REACTIONS OF KETENE
HUGH.J. HAGEMEYER, JR.
Tennessee Eastman Corporation, Kingsport, Tenn.
Ketene and carbonyl compounds can react to form either
enol acetates or p-lactones and products thereof, depending on the choice of catalyst and reaction conditions.
Enol acetates are formed by reaction of enolizable carbonyl compounds-that is, a carbonyl compound containing a t least one available hydrogen atom on a carbon
atom adjacent to the carbonyl group-with ketene in the
presence of acid esterification catalysts. Acetylsulfoacetic acid is a preferred enol acetylation catalyst and
temperatures in the range 50" to 90" C. are usually employed. Ketene and carbonyl compounds react to form
p-lactones and products thereof in the presence of suitable
condensation catalysts. The optimum conditions, catalysts, and catalyst concentrations vary for individual
carbonyl comqounds. The choice of the catalyst and
catalyst concentration should be such that maximum
rate of reaction is obtained with a minimum formation of
diketene. If 0-lactones or decarboxylation products
thereof are the desired compounds, the reaction should
be conducted a t low temperatures, 0' to 10" C., to minimize the linear polymerization of the p-lactone. Where
the unsaturated acid is the desired product, the reaction
is conducted a t 40" t o 60" C., to ensure the gradual formation of the linear polyester of the p-lactone, which is then
depolymerized by distillation.
HC-CH
H e b-CHO
6'
CeHsCHO
+(CeHJz C=C(CoHs)z
+ COa
CH-C(OH)CHs
+ CH2=C=O/EI2SOd
+
With the advent of the work of Degering ( 4 ) and Kung (IO)B
renewed interest has been taken in the utilization of ketene in the
synthesis of organic compounds.
I n the author's laboratories the condensation of ketene with
itself and with carbonyl *compounds-aldehydes, ketones, diketones, keto esters, aromatic aldehydes and ketones, and unsaturated aldehydes and ketones-has been investigated. Other
catalysts have also been found which are suitable for the condensation and in some instances they are superior to the FriedelCrafts type catalysts for the formation and isolation of p-lactones.
Aldehydes and a,p-unsaturated aldehydes and ketones were also
enol acetylated.
+ GO1
DIKETENE
The dimerization of ketene should be considered in a study of
the condensation of ketene with carbonyl groups. Of the three
structures commonly assigned to diketene, p-vinylacetolactone
has been chosen as representing the product of the condensation of
the carbon-to-carbon double bond of one ketene molecule with the
carbonyl group of a second ketene molecule to form a p-lactone.
+ CHZO/ZnCl%--+CH2CH2C=0
LOJ
+ CH&HO/ZnClZ
CaH6CHCHZC=O +
KOAC
-0.J
60" C.
CsHsCH=CHs
CHFC(CH~)OCOCH~
CHz=C=O
and
CHZ=C=.O
+ CHa=C=O
CHsCOCHa
More recently Kung (10)described the condensation of ketene,
CHz=C=O, with formaldehyde and acetaldehyde in the presence
of Friedel-Crafts type catalysts to form propionolactone and pbutyrolactone, respectively.
CH*=C==O
---t
0
Hurd used anhydrous potassium acetate as a catalyst and in
addition to the decarboxylation products he isolated furacrylic
acid and cinnamic acid which probably resulted from the depolymerization of linear polyesters of the corresponding p-lactones
upon distillation.
Staudinger in 1911 ( 1 6 ) reported diphenylacetylation of the
enol of acetophenone with diphenylketene. Vinyl diphenylacetate was also prepared by the reaction of diphenylketene with
acetaldehyde. The enol esters were identified by hydrolysis and
isolation of diphenylacetic acid. Gwynn and Degering ( 4 ) in
1942 discovered that enol acetylation with ketene was accomplished in good yields by using acid esterification catalysts. Acetone and ketene reacted in the presence of sulfuric acid catalyst to
form isopropenyl acetate.
ETENE, the inner anhydride of acetic acid,ismanufactured
by the pyrolysis of acetic acid and acetone. Commercially it is used principally in the production of acetic anhydride
and, to a lesser extent, diketene. The discovery and development of new catalysts for reactions with ketene have now led to
the manufacture of p-lactones and enol acetates from carbonyl
compounds and ketene. Staudinger (17)first described the formation of @-lactonesby condensing diphenylketene with quinone.
I n condensations with diphenyllietene, Staudinger used compounds containing highly active carbonyl groups such as dibenzyl
ketone, quinone, and benzophenone. The condensation reaction
was carried out in the absence of catalysts and required elevated
temperatures such that the decarboxylation products of the plactones rather than the p-lactones themselves were isolated-for
example, benzophenone and diphenylketene give tetraphenylethylene and carbon dioxide.
+ (CeHJ2 C=C=O
\/
KOAc
60°C.
CH-CH
K
(CeH5)aCO
H:-~~CHCH.C=O
L-OJ
H
$ CH2=C=O --+
+ CH,=C=O
50" C.
CHz=$Xf;C=O
f
No catalyst
-3 CH,CHCH-C=O
CHaCOCH=C=O
L-0-J
A similar condensation with ketene and furfural and ketene and
benzaldehyde was reported by Hurd in 1933 (6) in which the plactone decarboxylation products, a-vinylfuran and styrene, respectively, were isolated.
I
CHz=CCH&=O
LO-1
I1
CHaC=CHC=O
LO--]
I11
Although many investigators show a preference for either Pvinylacetolactone (11) or 0-crotonolactone (111) as representing
765
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
766
the structure of diketene, it is interesting t o note that diketene
does not form @-alkoxy compounds with alcohols which is characteristic of the 0-lactones.
Diketene ( 2 5 ) is manufactured in 90 to 95% yields simply by
passing ketene in through a dispersion plate in the bottom of a
tower (Figure 1, omit formaldehyde and catalyst feed lines) filled
with diketene and overflows continuously at the top of the tower.
The rate of addition is controlled so that the liquid overflowing at
the top of the tower is substantially free of dissolved ketene.
Temperature is the important factor in controlling the dimerization of ketene and at 40"to 50" C. a smooth rapid rate of dimerization is obtained. The diketene is fed continuously to a still at
reduced pressure, 30 mm., for final purification. Catalysts should
never be used in the production of diketene.
Commercially ketene is produced by the pyrolysis of acetic acid
at reduced pressure, 40 t o 100 mm. Where diketene is the desired
product it is prepared by inserting one or more scrubbers in series
in the reduced pressure system. Ketene is fed into the scrubber
(Figure 2, omit formaldehyde and catalyst feed lines) below the
packing support and scrubbed with diketene.
Referring to the diagram, 1 indicates a primary scrubber which
may be cooled with water or other cooling agent through the cooling coil, 2. T h e scrubber is packed with Raschig rings and ketene
is metered through rotameter, 7, and enters the scrubber through
the nozzle, 17, below a packing support. Diketene is circulated
by a pump, 16, from the reserve tank, 5, through a cooled line, 13.
The rate of flow of diketene through the scrubber is gaged by the
rotameter, 15. The off-gas is led out at 22 and passes through a
condenser, 9, and a liquid gas separator, 10, to the jet in the reduced pressure system, Where a high throughput is desired two
or more scrubbers are usually connected in series. A copper
scrubber 6 feet high and 8 inches in inside diameter packed with
0.5-inch Raschig rings was used to produce 3 to 4 pounds of diketene per hour in 97% yield. Diketene is cycled through the
scrubber at the rate of approximately 1 to 2 gallons per minute at
30" to 35' C. and is overflowed at 25 to the reduced pressure still.
0-Butyrolactone is produced by the hydrogenation of diLetene
with Raney nickel catalyst at 60 to 70' C. and 300 to 500 pounds
per square inch in the presence of an equal or larger volume of diluent. @-Butyrolactone, benzene, and other inert hydrocarbon
solvents are suitable as diluents. I n the absence of diluents the
hydrogenation cannot be controlled and the diketene decomposes
with violence.
CH2=CCH&=0
L-OJ
+ Hz
diluent CH3CHCH&=0
-01
Ni(R)
GO" to 70' C.
500 pounds per square inch
-+
On increasing the hydrogenation temperature to 120 O to 160 * C.
@-butyrolactoneundergoes hydrogenolysis to n-butyric acid.
CH,CHCHzC=O
LO-_I
+ HZ -+
Ni(R)
CH3CHzCHzCOOH
120Oto 150" C.
I n continuous hydrogenation diketene can be hydrogenated directly to butyric acid.
REACTIONS OF KETENE WITH ALDEHYDES A h D KETONES
Ketene and aliphatic aldehydes such as acetaldehyde, propionaldehyde, and butyraldehyde react in the absence of catalyst t o
form a,p-unsaturated ketones.
2CHz=C=0
+ RCHzCHO
RCH&H=CHCOCHj
+ COz
Actually the ketene dimerizes to diketene and as such reacts
with the aldehyde to form a 0-lactone which decarboxylates upon
heating to form the a,P-unsaturated methyl ketone (1).
CH,COCH=C=O
+ RCHnCHO +CH3COCH--C=O
Vol. 41, No. 4
then
CH,COC€I-C=O
' b
+RCHzCH=CHCOCH3
+ CO2
RCHz-CHJ17ith acetaldehyde the product is 3-pentene-2-one; with propionaldehyde 3-hexen-2-one; and with butyraldehyde 3-hepten2-one. The reaction is conducted by passing ketene into a solution of the aldehyde a t room temperature. Conversions t o unsaturated ketones average between 50 and 65%,
A similar condensation reaction is not observed with ketones.
Ketene and acet,onedo react, however, in the absence of a catalyst
a t elevated temperatures, to form small amounts of isopropenyl
acetate in addition to diketene.
CHz=C=O+CH,COCH,/BO
O
C. --+CHz=C(CHJ-OCOCHI
ENOL ACETYLATIONS
With catalysts such as sulfuric acid ( 5 ) ,p-toluencsulfonic acid,
and particularly with acetylsulfoacetic acid in concentrations of
0.01 to 0.1% and a t 40Oto 80" C., the corresponding enol acetates
are formed. Acetylsulfoacetic acid is prepared b y the reaction of
acetic anhydride with sulfuric acid: the acetic acid is distilled off
at reduced pressure ( 8 ) .
+ 2( CHsCO) ~ O + C H S C O ~ S O ~ . ~ I € ~ C Of2CHyCOOH
OH
+ CH3CHO/Hd304 +CHFCHOCOCH~
CHFC=O
CI€?=C=O + CHaCOCIla/I12304 --+ CH2=C(CH3)0COCHa
H2S04
In the case of the aldehydes, the a,@-unsaturatedkelones \yvliich
result froni the condensation of diketene with the aldehydes are
formed in increasing amounts as me ascend in the aldehyde series.
TABLE
I. ESOLXCXTYLATIOK
Enol Acetate
Conversion,
C.
%
72
21
$.P.,
Carbonyl Compound
Acetaldehyde
Propionaldehyde
Butyraldehydo
-4oetone
RIethyl ethyl ketone
99
128
96
45
18
118
31
7
Unsaturated
Ketone,
Conversion,
%
17
34
51
None
None
The conversions are bnsed on the ketene added. Sulfuric acid
was used as the catalyst. With acetylsulfoacetic acid as a cntalyst, greatly increased conversions to the enol acetates are obtained-e.g., with acetone the conversion to isopropenj-1 acetate
is 75 t o 8570 as compared with 35 t o 45% for sulfuric acid catalyst. Anhydrous sodium acetate is also a catalyst for the enol
acetylation of acetone with ketene.
p-LACTOhES
I n the presence of suitable condensation catalysts, aldehydes
and ketones condense with ketene t o form @-lactones. Some of
the better catalyst materials include boric acid, triacetyl borate,
mercuric chloride, zinc chloride, zinc thiocyanate, magnesium
pel chlorate, and boron trifluoride etherate.
Catalysts suitable for use In the condensation of ketene with
carbonyl compounds generally fall within the classification of a
group of salts which are strongly acid in concentrated aqueous
solutions ( I d ) . The compounds are capable of forming coordination complexes with hydroxy groups and also have a strong catalytic activity towards carbonyl derivatives These compounds include the borates, aluminates, halides, thiocyanates, nitrates,
chlorates, and perchlorates of zinc, tin, mercury, aluminum, lithium, boron, iron, manganese, and cobalt.
The inactivity of some salts of this group is generally due to
their insolubility in the reaction solution.
Although this list includes the Friedel-Crafts type of catalyst,
most of the compounds are not Friedel-Crafts catalysts. The cata-
April 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
polyoxymethylene acetates due to the prepence of water in the 95% paraformaldehyde
which is vaporized in the depolymerization
and enters the reactor. Under anhydrous conditions yields of propionolactone as high as 96%
have been obtained.
The reduced pressure reactor (Figure 2) used
in the manufacture of diketene was also used
in the production of lactones.
CONDENSER
PUMP
Figure 1. Condensation Reactor
*
767
lyst activity depends on the solubility of the metal salt as well
as the degree of diwociation in organic media, With aldehydes
and ketones the effective metal salts Can be thought of as forming
an oxonium'type complex with the carbonyl group.
The choice of a catalyst is important if a high yield of @-lactone
is to be obtained. This choice of a catalyst depends on the react i d y of the particular carbonyl compound to be condensed with
ketene. For example, with aldehydes (particularly the lower aliphatic aldehydes, formaldehyde and acetaldehyde, and aromatic
aldehydes) the preferred catalysts are boric acid, triacetyl borate,
zinc thiocyanate, and zinc chloride. Acetone, methyl ethyl ketone, methyl pyruvate, and diacetyl require strong condensation
catalysts such as boron trifluoride etherate or acetic acid complex
to obtain maximum yields. Zinc chloride acetic acid complex and
the metal fluoborates of zinc, iron, and tin can also be included in
this group.
In carrying out the condensation of ketene
with aldehydes continuously, it is preferred to
add the ketene and aldehyde in equimolar
amounts to a solution of the catalyst in the corresponding lactone. Other solvents such as ethers,
alkyl halides, and ketones are also suitable and
are preferred in batchwise operation because of the
polymerization tendency of the @-lactones.
The apparatus shown is charged with 50
grams of zinc chloride in 5 gallons of propionolactone which is circulated through the scrubber,
1, at 1.5 to 2 gallons per minute. Paraformaldehyde is depolymerized at 19, metered through
a heated rotameter, 8, and mixed with gaseous
ketene immediately before entering the scrubber
through the nozzle, 17, which is centered below
the screen supporting the packing. The reaction
temperature is held a t 5' to 10' C. by cooling.
There are two factors on which the choice of a
reaction temperature depends: (1) to obtain a
fast rate of reaction between ketene and formaldehyde so as to minimize the amount of homo
condensations due to the presence of high concentrations of the monomers in solutions, and (2)
to minimize the formation of linear polyesters
of the @-lactone.
In a 48-hour run 3.5 grams of ketene per
minute and 2.5 grams of formaldehyde per
minute were mixed immediately before entering
the scrubber. Catalyst make-up was added intermittently
a t 4 and a concentration of 0.05 to 0.25% was maintained. Propionolactone was taken off continuously a t 25, fed to a flash
heater, and then redistilled. A yield of 88% propionolactone, 3%
acrylic acid, and 9% residue was obtained.
TABLE11. PROPIONOLACTONE
Run
15
16
Conversion
To di- To
Ketene, CHIO, ZnCh, T, To lac- ketene acrylio RedGrams Grams % ' C. tone
acid
acid due
7
15
3050 2142 3
0
78
3
3360 2023
3
10
60
4
12
24
12
6
.2
14
10
1990
1422 0.3 10
84
.
11
5
1095
760
..,
0
3
23
71
1440 1031
. , 40
7
21
.
62
ix :;;i :gig !:: ii !i
20
22
23
I
.
Mole
Ratio
Keten$/
CHzO
1.10/1
1 19/1
1.03/1
1 05/1
1 02/1
1.02/1
0.97/1
PROPIONOLACTONE
Ketene and formaldehyde are metered separately and passed into a solution of zinc chloride
in propionolactone. The solution is cycled through
the column concurrent with the flow of incoming gases and is maintained a t approximately
10' C. by cooling. The lactone is overflowed
continuously through a rotameter to a small flash
heater at reduced pressure. The crude lactone is
then redistilled to remove acrylic acid.
Typical results are reported in Table 11.
It was found that some propionolactone is
formed even in the absence of any catalyst.
Although the temperature was 40" C. in run
23 and 7% propionolactone was obtained, no
acrylic acid was isolated by destructive distillation of the residue. The residue formed in the
presence of catalysts is comprised largely of
Figure 2.
Reduced Pressure Reactor for Ketene Reactions
768
INDUSTRIAL
AND ENGINEERING CHEMISTRY
Vol. 41, No. 4
Table 111. Products from Aliphatic Aldehydes and Ketones
Carbonyl Compound
Formaldehyde
Acetaldehyde
Acetone
Methyl ethyl ketone
Lactone
Propionolactone
P-Butyrolactone
0-Methyl-8-butyrolactone
8-Ethyl-B-butyrolactone
Butyraldehyde
8-Propylpropionolactone
Reduction
Propionic acid
Butyric acid
Isovaleric acid
3-Methylpentanoic acid
Caproic acid
Polymerization and Pyrolysis
Acrylic acid
Crotonic acid
P,8-Dimethylacrylic acid
8-Methyl-p-ethylacrylic acid
8-Propylacrylic acid
Propionolactone can be purified by redistillation at 28" C. and
3 mm. to give a product showing no unsaturation on the infrared
spectrometer. The pure lactone has the constants: n"," 1,4135,
dEo 1.1489, melting point -31.2" C., boiling point 51" C. at 10
mm.
Acetaldehyde and ketene reacted similarly, using a solution of
0.25% zinc chloride in p-butyrolactone. An 85% yield of P-butyrolactone r a s obtained. Diketene and methyl propenyl ketone
are by-products.
With ketones such as acetone and methyl ethyl ketone the reaction is carried out in the presence of excess ketone, which is
recovered and recycled.
CHaCOCHa
+ C H e C = O --+
UNSATURATED ALDEHYDES AND KETONES
1
+ CHt=C=O/ZnCl2
RCH=CR-CR-CHz
1
O--C=O
and
+ CHz=C=O
AHz---C=O
I
O
As the molecular weight increases the problem of isolating the
lactone becomes more difficult because of a tendency to decarboxylation. However, once the p-lactones are isolated in the pure
state, they are stable compounds a t rooin temperature.
If an unsaturated acid is desired as the final product, the reaction between ketene and the carbonyl compound is carried out a t
40 O to G O o C. to give a low molecular weight linear polyester of the
@-lactonedirectly. This linear polyester is then depolymerized
b y distillation t o form the a,p-unsaturated acid ( b , l f ).
+ CHZO/ZnCl2
1
0 t o 10 O 0.
+
$. R C H C R c C R O
I
40" to 60" C.
+
-OCHzCH2CO-
[OCHZCI~ZCO]
-OCH&IIzCO
-CO [OCH~CH~CO],O/CU(OAC)~
A CHz-CHCOOH
--+
I n this particular case a small amount of copper acetate is added
as an inhibitor t o vinyl polymerization prior t o the distillation.
Some of the products which are obtained from aliphatic aldehydes
and ketones with ketene via the p-lactones are listed in Table 111.
I
c=o
CH2
I
+CHaCHzC(CHa)-0
b.p. 60" to 61 C. at 10 min.
CHa=C=O
I-Pentene
Unsaturated aldehydes and ketones can react with lret m e to
give a variety of products. I n the presence of suitable condensation catalysts ketene adds both 1,2 and 1,4 to form p(1)- and
a( 11)-lactones.
b.p. 54" C. at 10 rnm.
CHsCHzCOCHs
Decarboxylation
Ethylene
Propylene
Isobutylene
2-Methvl-1-butene
Furfural gave only tars and uncontrollable reactions with zinc
chloride and similar catalysts. Furacrylic acid and cinnamic acid
were prepared by the reaction of ketene with furfural and benxaldehyde, respectively, a t GOo C. using sodium acetate catalyst followed b y destructive distillation. Yields were 40 to 60%.
4
3 2
RCH=CR-CR=O
CHs-C(CH8)-0
0°C.
I
BF3etherate
CH2----&=0
Alcoholysis ( 9 )
8-Alkoxypvopionic acid
P-Alkoxybutyric acid
8-Alkoxyisovaleric acid
2-Alkoxv-2-methvl
_ uentanoic
.
acid
P-Alkoxycaproic acid
I1
R can be hydrogen, alkyl, or aryl.
The &lactones are decarboxylated b y pyrolyzing 0.r heating at
temperatures above 100" to 120" C. to form diene derivatives.
&Lactones decarboxylate a t slightly higher temperatures and
also form diene derivatives.
RCH=CR-CR-CH2
1
0-Lo
RCHCR=CRO
I
CHz-----C=O
I
RCH=CR--CR=CH2
A
+
Cod
--f
A
+
CHz=CR--CR=CHR
+ COz
P-Lactones are usually formed in the ratio of 10 to 1 of the delta
lactones as calculated from the yield of olefinic decomposition
products obtained from the condensation of crotonaldehyde with
ketene (Table IV). If a doubly unsaturated acid is the desired
product, the condensation is carried out a t 40' t o 50" C. and a
product is obtained comprising largely the linear polyesters of the
lactones. Destructive distillation a t reduced pressure result5 in
the formation of the doubly unsaturated acid. Sorbic acid is
manufactured in 70 to 80% yields in this may from crotonaldchyde
and ketene.
With enol esterification catalysts, and a t 50" to 80" C., the wrresponding acetoxy dienes are formed. For example, 1-ace1oxy-
AROMATIC ALDEHYDES AND KETONES
Benzaldehyde and acetophenone reacted with ketene; boric
acid and zinc chloride were used as catalysts at, 0 O to 10' C. Decarboxylation gave good yields of styrene and a-methylstyrene,
respectively.
CsI15CHO
+ CH-C=O
--+ CeHsCHCHzC=O
L-0-J
Acetone was uaed as diluent in the benzaldehyde reactioii. The
yield of styrene was approximately three times as much with
boric acid catalyst as with sodium acetate. The aromatic ketones
gave no reaction with sodium acetate catalyst.
CsH&HCHzC=O
'-02
A CBH~CH=CHZ
KaOA4c12%, &BO3 34%
+
TABLE
IT'.
U S S A T U R A T E D -4LDEHYDES AND l<ETOKES
Condensation Condition-50' to 60" C .
followed by deCarbonyl
followed by
Compound
decarboxylation
polymerization
Crotonaldehyde 387, Piperylene
Sorbic acid
4% Isoprene
0" to 10' C .
Methacrolein
Isoprene
Ethacrolein
Z-F,thyi-l&butadiene
Methyl vinyl
ketone
Methyl isopropenyl ketene
Isoprene
2,3-Dimethyl-1,3butadiene
1,2-Dimethyl-1,3butadiene
4-hIetiiyl-2,4pentadienoic
acid
4-Ethyl-2,4pentadienoic
acid
Enol Acetylation
Conditions
l-Acetoxy-1,3butadicne, b.p.40
6 0 - 6 1 O C.
No reaction
1-Acetoxy-2-methyl1,3-bntadiene,
b.p.40 67' c.
2-Acetoxy-l,3-butadiene, b.p.io 54' C.
''-Ace toxy-3-me thyll,a-butadiene,
b.p.ro 62' C.
I
169
INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1949
1,a-butadiene is produced by the reaction of ketene with crotonaldehyde in the presence of sulfuric acid a t 60 O t o 80 O C.
+ CHaCH=CHCHO/HzS04
CHZ=C=O
60-80 O C.
CH2=CHCH=CHOCOCHs
Some of the products which have been formed with the common ~ l , unsaturated
p
aldehydes and ketones are reported in Table
IV.
All these products are useful in resins, drying oils, etc. The
enol acetates form both rubbers and resins and can be polymerized and copolymerized.
@-lactoneincreases, and higher yields of the unsaturated esters are
obtained. Hydroxydicarboxylic acids can be formed by hydrolysis of the crude lactone, and with alcohols the corresponding alkoxydicarboxylic acid diester is produced.
HYDROLYSIS
CH&(CHg) --CHzCOOCzHs +
NaOH, HC1
O=LB
HOOCCHzC(CHs)-CH&OOH
+
+ CzH5OH
AH
ALCOHOLYSIS
DIKETONES
Ketene condenses with diketenes to form the mono- and di-plactones. I n the absence of excess ketene the decarboxylation
products indicate the formation of both the mono- and di-&lactones.
For example, 86 grams of diaoetyl were diluted with 250 ml. of
ethyl ether containing 12 ml. of boron trifluoride etherate and 2
ram moles of ketene were passed in through a high speed stirrer.
!!he catalyst was neutralized with anhydrous sodium acetate and
the mixture was distilled a t atmpspheric pressure. Four grams of
2,3-dirnethyl-lJ3-butadiene,
bo.il?ng point 68 O Cb!and 12 grams of
methyl isopropenyl ketone, boihng point 95-98 C. were isolated
in addition to 47 grams of unchanged diacetyl.
CH3COCOCI33
+ 2 CHz=C=O
o o c.
BFetherate-)
CZH~OOCCH~C
(CHI)-CHzCOOC2Hs
dCaHs
Enol acetylation of methyl pyruvate gave a low yield of methyl
a-acetoxyacrylate. Ethyl acetoacetate and ethyl levulinate led
to a mixture of isomers-e.g., with acetoacetic ester.
+ CHz=C=O/HzSO4
CH&OCHzCOOC~Hs
0
'
CHz==C--CHz
CHzC(CH3)COCHs
6=L-0
CHzC(CHs)C(CHJ CHo
o= A '
-0
60-80
A
C
0
bOCz& + CHsC=CH E OCzHs
bCOCH8
bCOCH3
A-d-o
The enol acetates of acetoacetic ester rearrange
on prolonged heating in the presence of acid catalysts
to form ethyl diacetylacetate. This compound boils
slightly below the mixture of enol acetate isomers
o= -0
and has a higher index of refraction n2: = 1.4690
CHpC(CHs)~(CHa)~&
+ CHz=C(CHdC(CHs)=CH2 4- 2 0 2
as compared to 1.4420 for the enol acetate isomers.
I
I
The enol acetates of the ketoesters can be copolyo=LO
a--(5=0
merized with polymerizable vinyl monomers in the
Degering (16)and Hurd ( 7 )both reported the acetylation of the
presence of peroxide catalysts to give clear, colorless resins. Some
'
enol forms of diketones with ketene in 1944. It is interesting to
of the compounds which can be prepared from keto esters and
ketene are reported in Table VI.
note that whereas the mono and dienol acetates of diacetyl and
,
acetylacetone can be prepared, acetonylacetone is only cyclized
under acetylation conditions and no enol acetates have been isolated. Under condensation conditions the decarboxylation prodTABLE
V. REACTION
PRODUCTS
OF KETENEWITH DIKETONES
ucts of both the mono- and di-@-lactonesfrom acetonyl acetone
Carbonyl
Condensation Conditions
and ketene were isolated. The products of the reaction of ketene
Compound
Decarboxylation Product;
Enol Acetylation Produots
with diketones under both condensation and enol acetylation
Diaoetyl
14% methyl isopropenyl 4% or-acetoxyvinyl methyl
ketone
1.7%
ketone,
2 3-diacotoxy-1
b.p.5 3 Z e C.3conditions are summarized in Table V.
5% 2 3-dimeth~l-l.3-butaCH&(CHJCOCHs
A'
+
-+A
+
CH~=C(CH~)COCHI COz
*
Methyl pyruvate, ethyl acetoacetate, and methyl levulinate
also reacted with ketene under condensation and enol acetylation
conditions. No effort was made to isolate the 8-lactones but the
decarboxylation products were isolated instead. Methyl pyruvate reacts with ketene to form a &lactone, which is then decarboxylated to form methyl methacrylate.
+ CHa==C=O/BF3 etherate 0 ° C
CHsCOCOOCHa
__.f
CHa C(CHa)COOCH~
o=c-'
CHz--C(CHs)-COOCH3
I
/
dieie, b.p.rss 68' C.
27% 4-methyl-4-penten-2one b.p.785 127' C.
14% '2,4-dirnethyl-l 4-pentadiene, b.pm 8 8 O ' C:
butahiene, b.p.6 53&C.
43% I-methyl 2-acetylvinyl
acetate, b.p.10 84O C.
18% 2,4-diacetoxyplperylene, b.p.la 114' C.
2,5-Dimethyl-l,5-hexa&ene, 85% 2,5-dimethylfuran
5-Methyl-5-hexene-Z-one,
b.p.?84 112'
Aoetylacetone
KETO ESTERS
b
Acetonylaoetone
TABLEVI.
Carbonyl
Compound
Methyl
pyruvate
Ethyl
acetoacetate
+CH2=C(CHs)-COOCH3
O=%-d
Ethyl acetoacetate and methyl levulinate undergo the same
condensation to form unsaturated esters. As the carbonyl group
is removed from the carboxyl group the ease of formation of the
c.
b.p.784 154'
Methyl,
levulinate
Ethyl
levulinate
c.
PRODUCTS
OF KETOESTERS
AND KETENE
Condensation Conditiono,
Deoarboxylation Products
Enol Acetylation Product
14% methyl methacrylate Methyl a-acetoxyacrylate,
b.p.io 62" C.
84% ethyl isopropenyl- 70% ethyl 3-acetoxycrotonate
acetate, b.p.eo 54.5' C.,
and isomer, b.p.to 94O C.,
nv 1.4400, d$' 1.0159
nZ,O 1.4420, dgg 1.0659
Ethyl diacetylacetate, b.p.10
89' C.. ny 1.4690
Methyl 8-isopropenylaropionate; b.p.zo 54' C.,
ny 1.4224, d g 0.9346
38% ethyl 4-aoetoxy-4-pentenoate and isomer, b.p.6
8Q0 C.,n2,O 1.4361, d i z 1.0478
'
INDUSTRIAL AND ENGINEERING CHEMISTRY
770
Vol. 41, No. 4
REACTIOR O F KETERE WITH HYDROCYANIC ACID (8, 1 8 )
The reaction of ketene with hydrocyanic acid shows the formation of an enolizable kctonitrile (IC)which is subsequently acetylated to form the enol acetate. The reactions which occur are
represented b y the equations
CH*=C=O
+ HCN +CH3COCN +CII2=C(OH)CN
I'II. REACTION
OF T C s m m
Conversion,
S o catalyst
0.0870 XaOAc
0 . 3 4 , KaOAc
0.457, NaOAc
then
CHZ=C(OH)CK f CH2=C=O
TABLE
58
88
67
HYDROCYANIC
ACID
yo
Ketene
t o diIICN Ketene ketene
24
40
44
42.5
70
14
70
VI'ITII
0.1
2.5
Ketene Resin
Yield, % of'
c70
Total
78
74
88
66
6.5
18.0
8.7
30
Average
12 runs
12 runs
7 rnns
12 rnns
Acetoxyacrylonitrile
Yield on
Ketene,
%
34
60
88
63.5
CHz==C(OCOCH,)CS
I n addition to a-acetoxyacrylonitrile a small amount of the
dimer of pyruvonitrile is also formed
H~
2CHaCOCN -+ C H J C O ~ C ( C N ) ~ Ca-acetoxyisosuccinic
dinitrile
The dimer can be pyrolyzed a t elevated temperatures or distilled in the presence of basic catalysts such as sodium acetate to
* yield a-acetoxyacrylonitrile and hydrocyanic acid.
The reaction of ketene with hydrocyanic acid is carried out by
passing ketene into hydrocyanic acid in the presence or absence of
diluents, a t -10" to +loo C. Diluents are used mainly to reduce
the vapor pressure of the hydrocyanic acid and a-acetoxyacrylonitrile itself is a preferred diluent for the reaction. Although considerable reaction is obtained in the absence of catalyst, the highest yields are obtained with a mildly basic catalyst. Anhydrous
sodium and potassium acetate are superior t o the alkali cyanides
and tertiary nitrogenous compounds as catalysts.
I n this reaction an optimum concentration of catalyst has been
observed. With no catalyst or too low a concentration of catal j r s t , diketene is formed in large amounts. With too high a concentration of catalyst the dimerization of pyruvonitrile increases
and considerable amounts of a-acetoxyisosuccinic dinitrile are
formed.
A comparison of average results with and without sodiuni acetate catalyst is reported in Table VII. These runs were carried
out operating continuously using the column shown for dilcetene
and propionolactone (Figure 1). Unreacled hydrocyanic acid
was separated from the product by distillation and recycled to the
reactor, The residue was mainly a-acetoxyisosuccinic dinitrile.
a-,~cetoxyisosuccinicdinitrile can be formed alniost t o the exclusion of a-acetoxyacrylonitrile by carrying out the reaction
with hydrocyanic acid as a 50% solution in acetic acid a t 0" C.
and with 0.370 sodium acetate catalyst. Less than 10% acetic
anhydride is formed as a by-product.
LITERATURE CITED
Boese, A. B., U. S. Patent 2,108,427 (Feh. 15, 1938).
Ibid.,2,382,464 (Aug. 14, 1945).
Dommoni, T. F., and Cuneo, J. F., Zbid., 2,411,823 (Nov. 26,
1946).
Gwynn, B. H., and begering, E. F., J . Am. Chem. SOC.,64,
2216
(1942).
Gwynn and Degering, U. S. Patent 2,383,966 (1942).
Hurd, C. D., J. Am. Chem. SOC.,55, 275 (1933).
Hurd, C. D., Edwards, E. E., and Roach, J. I<.,Ibid.,66,
2013
(1944).
Johnston, F., and Newton, L. W., U. S. Patent 2,395,930 (March
6, 1946).
Kung, F. E.,Ibid., 2,352,641 (JuEy4, 1944).
Ibid., 2,356,459 (Aug. 22, 1944).
Ibid., 2,361,036 (Oct. 24, 1944).
hfeerwein, Ann., 455, 227 (1927).
Mugdan, M., and Sixt, J., U. S.Patent 2,216,450 (Oct. 1, 1940).
Roy, G. C., Ibid.,2,396,201 (March 5, 1946).
Spence, d. A., and Degering, E. F.,J . Am. Chem. Sac., 66, 1624
(1944).
Staudinger, Ann., 384, 51 (1911).
Staudinger and Kon, Ibid., 384,38-135 (1911).
Trollman, Schlaffer, and Ostrowski, German Patent
736,504
(1943).
RECEIVEDMarch 8, 1948. Presented in the Symposium on Industrial
Processes, American Bssociation for the Adranoemont of Science, Chicago,
Ill., December 2 6 , 1947.
Relations for
J. W. WILSON AND GEROULD H. SMITH
Union Oil Company of California, Oleum, Calif.
A
MARKED advance in the measurenient of the viscous properties of lubricating greases was disclosed by Arveson (1)
in papers published in 1932 and 1934. His results were obtained
on a novel apparatus employing constant flow rate rather than
constant pressure. Beerbower, Sproule, Patherg, and Zimmer
( 2 ) have developed a simplified apparatus of lhis type in n-hich
constant f l o ~
rate is obtained by means of hydraulic oil and an
accurate metering pump. This apparatus, which is known as the
S.O.D. pressure viscometer (Precision Scientific Company, Chicago, Ill.) has led to a large amount of work on the flow characteristics of lubricating greases (e,.$,8,9, 11, 13).
Arwson used his data to calculate consistency values, which he
termed "apparent viscosity," v a , by means of the Poiseuille
equation :
As lubricating greases are non-Kewtonian in character, different values of qa will be obtained for a grease a t diffcrcnt rates of
flo~
in a given capillary, or a t a given rate of flow in capillarics
with different radii. Arveson showed that by plotting q a against
the expression 4Q/n-IP, most suitably on logarithmic scales,
smooth curves could be obtained. This expression, 4Q/n-R3, Cali
he shown mathematically to be the rate of shear, S, a t the wall of
a capillary for the flow of a Nevtonian fluid. For a lion-Sewtonian fluid, the cxprcssion only approsirnates the rate of shear at,
the wall; nevertheless, there are abundant data obtained with
the S.O.D. viscometer t'o indicate that if the dimensions of two