260——526)_
>
"
i
‘
_
‘a
_
,
under the act ‘cf-March 3,1883, as ‘f
‘amended April 30, 1928: 370 0. G. 757) ‘
This application
made ‘,under the ‘act "of
product, methyl Iormate, was then slowly with;
March 3,, 1883, as amended by the, act of,April
drawn as formed until its production ceased (8
to 10 hours). The excess methyl acrylate was
30, 1928, andthe. invention herein described, if '
' patented, may, be manufactured and used by or
' then distilled at a pressure of 140 mm., after
for theGovernme'nt -oi' the United States oi
America for governmental purposes without the
payment to us of any royalty thereon.
‘
which the formed acrylic acid was distilled at
56° ‘C. (25 mm.). The yield was 231 g. (80 per
‘
1 cent of the theoretical based on the formic acid
used). Over 91 percent 01' the methyl acrylate
saturated acids by‘the acidolysis ofv unsaturated
put into the reaction mixture was either recov
esters, and particularly to the~production of 10 ered or converted into acrylic acid.
acrylic acid by the reaction of an ester of acrylic
When acetic acid and unsubstituted methyl
This invention relates to the production of un-w
acid with, an organicacid other thanthe acid
to‘be formed, in particular, with a saturated ali
acrylate were reacted in a similar manner, acrylic '
‘
phatic acid such as formic acid or acetic acid.
acid was obtained, although
the rate of acid-
olysis was slower.
;
Y
The preparation of dry acrylic acid in high 415 The process is not limited to the speci?c re
yields in accordance with the‘ present ‘known
agents and conditions given above. Other ‘min
methods is di?icultt Hydrolysis of methyl acry
eral acid catalysts maybe used instead of the
late or ethyl acrylate yields various side products
sulfuric acid, and various polymerization inhib
in addition to the desired acrylic acid, and the
itors may be substituted for the hydroquinone.
acrylic acid produced is contaminated with war-y 20 Entraining
agents may be used to facilitate the
distillation oi’ the various fractions. Various
This invention has among its vobjects the prep-,
other. acids, such as butyric acid, benzoic acid,
aration of dry acrylic'acid' under essentially an‘
boric acid, and lactic acid may be used instead
, hydrous conditions in high yields by acidolysis
of the formic acid or the acetic acid, and other
of esters of acrylic acid with anhydrous organic 25 esters of acrylic acid, particularly alkyl acrylates,
acid other than the acrylicv acids prepared; and
may be used in place of the ,methy1 acrylate.
such other objects as willlbe apparent from the
Also, other estersv of higher series may be used,
following description and claims.‘v
.
.
3
such as esters of crotonic acid, to produce cro
In accordance with the invention, dry acrylic
tonic acid, although preferably, for purposes of
ter.
‘
I
,
,
,
_.
acid is preferably produced by reacting by mix,
ing and heating a suitable ester of acrylic acid
30 fractional distillation, the reacting acids and es- .
ters should be so selected that the produced by
product ester boils at the lowest boiling point,
with an anhydrous saturated aliphatic acid in
‘ , the presence of a mineral acid esteriflcation cat
alyst and a polymerization'_ inhibitor, and'remov
ing the by-product ester, which is produced by
replacement of the hydrogen oftthe carboxylic
group of the saturated aliphatic acid employed
with the acrylic ester group, as the by-product
' the excess reacting ester boils next, and the
,iormed unsaturated acid boils at the highest
35
point.
'
,
.
Either continuous or batch operation may be
used, but'it is preferred that the formed by
product ester be removed continuously in the
"ester is formed. For example, when methyl
manner indicated.
,
'
acrylate and anhydrous formic acid are reacted,
the by-product, methylformate, is distilled until 40 Having thus described the invention, what is
the reaction'is complete, and‘the‘formed acrylic
acid'isthen recti?ed._
"
‘g
,
‘
,
,
'
>
The process is exhibited by the following ex
ample:
.
'
r
7
Four moles (184
"
"*‘
Example
g.)’ of formic ‘acid,’ 12’ moles‘
(1032 g.) of unsubstituted methyl‘ acrylate (an"
excess of the-amount required for the reaction),
claimed-is:
‘
1. A process of preparing dry acrylic acid com
" prising mixing and heating an ester of acrylic
acid with a saturated aliphatic acid under an
hydrous conditions in the presence of a mineral
- acid ,esteriilcation catalyst and a. polymerization
inhibitor, and removing‘ the by-product ester
which is produced as it is formed.
2.‘ A process of preparing dry acrylic acid com
30 g. ‘of hydroquinone as a-polymerization 'in
prising mixing and heating an alkyl acrylate
hibitor, and‘2 ml. of sulfuric acid‘ as a‘catalyst
with a saturated aliphatic acid under anhydrous
were mixed‘ and re?uxed in a still having a 3
conditions in the presence of a mineral acid es
i’oot column and a; variable take-off head; ‘The - terification catalyst, and a polymerization inhib
, still was operated wlth‘total reflux until the tem-'
itor, and removing the lay-product ester which
perature at the still-head fell to 32° C. The by 55 is produced as it is formed.
.
9,418,889 '
4 .
3 .
8. A process otjpreparing-dry acrylic acid c0m-~
erltlv acid esteriiication catalyst and a polymeri-I
prising mixlng'and heatingmethylacrylate with
‘ zation inhibitor, removing'the by-product ester
a'saturated aliphaticacid under'anhydrous oon-,
, which is produced‘as- it is formed, and then frac
tionally distilling the reaction mass to separate
theexcess alkyl acrylate from the formed acrylic
ditions in the presence; or a- mineral lacid es
teri?cation catalyst and a polymerisation inhib.
itor. and removing the try-product ester which’ is
produced as it is tor-med;
6. A process of preparing dry acrylic acid com
‘
prising mixing and heating an excess of methyl
acrylate with formic acid under anhydrous con
formic acid under anhydrous conditions in the‘ 10 tions in the presence of a mineral acid esteri?
cation catalyst and a polymerization inhibitor,
presence of a mineral acidv esteri?cation catalyst
4. A process 01' preparing dryacrylic acidicom- ’
prising mixing and'heating-methylacrylate with '
and a polymerization-inhibitor. and removing- the
by-product, methyl tormateras it is formed.
5. A process of preparing dry acrylic acidcom
prising mixing and heating an excess of an al
kyl acrylate having a lower boilingpoint than
acrylic acid with a saturated aliphatic acid under
anhydrous conditions in the presence of} min- _
removing the by-product, methyl tormate, as it
is formed, and then fractlonally distilling the
reaction mass to separate the excess methyl acry
15 late from the formed acrylic acid.
CHESSIE E. REHBERG.
CHARLES H. FISHER.
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