Nucleophilic addition to acetylenes in superbasic catalytic systems: X. Catalytic effect of alkali metal hydroxides in the vinylation of 1-heptanol

Article abstract of DOI:10.1023/A:1012462113437

- The catalytic activity of alkali metal hydroxides in base-catalyzed addition of 1-heptanol to acetylene depends on the alkali metal nature and degree of hydration of its hydroxide. In a closed system, the catalytic activity of alkali metal hydroxides decreases in the series 2KOH·H₂O > RbOH·H₂O > CsOH·H₂O > NaOH. The corresponding series for a flow system is as follows: RbOH·H₂O > CsOH·H₂O > 2KOH·H₂O > NaON > KOH·H₂O. The difference is explained by participation of the catalyst in side reactions with both 1-heptanol and acetylene. Addition of dimethyl sulfoxide to the catalytic system accelerates the vinylation process.

Full text of DOI:10.1023/A:1012462113437

Russian Journal of Organic Chemistry, Vol. 37, No. 7, 2001, pp. 940 945. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 7, 2001,
pp. 993 998.
Original Russian Text Copyright
2001 by Parshina, Oparina, Gorelova, Preiss, Henkelmann, Trofimov.
Nucleophilic Addition to Acetylenes in Superbasic Catalytic
Systems: X.* Catalytic Effect of Alkali Metal Hydroxides
in the Vinylation of 1-Heptanol
1
1
1
2
L. N. Parshina , L. A. Oparina , O. V. Gorelova , T. Preiss ,
2
1
J. Henkelmann , and B. A. Trofimov
1
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: bat@irioch.irk.ru
2
BASF Actiengesellschaft, Ammonia Laboratory, Ludwigshafen, Germany
Received July 11, 2000
Abstract The catalytic activity of alkali metal hydroxides in base-catalyzed addition of 1-heptanol to
acetylene depends on the alkali metal nature and degree of hydration of its hydroxide. In a closed system,
the catalytic activity of alkali metal hydroxides decreases in the series 2KOH H2O > RbOH H2O >
CsOH H2O > NaOH. The corresponding series for a flow system is as follows: RbOH H2O > CsOH H2O >
2KOH H2O > NaON > KOH H2O. The difference is explained by participation of the catalyst in side
reactions with both 1-heptanol and acetylene. Addition of dimethyl sulfoxide to the catalytic system
accelerates the vinylation process.
Direct vinylation, i.e., addition of hydroxy com-
pounds to acetylene in the presence of base catalysts,
was thoroughly studied by Favorskii [2], Shostakov-
skii [3], and Reppe [4]. This reaction can be regarded
as the most universal method for preparation of vinyl
ethers. The procedure is convenient for large-scale
applications due to accessibility of starting com-
pounds, high yields of the target products, and single-
stage process. Syntheses of vinyl ethers and numerous
studies of their structure and reactivity have been
reviewed in a number of publications [5 9].
insufficiently studied. Such processes are polymeriza-
tion of acetylene [7], formation of acetals [5, 7],
evolution of hydrogen, formation of carboxylic acid
salts, [5 7, 12], etc. The formation of alkali metal
carboxylates was often explained by the presence
of water [6, 7] which is capable of reacting with
acetylene to form acetates and hydrogen [14 16];
however, this does not explain formation of other
salts. Moreover, inhibitory effect of water on the
vinylation is known [6, 7, 13, 17]; the mechanism of
water effect was interpreted in terms of decrease in the
basicity of the system [6, 7] or (what is equivalent)
decrease in the concentration of RO [13].
Despite vast information on the vinylation process,
studies on its kinetic parameters are likely to be
limited to those published in [9 13]. Among these,
only Otsuka et al. [13] examined the nature of metal
cation in the alkoxide on the rate of vinylation. Using
isobutyl alcohol as an example, it was shown that the
rate of vinylation decreases in the following series of
The present communication gives the results ob-
tained by studying the effect of alkaline catalyst and
water on the rate of vinylation of 1-heptanol with
acetylene under atmospheric pressure; specific features
of the main and side processes are discussed.
cations: K+ (1.00) > Rb+ (0.83) > Na+ (0.76) > Li+
The choice of 1-heptanol as model substrate was
dictated by its high boiling point and high boiling
point of the vinylation product, heptyl vinyl ether (I),
which make it possible to perform the reaction in
the temperature range from 150 to 166 C. The process
was performed in both closed and flow systems under
+
(0.10) > C6H5CH2N(CH3)3 (0.00).
Side processes accompanying vinilation of alcohols
and hydroxy compounds as a whole also remain
____________
*
For communication IX, see [1].
1070-4280/01/3707-0940$25.00 2001 MAIK Nauka/Interperiodica

NUCLEOPHILIC ADDITION TO ACETYLENES IN SUPERBASIC CATALYTIC SYSTEMS: X.
941
an acetylene pressure equal to atmospheric. In the
closed system we measured the rate of absorption of
acetylene by 1-heptanol in the presence of 10 mol %
of commercial alkali metal hydroxides: NaOH,
2KOH H2O (according to the titration data, potassium
hydroxide contained 15% of water, which corresponds
exactly to the formula 2KOH H2O), RbOH H2O,
and CsOH H2O; lithium hydroxide did not catalyze
vinylation of 1-heptanol with acetylene even under
pressure.
Fig. 1. Absorption of acetylene in the vinylation of
1-heptanol in the presence of alkali metal hydroxides
(closed system, 164 166 C): (1) NaOH, (2) CsOH H2O,
(3) RbOH H2O, (4) 2KOH H2O.
In the presence of the above listed alkali metal
hydroxides absorption of acetylene begins only at
about 160 C. Figure 1 shows acetylene absorption
curves at 164 166 C. It is seen that in the series of
hydrated hydroxides 2KOH H2O, RbOH H2O, and
CsOH H2O, the rate of acetylene absorption decreases
as the size of the cation increases. This may be due
to the presence of an additional amount of water
which is introduced into the system with the mono-
hydrates RbOH H2O and CsOH H2O. The presence
of water reduces not only the basicity of the system
[6, 7] but also partial pressure of acetylene. Sodium
hydroxide is the least active catalyst despite it con-
tains no hydrate water.
In all cases the yield of ether I determined by GLC
was lower than that calculated from the amount of
absorbed acetylene, and the conversion of 1-heptanol
(without taking into account possible formation of
alkoxide) is greater than the yield of vinyl ether I
(Table 1). These data indicate the occurrence of side
reactions involving acetylene and 1-heptanol. On the
other hand, titration of the final reaction mixtures
(after dilution with water) showed that the catalyst
undergoes some transformations which give rise to
salts of organic acids (Table 1). Insofar as water is
always present in the system (it is liberated upon
formation of alkoxides), such a reaction may be
the known formation of acetates from alkali, water,
and acetylene [14 16]:
Assuming that the difference between the conver-
sion of 1-heptanol and the yield of I is the result of
formation of alkali metal heptanoates, we calculated
the conversion of alkali into heptanoate, which turned
out to be 6 7% (Table 1). The difference between the
conversion of alkali into all salts and heptanoate is
its conversion into acetate. Since acetates are formed
with participation of acetylene, the required amount
of acetylene can be calculated from the amount of
acetates. Table 1 gives the conversions of acetylene
into acetates. The overall conversion of acetylene
into acetate and vinyl ether I is complete only when
CsOH H2O and RbOH H2O are used as catalyst.
With 2KOH H2O and NaOH, the conversion is less
than 100%, suggesting the occurrence of other side
processes. We observed no polymerization of ace-
tylene (with formation of a dark insoluble powder
of polyacetylene); therefore, we can presume that
acetylene is consumed for the formation of acetalde-
hyde and polymers derived therefrom:
We can conclude that the vinylation of alcohols
with acetylene is accompanied by side formation of
salts via both Dumas Stass reaction and reaction of
acetylene with alkali and water. The two processes
release hydrogen which, together with water vapor,
reduces partial pressure of acetylene in the gas phase.
We can thus explain the higher rate of acetylene
Another possible process is the Dumas Stass
reaction leading to alkali metal heptanoates from
1-heptanol and alkali [18]:
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 7 2001

942
PARSHINA et al.
Table 1. Vinylation of 1-heptanol with acetylene (atmospheric pressure, closed system, 10 mol % of alkali metal
hydroxide, 164 166 C)
Yield Conversion Absorption Conversion of acetylene, %
Conversion of catalyst, %
Time,
h
Catalyst
of I,a
of
of acetylene,
mmol
%
heptanol, %
into I
into MeCO2M into MeCO2M into C6H13CO2M
NaOH
2KOH H2O 3.3
RbOH H2O
CsOH H2O
5.0
3.0
4.9
5.7
4.2
3.7
5.5
6.3
4.9
4.1
8.4
6.5
5.8
73
58
88
72
15
15
17
28
6
13
11
16
7
6
6
7
4.2
7.0
a
Yield of ether I calculated on the 1-heptanol taken.
absorption in the catalysis by 2KOH H2O not only
by the lower concentration of water in the liquid
and gas phases but also by the lower activity of potas-
sium hydroxide, as compared to cesium and rubidium
hydroxides, in side salt formation reactions accom-
panied by evolution of hydrogen. Presumably, the
higher rate of acetylene absorption in the presence of
rubidium hydroxide compared to cesium hydroxide,
fast reduction of the rate of acetylene absorption in
the presence of CsOH H2O, and its slow reduction in
the presence of sodium hydroxide can be interpreted
in a similar way.
The vinylation of 1-heptanol in a flow system was
carried out by passing acetylene at a rate of 2 l/h
through a solution of alkali metal hydroxide in
1-heptanol, heated to 164 166 C. Unlike the closed
system, partial pressure of acetylene in a flow system
does not depend on the amount of liberated hydrogen,
and the order of the kinetic curves changes (Fig. 2).
The activity of alkali metal hydroxides falls in the
series RbOH H2O > CsOH H2O > 2KOH H2O >
NaOH > KOH H2O.
Despite lower concentration of water, 2KOH H2O
is less active in the vinylation than cesium and
rubidium hydroxide monohydrates. On addition of
water to an amount corresponding to the monohydrate,
the rate of vinylation sharply decreases and becomes
even lower than the rate of vinylation in the presence
of NaOH. Under these conditions, rubidium hydroxide
monohydrate turned out to be more active than cesium
hydroxide monohydrate (Fig. 2), which is consistent
with the data obtained in the vinylation of 1-heptanol
in the closed system (Table 1; cf. yields of I in the
presence of RbOH H2O and CsOH H2O).
The yield of ether I and the conversion of the
substrate into products (except for alkoxides) in the
presence of each alkali metal hydroxide were calcu-
lated from the concentrations of I and 1-heptanol in
the reaction mixture after passing acetylene over
a period of 7 h. The conversion of MOH into the
corresponding metal carboxylates was determined by
titration of the reaction mixtures strongly diluted
with water. The conversions of alkali into heptanoate
and acetate were then calculated separately. The
results are collected in Table 2. It is seen that the main
process responsible for consumption of alkali is
formation of acetates. It was surprising that the yields
of ether I in the flow system were lower than in the
closed system. A possible reason is faster consump-
tion of alkali (cf. Tables 1 and 2) due to unlimited
supply of acetylene into the mixture and hence faster
formation of acetates.
It is known [17, 19 23] that addition of nucleo-
philes to acetylene is strongly accelerated in catalytic
media including highly basic reagents. The most
convenient and universal are systems like alkali metal
hydroxide polar aprotic solvent (such as DMSO,
HMPA, etc.). Higher reaction rate makes it possible
Fig. 2. Change of the concentration of ether I with time
in the vinylation of 1-heptanol with acetylene in the pres-
ence of alkali metal hydroxides (flow system, 164 166 C):
(1) KOH H2O, (2) NaOH, (3) 2KOH H2O, (4) CsOH
H2O, (5) RbOH H2O.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 7 2001

NUCLEOPHILIC ADDITION TO ACETYLENES IN SUPERBASIC CATALYTIC SYSTEMS: X.
943
Table 2. Vinylation of 1-heptanol with acetylene (atmospheric pressure, flow system, 10 mol % of alkali metal
hydroxide, 164 166 C, 7 h)
Conversion of catalyst, %
Conversion
Catalyst
Yield of ether I, %
of heptanol, %
into MeCO2M
into C6H13CO2M
NaOH
2.1
2.5
0.4
3.9
3.4
2.6
4.2
1.0
3.9
3.8
5
17
6
16
9
2KOH H2O
KOH H2O
RbOH H2O
CsOH H2O
24
29
28
0
4
to perform the process under milder conditions. Also,
we can expect that lowering the temperature will slow
down side processes which accompany the vinylation
and deactivate the catalyst.
chemically pure grade; and KOH was of analytical
grade (it contained 15% of hydrate water, according
to the titration data). 1-Heptanol and DMSO were
distilled prior to use. Commercial acetylene (from
gas cylinder) was purified as described in [25].
Taking into account the high activity of cesium
hydroxide in side formation of metal carboxylates,
we brought 1-heptanol into reaction with acetylene
under atmospheric pressure in the presence of com-
mercial cesium hydroxide. The latter was taken in
an amount of 20 mol % with respect to 1-heptanol.
The amount of dimethyl sulfoxide ensured formation
of a 1 M solution of 1-heptanol, in keeping with
the conditions developed in [24] for vinylation of
alcohols. Acetylene was passed through a solution
at a flow rate of about 2 l/h.
Under these conditions (temperature 50 C) the
reaction was slow but nevertheless faster than the
vinylation of 1-heptanol in the presence of 10 mol %
of CsOH H2O at 165 C (Fig. 3). Unfortunately, even
under such mild conditions the conversion of cesium
hydroxide into cesium carboxylates was greater than
20%, according to the potentiometric titration data.
Vinylation of 1-heptanol with acetylene under
atmospheric pressure in a closed system. The sys-
tem was a 50-ml three-necked round-bottomed flask
equipped with a thermometer, a stopper for acetylene
outlet (when purging the system), and an acetylene
burette which was connected to a vessel filled with
a saturated solution of magnesium sulfate. Acetylene
from the burette passed through a Tishchenko bottle
filled with pelleted KOH into the reaction flask
through a gas-inlet tube whose end was above the
surface of the reaction mixture. The flask was heated
on an oil bath, and the mixture was stirred using
a magnetic stirrer.
The flask was charged with 11.6 g (0.1 mol) of
1-heptanol and 0.01 mol of alkali metal hydroxide, the
EXPERIMENTAL
The reaction mixtures were analyzed by GLC using
an LKhM-80 chromatograph; thermal conductivity
detector, carrier gas helium (flow rate 2 l/h), 3000
3-mm column, stationary phase 1% of polyethylene
glycol 20000 on NaCl (0.16 0.25 mm), oven tem-
perature 100 C. Alkali metal hydroxides, heptanoates,
and acetates were quantitated by potentiometric titra-
tion of dilute aqueous solutions. The titration was per-
formed at 20 C using an EV-74 universal ionometer
equipped with glass and silver chloride electrodes;
0.1 N HClO4 was used as titrant.
Fig. 3. Change of the yield of ether I with time in the
vinylation of 1-heptanol with acetylene in the presence of
cesium hydroxide monohydrate without a solvent and in
DMSO (flow system): (1) CsOH H2O, 165 C; (2) CsOH
H2O DMSO, 50 C.
1-Heptanol, RbOH H2O, and CsOH H2O were
of pure grade; DMSO, LiOH, and NaOH were of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 7 2001

944
PARSHINA et al.
system was purged with acetylene, and the mixture
was slowly heated to a required temperature (alkali
metal hydroxide dissolved fairly rapidly). The absorp-
tion of acetylene was monitored following the level
of the magnesium sulfate solution transferred to the
burette as acetylene was consumed. The resulting
acetylene absorption curves are shown in Fig. 1.
Potentiometric titration of the reaction mixture (after
dilution with water) revealed a 22% conversion of
cesium hydroxide into the corresponding carboxylates.
REFERENCES
1. Parshina, L.N., Sokolyanskaya, L.V., Nosyre-
va, V.V., Scotheim, T., Zefirov, N.S., and Trofi-
mov, B.A., Russ. J. Org. Chem., 1999, vol. 35, no. 2,
pp. 202 206.
When the reaction was complete, the mixture was
analyzed by GLC using 0.5 g of tridecane as internal
standard. The yield of ether I was calculated from
the GLC data. The mixture was then diluted with
water to a volume of 500 ml (aqueous phase) under
thorough stirring. The organic layer was separated,
and the concentrations of alkali metal hydroxide and
carboxylates in the aqueous phase were determined
by titration. The results are given in Table 1.
2. Akademik Aleksei Evgrafovich Favorskii. Izbrannye
trudy (Academician Aleksei Evgrafovich Favorskii.
Selected Papers), Moscow: Akad. Nauk SSSR, 1961.
3. Shostakovskii, M.F., Prostye vinilovye efiry (Vinyl
Ethers), Moscow: Akad. Nauk SSSR, 1952.
4. Reppe, W., Justus Liebigs Ann. Chem., 1956,
vol. 601, pp. 81 138.
Vinylation of 1-heptanol with acetylene under
atmospheric pressure in a flow system. A 50-ml
flask equipped with a thermometer, reflux condenser,
and gas-inlet tube (immersed into the liquid) was
charged with 11.6 g (0.1 mol) of 1-heptanol, 0.01 mol
of alkali metal hydroxide, and 0.5 g (precisely
weighed) of tridecane as internal standard for GLC
analysis. The mixture was heated on an oil bath under
stirring with a magnetic stirrer. Alkali metal hy-
droxides rapidly dissolved on heating. The mixture
was heated to 164 166 C, and acetylene was passed
at a flow rate of about 2 l/h. Samples of the mixture
were withdrawn every 30 min using a long pipette and
were analyzed by GLC. The results (kinetic curves for
formation of vinyl ether I) are shown in Fig. 2. A con-
siderable dispersion of points is explained by the low
concentration of the product, which gives rise to
large errors in the treatment of chromatographic data.
The concentrations of alkali metal hydroxide, acetate,
and heptanoate were determined by potentiometric
titration as described above for the closed system
(Table 2).
5. Kopenhaver, J. and Bigelou, M., The Chemistry of
Acetylene and Related Compounds, Bergmann, E.D.,
Ed., New York: Intersci., 1948. Translated under the
title Khimiya atsetilena, Moscow: Inostrannaya Lite-
ratura, 1954, pp. 174 239.
6. Shostakovskii, M.F., Trofimov, B.A., Atavin, A.S.,
and Lavrov, V.I., Usp. Khim., 1968, vol. 37,
pp. 2070 2093.
7. Trofimov, B.A., Geteroatomnye proizvodnye atseti-
lena. Novye polifunktsional’nye monomery, reagenty
i poluprodukty (Heteroatomic Acetylene Derivatives.
New Polyfunctional Monomers, Reagents, and Inter-
mediate Products), Moscow: Nauka, 1981.
8. Tedeschi, R.J., Encyclopedia of Physical Science
and Technology, New York: Academic, 1992, vol. 1,
pp. 27 65.
9. Miller, S.A., Acetylene, Its Properties, Manufacture,
and Uses, London: Benn, 1966, vol. 2, pp. 198 245.
10. Miller, S.I. and Shkapenko, G., J. Am. Chem. Soc.,
1955, vol. 77, no. 19, pp. 5038 5041.
11. Nagasawa, F. and Matsuzawa, K., J. Chem. Soc. Jpn.,
Ind. Chem. Sec., 1958, vol. 61, no. 1, pp. 28 33.
12. Otsuka, S., Matsui, Y., and Murahashi, S., Nippon
Kagaku Zasshi, 1956, vol. 77, no. 5, pp. 766 773.
Vinylation of 1-heptanol with acetylene under
atmospheric pressure in a flow system in the pres-
ence of CsOH
H2O DMSO. A 100-ml flask equip-
13. Otsuka, S., Matsui, Y., and Murahashi, S., Nippon
Kagaku Zasshi, 1959, vol. 80, no. 10, pp. 1157
1160.
ped with a thermometer, reflux condenser, and gas-
inlet tube (immersed into the liquid) was charged
with 5.8 g (0.05 mol) of 1-heptanol, 1.7 g (0.01 mol)
of CsOH H2O, and 50 ml of DMSO (the latter was
also used as internal standard for GLC analysis).
Acetylene was passed at a rate of 2 l/h over a period
of 3 h through the mixture heated to 50 C; the mix-
ture was analyzed by GLC as described above. The
results are given in Fig. 3. The yield of ether I
calculated from the GLC data was 0.3 g (4.2%).
14. US Patent no. 1866328, 1932; Chem. Abstr., 1932,
vol. 26, no. 16, p. 4345.
15. US Patent no. 1866329, 1932; Chem. Abstr., 1932,
vol. 26, no. 16, p. 4345.
16. US Patent no. 1866430, 1932; Chem. Abstr., 1932,
vol. 26, no. 16, p. 4345.
17. Steinborn, D., Mosinski, H., and Rosenstock, T.,
J. Organomet. Chem., 1991, vol. 414, pp. 45 50.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 7 2001

NUCLEOPHILIC ADDITION TO ACETYLENES IN SUPERBASIC CATALYTIC SYSTEMS: X.
945
18. Widon, B., Technique of Organic Chemistry, Weiss-
berger, A., Ed., New York: Intersci., 1965, 3rd ed.,
vol. 11, part 2. Translated under the title Metody
organicheskoi khimii. Ustanovlenie struktury organi-
cheskikh soedinenii fizicheskimi i khimicheskimi
metodami, Moscow: Khimiya, 1967, vol. XI, part II,
pp. 234 290.
22. Trofimov, B.A., Russ. J. Org. Chem., 1995, vol. 31,
no. 9, pp. 1233 1252.
23. Steinborn, D., Rosenstock, T., and Sieler, J., J. Prakt.
Chem., 1996, vol. 338, no. 3, pp. 264 269.
24. Trofimov, B.A., Oparina, L.A., Lavrov, V.I., and
Parshina, L.N., Russ. J. Org. Chem., 1995, vol. 31,
no. 5, pp. 597 600.
19. Trofimov, B.A., Usp. Khim., 1981, vol. 50, pp. 248
272.
25. Miller, S.A., Acetylene, Its Properties, Manufacture,
and Uses, London: Benn, 1966, vol. 1. Translated
under the title Atsetilen, ego svoistva, poluchenie
i primenenie, Leningrad: Khimiya, 1969, vol. 1,
pp. 308 310.
20. Trofimov, B.A., Z. Chem., 1986, vol. 26, no. 2,
pp. 41 49.
21. Trofimov, B.A., Zh. Org. Khim., 1986, vol. 22, no. 9,
pp. 1991 2006.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 7 2001