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An Acylal of Dimethylketene.

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Further preparative and kinetic studies are necessary before it can be decided whether N-halogen compounds
(R-NHX) react via nitrenes or by a nucleophilic substitution mechanism. The same is true for the conversion with
ferrous oxalate at about 300 "C of 0-nitrobiphenyl [72]
or o-nitrobiphenylamine [73] into carbazole (58) and
9,lO-dihydrophenazine (59), respectively, and for the
transformation of 2-(o-nitrophenyl)pyridine into ammonium nitreniate (60). The latter is also formed on
thermal decomposition but not on exposure to ultraviolet radiation of 2-(o-azidophenyl)pyridine [74].
Both the reactions leading to (58) through (60) and the
conversion of 2-ethylnitrobenzene into cis-2,2'-diethylazobenzene (61) and o-elhylaniline (62) take place on
the surface of the ferrous oxalate. However, nitrenes and
carbenes formed on surf;\ccs differ from the free forms
by their lower energy contcnt and by the stereogeometry
imposed by the interface. Chemisorbed fragments of the
above type should thereforc be differentiated from their
free forms.
The same reservation applies to the assumption that
elimination of oxygen, e.6. from o-nitrosobiphenyl by
triethyl phosphite to give carbazole (63), occurs via
nitrenes [75].
H
163)
[72] H. D. Waterman and D. L. Vivian, I. org Chemistry 14, 289
(1 949).
[73] D.L. Vivian, D . Y . Greenberg, and J.L. Hartwell, J. org. Chemistry 16, 1 (1951).
[74] X. A . Abramovitch, Y . Ahmad, and D . Newman, Tetrahedron
Letters 1961, 752.
We wish to tliunk the Drrt/scht Forscf~urrgsgenieinsch~ft
,jbr supportitp our p}~otocJrc.itricril
investigctions.
ReceiVcd. Ihxember IZth, 1962 [A 307/1101El
German vcrsion: Angew. Chem. 75, 707 (1963)
[75] P. J. Bunyan, and J. 1. Cidogun, Proc. chcm. SOC. (London)
1962,78; I.I . G , Cudogon and M. Cameron-Wood, ibid. 1962,361
P.J. Bun.van and J. I.G. CadogmJ, J. chem. SOC.(London) 1963,42,
An Acylal of Dimethylketene
BY DR. H. BESTIAN AND DR. D. GUNTHER
FARBWERKE HOECHST AG., FORMERLY MEISTER LUCIUS AND B R u N ING,
FRANKFURT/hIAIN-HoCHST (GERMANY)
Dedicated to Profissor Dr.-Ing. Karl Winnacker on the occasion of his 60th birthday
Free dimethylketene is difficultto handle because of its tendency to dimerizc even at l11w
temperatures and to form explosive peroxides with atmospheric oxygen. In contrast, thc
dimethylketenacylal of dimethylmalonic acid is simple and safe to use. This cornpowid
aflords dimethylketene on thermal or catalytic cleavage, hence, it can replace the , f r w
ketene in nearly all reactions. The synthesis and reactions of this acylal are described.
Introduction
Ketenes were first investigated by Sfaudinger, who
synthetized diphenylketene and dimethylketene [1,2].
The parent compound of this class of substances, ketene
[3], was prepared a few years later and became an im[ I ] H.Stuudinger, Ber. dtsch. chem. Ges. 38, 1735 (1905).
[2] H. Stuudinger and H . W . Klever, Ber. dtsch. chem. GCS.3Y,
968 (1906).
[3] N.T. M. Wilsmore, J. chem. SOC. (London) 1907, 91.
608
portant industrial chemical. Surprisingly, for a long time
dialkylketenes attracted liitle attention, despite the fact
that they are comparable in reactivity to ketene. However, recent publications, particularly on dimethylketene
[4-11], indicate renewed interest in these compounds,
[4] G. Natta, G. Mazzanti, G . I:. Pregagliu, M . Birtaghi and M .
Peraldo, J. Amer. chern. SOC.82,4742 (1960); Makromolekulare
Chem. 44/46, 537 (1961).
[j]R . H . Hasek, R . D . Clark aiid .I. H . Chuitdel, J . org. Chemistry
27, 60 (1962).
Angew. Chern.
illtormi/.
Edit. 1 V d . 2 (1963)
1 No. I0
which nobody had used since Staudingrr's classical
studies.
Work with dimethytketene is complicated by its great
tendency to polymerize. Even at low temperatures, it is
readily converted into tetramethyl-l,3-cyclo butanedione.
In contrast to ketene, it rapidly forms highly explosive
peroxides [12] even with atmospheric oxygen.
Attempts to prepare dimethylketene from dimethylmalonic acid by a simplified procedure gave a stable
crystalline compound, shown by our investigations to be
the dimethylketenacylal of dirnethylrnalonic acid ( I ) .
(CH3)&=C(
0 -c,o
C(CH&
/
0-CO
(I)
This compound is simple and safe to handle and can be
converted readily into dimetliylketene by thermal or
catalytic cleavage. In nearly all cases, this acylal can be
used in place of free dimethylketene.
after recrystallization from pctroleuni ether, melts at
80 'C. The yield was about 80 y!, based on the dimethylmalonic acid charged.
The purecompound C9H1204which is readily obtainable
by this method is thermally quire stable. It can be heated
to boiling at atmospheric pressitre for a short time without appreciable decomposition. Catalytic amounts of
alkaline agents promote rapid decomposition into dimethylketene and carbon dioxide already at about
100 OC.Thc compound does not react with oxygen under
normal conditions; it is quite stitble towards atmospheric
moisture, so that it can be stored and handled without
special precautions.
On heating dimethylmaIonic anhydride in a sealed tube
in the presence of a trace of trimethylamine, Stuudinger
[I41 obtained a compound CoH12O4 (m.p. 78 "C), to
which he assigned the formula of tetramethylacetonedicarboxylic anhydride [2,2,4,4-tetramethyl-3-ketoglutaric
anhydride] (2). Comparison ol' this compound with the
I. Preparation a n d Elucidation of Structure
Ott [I31 and Stuudinger [ 141obtained the polymeric anhydride of dimethylmalonic acid on dissolving dimethylmalonic acid in excess acetic anhydride and evaporating
the mixture to dryness in vucuo. On heating to about
100"C,the residue undergoes decomposition to dimethylketene and carbon dioxide.
I n a modification of this procedure, we heated dimethyl-
malonic acid with acetic anhydride to only about 60 "C
while continuously removing the resulting acetic acid
formed by distillation at 20 nim pressure over a column.
The dimethylmalonic acid dissolves rapidly during this
process. Surprisingly, when the acetic acid produced
(2 moles) is completely removed from the reaction mixture, a rapidly increasing evolution of C02 begins, as
indicated by a rise in pressure. This evolution continues
even when the reaction mixture is brought to normal
pressure and allowed to cool ;it subsides only after 1 mole
of C02 is liberated per 2 moles of dimethylmalonic acid.
When the excess acetic anhydride is distilled off in vacuo,
a residue of a crystalline compound is obtained which,
[6] G . F. Pregaglia, G. Mazza/iti and M . Binaghi, Makromolekulare Chem. 48,234 (1961).
[7] J. L. E. Erickson and G . C. Ki#chms,J . org. Chemistry 27,460
(1962).
[8]R . H. Hasek, E. U.Elam, J . C . Martin, and R . G. Nations, J .
org. Chemistry 26, 700 (1961).
[9] R . H . Hasek, R . D . Clark, and J . H . Chasder, J. org. Chemistry
26,3130(1961); R . H. Hasck, E. U. Elam, and J. C. Martin, ibid.
26,4340 (1961); R . H . Hasck, E. U. Elan?,J. C. Martin, and R . D .
Clark, ibid. 27, 60 (1962).
[lo] R . G. J . Miller, E. Nieltl, and A.Turner-Jones, Chem. and
Ind. 1962, 181.
[ I l l Belg. Pat. 595298 (Sept. 22nd, 1960). Eastman Kodak Co.,
inventor: R. H . Hasek and E. U.Ekam.
[I21 H . Staudinger: Die Ketcnc. F. Pnko, Stuttgart 1912; Org.
Syntheses 33, 30 (1953).
[I31 E. Ott, Liebigs Ann. Chcm. 401, 175 (1913).
(141 H. Staudinger, Helv. chim. Acta 8, 306 (1925).
Angew. Chcm. internat. Edit. / Vol. 2 (1963) / No. I0
substance obtained by our method showed that both are
identical. This applies to the reactions and to the
physical properties.
However, some of the reactions we had carried out
showed that the compound cannot possess the structure
(2) assigned to it by Stuudinger. We concluded that the
compound must have the structure of the hitherto unknown acylal ( I ) of dimethylmaIonic acid; our conclusion is based particularly on the results presented in
the following discussion.
1. Nuclear Magnetic Resonance
The N M R spectrum shows t w o equally strong signals
for methyl groups. This result is in agreement with structure ( I ) but not with structure (2), for which only
o n e signal would be expected for all methyl groups.
2. Action of Bromine
In carbon tetrachloride, the compound adds on one
mole of bromine. x-Rromoisobulyryl bromide and polymeric dimethylmalonic anhydride were isolated as the
reaction products in nearly theoretical yields. The formation of these products can be readily explained by
assigning structure ( I ) to the skirting compound:
609
3. Ozonization
The reaction with ozone in methanolic solution at -78 "C
followed by treatment of the primary ozonization product with sodium iodide [15] afforded 0.75 mole of acetone.
4. Hydrogenation
Lithium aluminum hydride induced reductive cleavage
of the molecule. One mole cf isobutanol and 1 mole of
2,2-dimethyl-1,3-propanediol were isolated.
partially entrained by thc COZ stream and lost. If the
evolution of CO;?is allowed to occur in vacuo, under
otherwise identical conditions, the yield of dimethylketenacylal drops markedly and large amounts of dimethylketene are found in the cold traps. This indicates
that free dimethylketeneparticipates in the formation of
the acylal.
The formation of (1) can therefore probably be explained by assuming that the dimethylketene resulting
from cleavage of the dimethylmalonic anhydride adds
onto unreacted anhydride still present in the system (a).
II. Mechanism of the Formation of the
Dimethylketenacylal
a
Staudinger [14] summarized his findings concerning the
cleavage of dimethylmalonic anhydride in the following
reaction scheme.
gentle heating +N(CH&
' /co
\
(CH3)2C\ lo
co
-
i
N(CH&
(':H3)zC=C"
+
' O Z *basting
*
in v m ~ o
(CHS)f-C\O
p
OC\
(CH,)zC-CO
+
'OZ
\
L
heating under pressure
I
t C H s ) Zco
C~(CHs)z
besting under pansure
Our observations regarding the preparation of the dimethylketenacylal permit us to throw some light on the
question whether the above scheme requires alterations
The assumption that the monomeric, cyclic form of dimethylmalonic anhydride exists in equilibrium with its
oligomeric forms in the acetic anhydride solution used
in the synthesis is supported by the fact that dialkylmalonic anhydrides have recently been isolated as monomeric compounds [16].
The fact that the dimethylketenacylal of acetic acid (3)
was obtained as a by-product in the preparation of the
dimethylketenacyla, of dimethylmalonic acid in acetic
anhydride solution at 60-80 "Calso lends support to the
assumed reaction schemc (a). The formation of this
hitherto unknown compound can readily be explained
on the basis of addition of acetic anhydride onto dimethylketene (b, 1).
The formation of the dimcthySicetenacyla1 of acetic acid
(3) is hindered by the fact that, particularly above 80 "C,
\
when (2) is replaced by the ketenacylal structure (1).
Experimental results indicate that two changes should
be made:
1. The dimethylketenacylal (I) is also formed when trimethylamine is not present as catalyst during the cleavage
of dimethylmalonic anhydride. It is merely important
that the C02 is liberated at low temperatures. The presence of a catalyst is not necessary.
2. It seems unlikely that the dimethylketenacylal (I) is
formed by recombination of the cleavage products, viz.
dimethylketene and C02, in a 2: 1 molar ratio. Attempts
to make dimethylketene and C02 undergo this reaction
have been unsuccessful.
During the preparation of the dimethylketenacylal of
dimethylmalonic acid, dimethylketene is formed alongside the carbon dioxide even at room temperature and is
[IS] G.Lohaus, Ph. D. Thesis, TechnischeHochschuleKarlsruhe,
1952.
610
(CH&CH-COUCD-CHs
+
CH3-C-
+
CHz=CO
dark resinous
-XO-CHs
products
the competing reaction (b, 2) becomes more and more
predominant. Thus, the cxtremely reactive compound
dimethylketeneis obviously capable of adding on a proton from the CH3 groups of the acetic anhydride to its
anionic C atom. Ketene is formed and is converted
rapidly into dark products, together with the mixed anhydride of isobutyric acid and acetic acid, which on distillation rearranges to the two symmetric anhydrides.
The undesirable side-reaction (b, 2) does not take place
when acetic anhydride is replaced by isobutyric anhydride. When the latter is employed as dehydrating
agent in our method of preparation of the dimethylketenacylal (I), not the slightest discoloration is ob[16] A . C. Duckworth, J. org. Chemistry 27, 3146 (1962).
Angew. Chem. intcrtrcit. Edit. / Vol. 2 (1963) / No. 10
served during the evolution of the C02, the yield of
product is greater, and its purity is greater.
A simplified method for the preparation of dimethyl
ketene in high yield from dimethylmalonic acid is based
on these observations. Dimethylmalonic acid is dehydrated with an excess of isobutyric anhydride at
50-60 "C with continuous removal of the resulting isobutyric acid by vacuum distillation over a fractionating
column. At higher temperatures, the anhydride solution
readily undergoes cleavage to dirnethylketene and C02
without forming by-products.
111. Reactions
The dimethylketenacylalof dimethylmalonicacid is relatively stable to hydrolysis. Water has no visible effect on
this compound at room temperature. It dissolves only
slowly even in boiling water, yielding isobutyric acid and
dimethylmalonic acid (Reaction c, 1). Hydrolysis is
markedly accelerated by mineral acids or alkali.
In this method, the dimethylketenacylal splits almost
without a residue and affords a nearly theoretical yield
of dimethylketene. The proccdure is safe and permits
convenient preparation of large mounts of dimethylketene in the laboratory.
2. Reactions with Alcohols and Phenols
The dimethylketenacylal exhi hits remarkable stability
toward alcohols and phenols. I t can thus be recrystallized
.
without loss from low-boilingalcohols, ~ . gisopropanol.
No alcoholysis to the isobutyric ester and dimethylmalonic monoester was observed. The reaction with alcohols or phenols, like the decomposition of the dimethylketenacyial itself (see Section I), is markedly accelerated in the presence of alkali carbonates (Figure 1).
1000
/
L-4
i
m
D1
We made the surprising observation that alcoholysis,
and in many cases also aminolysis, do not proceed in
the expected direction. Instead, cleavage of the acylal
into dimethylketene and carbon dioxide takes place
(Reaction c, 2), and the reaction products are exclusively
those of dimethylketene. The course of this reaction indicates that the dimethylketenacylal behaves like dimethylketene itself. It can be used as a starting material
for the preparation of dimethylketene, but it can also be
used to carry out reactions with nascent dimethylketene
(formed in situ).
1. Cleavage into Dimethylketene and Carbon Dioxide
The thermal cleavage of the dimethylketenacylal (I) is
slow even at its boiling point (about 180 "C). This cleavage is markedly accelerated by addition of small amounts
of alkaline agents, best among which are the alkali carbonates. These catalysts permit reduction of the cleavage
temperature to 100-150 "C and cause rapid decomposition in this range. The reaction is best carried out by
dropwise addition of the molten dimethylketenacylalto
a small amount of potassium carbonate contained in a
glass vessel which is heated to 150 "C. The rate of addition should correspond to the rate of cleavage desired.
The gaseous cleavage product, which constists of 2 parts
by volume of dimethylketene and 1 part by volume of
carbon dioxide, can be used directly for reactions requiring diniethylketene. If desired, the dimethylketene can
be readily isolated in liquid form by partial condensation
of the gas stream, the escaping carbon dioxide providing
protection from atmospheric oxygen.
Angew. Chem. internat. Edit. / Vol. 2 (1963) / No. I 0
2
3
4
5'
6I
71-
Fig. 1. Kinetics of carbon dioxide liheration in the reaction of the
dimethylketenacylal of dimethylmaIonic acid with t.-butanol and the
effect on same of potassium carbonate (acylal: 0.1 mole; temperature:
83 "C). After 4 hours, 0.1 g of KzCO3 was added (arrow o n the curve).
Ordinate: Quantity of COz evolved [nil].
Abscissa: Reaction time [hours].
The overall reaction can be explained only by assuming
that the reaction with the alcohol is preceeded by cleavage of the acylal to dirnethylketen. This is indicated by
the fact that the acylal remained essentially unaltered
after several hours in boiling t-butanol. Only a small
fraction, equivalent to the carbon dioxide produced, was
found to have been converted into the isobutyric ester.
In all the cases studied, the reactions of the acylal with
alcohols and phenols proceedcd without side reactions,
giving the isobutyric ester i n nearly theoretical yield
(Table 1).
Table 1. Reactions of the dimethylkclenacylal of dimethylmalonic
acid with alcohols and phenols
f
coz
~ROH
n-Butanol
t-Butmol
Cyclohexanol
Ally1 alcohol
Ethylene glycol
2,2-Dimethyl-l,3propanediol
Phenol
Cinnamic alcohol
Molar ratio Temp.
U0H:(I)
"'C]
(CH&CH-COOR
B.p.
Yield
[ "CI
I %I
-
2.5
2
150
1
1
160
I60
155
127
204
133
132/20 mm
238-240
2
2
I40
120
103/20 mm
I1712 mm
I00
95
97
90
95
98
92
95
88
611
3. Reactions with Amines
In contrast to alcohols, amines react vigorously with the
dimethylketenacylal (I) already at room temperature.
The reaction with aniline results in aminolysis and, as
already described by Staudinger [141, isobutyranilide and
dimethylmalonic monoanilide are formed. Butylamine
and cyclohexylamine behave similarly. On the other
hand, the reaction with secondary amine occurs with
Table 2. Reactions of the dimethylketenacylal of dimethylmalonic acid
with amines
PC?
R1\
(CH&C=C
C(CH3)Z + 2
NH
R1/
b-C6
-
/R1
2 (CH&CH-CO-N,
R2
+CG
(1)
Diethylamine
Dibutylamine
Piperidine
N-Methylaniline
30
30
20
80
2
2
2
2
ll0/50
123/11
114/15
75/0.2
90
96
91
93
ether and cyclopentddiene [ I 71. In the case of these relatively reactive compounds, addition takes place with
formation of the corrcsponding 2,2-dimethylcyclobutanone derivatives. Attempts to react styrene with dimethylketene failed and it was assumed [I71 that the
rates of polymerization I'or dimethylketene and for
styrene are too high cornp;ired to the rate of addition.
We have investigated the possibility of adding dimethylketene onto a carbon-carbon double bond to form a
cyclic compound. The source of dimethylketene was the
dimethylketenacylal of tlimethylrnolonic acid (I).
Table 3 presents descriptions of reactions with olefins
which, in all the cases investigated by us, yielded the anticipated cyclobutanone derivatives.
The reaction is carried out by heating the dimethylketenacylal with the olefin, the latter being preferably used in
excess. The addition of catalytic amounts of alkaline
substances results in lower reaction temperatures.
The reaction with gaseous olefins is carried out
Table 3. Reactions of I hc dimethylketene acylal with olefins.
evolution of COZ.and exclusive formation of isobutyramide. In this case, preliminary decomposition to dimethylketene must again be assumed. The examples of
this reaction investigated so far are listed in Table 2.
(5)
___Product ( 5 )
Molar ratio
Olefin (4)
Ethylene
Propylene
i-Butylene
2-Butene
2-Methyl-2-butene
I -Decene
Cyclohexene
Styrene
Butadiene
1
(4):fl)
4
5
6
4
4
7
8
Temp.
t "CI
140
I30
I40
140
130
120
120
120
140
4. Reactions with Carboxylic Acids
(I)
+ 2 R-COOH
coz\2 [(H~C)zCH-CO-O-CO-Rl
distillation
-+[(H+~)~CH-COIZO+ (R-CO)zO
In this reaction too, carbon dioxide is evolved. In the
presence of alkali carbonates or alkali salts of carboxylic
acids, the reaction occurs readily at 12OoC. It may be
assumed that the dimethylketene initially produced
reacts first with the carboxylic acid to give the mixed anhydride, which on distillation undergoes disproportionation to isobutyric anhydride and the anhydride of the
carboxylic acid used. Since the reagents are used in
stoichiometric amounts, and the isobutyric anhydride is
readily removed by distillation, this method may offer
preparative advantages in the synthesis of carboxylic anhydrides from carboxylic acids.
5 . Additions onto Olefins
The reaction of dimethylketene with the carbon-carbon
double bond has hitherto received little attention. Staudinger described the reaction of dimethylketenewith vinyl
612
+ coz
B. p.
Yield
[ "CI - t %I
-
Deri va ti vcs
- ~-
108
138
I55
150
171
88/1 mm
68/5 nim
88/1 m m
91/100 mm
60
72
70
40
30
67
32
40
50
2,4-Dinitro1~henylhydrazone
m.p. 140-141 "C
2,4-Dinitroivhcnylhydrazonem.p. 96-98 "C
2,4-Dinitro1~henylbydrazone
m.p. 116- 117 "C
Semicurbazwie m.p. 186-187 "C
Semicarbaztine m.p. 184-.186"C
Semicarbamnc m.p. 114-1 15 "C
Semicarbazone m.p. 216-7217 "C (decomp.)
Semicarbazone m.p. 189-191 "C
Semicarbazirns m.p. 188-189"C
under pressure Jreferably in a solvent) in order to increase the olefin concentration and to ensure reaction in
a homogeneous phase. The cyclobutanone formed can
be isolated by distillation.
The structures of these hitherto unknown cyclobutanone
derivatives were elucidated using the product obtained
from the reaction of the rlimethyIketewacyla1 and isobutylene as an example. The expected product was
2,2,3,3-tetramethylcyclobu~anone (6), rather than
2,2,4,4-tetramethylcyclobulnnone (7).
When the cyclobutanone dcrivativeobtained from the reaction with isobutylene was oxdized with hydrogen peroxide in aqueous potassiuin hydroxide, the product was
ay-lactone, which proved t o be identical with the 3,3,4,4tetramethylbutyrolactone (8) described by Baumgarten
1171 H.Sfaudinger and P. J. Mvyur, Helv. chim. Acta 7, 19 (1924).
Angew. C'hem. itrtcrtitrf. Edit. 1 Vol. 2 (1963)
1 No. 10
[18]. It may be assumed that the other olefins listed in
Table 3 also react with the dimethylketenederived from
the acylal in the same manner as isobutylene does, i.e.
that the carbonyl group of dimethylketene adds onto
the carbon atom of the double bond which bears the
greater number of hydrogens.
IV. Experimental
Preparation of the Dimcfhylketenacylal of Dimethylmalonic Acid ( I )
A mixture of 528 g (4 moles) of dimethylmalonic acid and
1632 g (16 moles) of acetic anhydride is heated slowly to
boiling at a pressure of about 10 mm Hg. The acetic acid formed is removed continuously over an efficient fractionating
column. The removal of the thcoretical amount of acetic
acid from the reaction mixture is followed by a spontaneous
evolution of Con, as indicatcd by a rise in pressure. The
evolution of CO2 is allowed to continue at atmospheric
pressure (vented apparatus) and is complete within a few
hours. Removal of the excess acetic anhydride by vacuum
distillation affords 300 g (80 %) of a crystalline residue of the
dimethylketenacylal; m. p. 80 'C (from petroleum ether).
Reaction of' (1) with Alcohols
A mixture of 16 g (0.2 mole) of t-butanol and 18.4g (0.1mole)
of the dimethylketenacylal ( I ) is refluxed with 100 mg of
K2CO3 until C02 is no longer given off. Distillation of the
of t-butyl isobutyrate,
reaction product affords 27.5 g (75
b.p. 127OC.
x)
Reaction of ( I ) with Secondary Amines
Piperidine (42.5 g = 0.5 mole) is added dropwise with stirring
to 46 g (0.25 mole) of the dimethylketenacylal (I). The
reaction mixture liquefies and CO2 is evolved. The reaction is
complete when no more C02 is given off. Distillation affords
72.5 g (91 %) of isobutyric pipcridide, b.p. 115"C/lS mm.
Reaction of ( I ) with Gaseous Olefins
A 500-ml autoclave equipped with agitator is charged with
92 g (0.5 mole) of the dimethylketenacylal (I), 100 ml of
toluene, 500 mg of KzCO3, and 210 g of propylene. The
mixture is heated slowly to 130°C. After eight h o w , distillation of the contents of the autoclave affords 82 g of
2,2,3-trimethylcyclobutanone(72 yield based on the dimethylketenacylal); b. p. 138 "C.
Reaction of ( I ) with Liquid Olefins
A mixture of 9.2 g (0.05 mole) of the dimethylketenacylal (I),
50 g of 1-decene, and 100 mg of potassium carbonate is
heated slowly to 130°C. The carbon dioxide formed is
removed through a reflux condenser. The reaction is complete
after 6 hours. Distillation of the mixture in vucuo affords
14 g of 2,2-dimethyl-3-octylcyclohu~anone
(67 % yield based
on the dimethylketenacylal); b. p. 88 T / l mm Hg.
Received, June 4th, 1963
[A 311/109 IB]
German version: Angew. Chem. 75, 841 (1963)
[I81 H. E. Buumgurten, J. Amcr. chcm. SOC.75,979 (1953j.
Preparation of Carbon Tetrachloride from Phosgene
BY PROF. DR. 0. GLEMSER
IN COLLABORATION WITH DR. J. SCHRaDER, DR. K. KLEINE-WEISCHEDE, DR. BORIS MEYER,
DR. G. PEUSCHEL, R. FLUGEL, AND DR. D. VELDE
ANORGANISCH-CHEMISCHES INSTITUT DER UNIVERSITAT GOTTINGEN (GERMANY)
Dedicated to Prof. Dr. Karl Winnacker on the occcision of his 60th birthday
Carbon tetrachloride can be prepared from phosgene at 300-450 "C.The catalysts for the
waaction are transition metals of Croups V to VIII deposited on activated charcoal as
carrier. Carbon monoxide and chlorine may he used as starting materials instead of phosgww.
Although at one time carbon tetrachloride was made
principally from carbon disulfide and chlorine, by far the
largest quantity is now made by chlorination of methane.
In the latter process
CHr
+ 4Clz + CC4 -I-4HCI
(1)
four moles of hydrogen chloride are formed for each
mole of carbon tetrachloride; thus, only half of the
chlorine charge is converted into carbon tetrachloride.
For numerous reasons it was desirable to achieve a synthesis of carbon tetrachloride in which no hydrogen
chloride is formed or which converts the chlorine quanAngew. Chem. intcrnnt. Edit. / V d . 2 (1963) I No. 10
titatively into carbon tetrachloride. These conditions are
met by the decomposition of phosgene into carbon tetrachloride and carbori dioxide:
2 c:oc12 ;! cc14 c coz
(2)
Stock and co-workers [1-3] and Fink and Bonilla [4]
found this reaction to be thermodynamically possible.
[I.]
A. Stock and W. Wusrrow, Z.anorg,allg.Chem.I47,245(1925).
[2]A . Stock, W . Wustrow, H. Lux, and H . A'umser, 2.anorg. allg.
Chem. 195, 140 (1931).
[3]A.Stock, H.Lux, and W. Wusfrow, Z. anorg. allg. Chem. 195,
149 (1931).
[4]C. G.Fink and C. F.Bonilla, J. physic. Chem. 37, 1135 (1933).
613
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