Process for producing pyrrolidone derivative

Disclosed herein is a process for producing a pyrrolidone derivative represent by the general formula (I): ##STR1## wherein R is an organic residue obtained by removing hydroxy radical from a C.sub.1-10 primary alcohol, C.sub.1-10 secondary alcohol or derivative thereof, comprising (1) reacting 2-pyrrolidone with acetaldehyde in the presence of a catalyst, thereby obtaining N-(.alpha.-hydroxyethyl)pyrrolidone, and (2) reacting the thus obtained N-(.alpha.-hydroxyethyl)pyrrolidone with a primary alcohol, a secondary alcohol or a derivative thereof in the presence of an acidic catalyst to obtain the pyrrolidone derivative.

BACKGROUND OF THE INVENTION 
The present invention relates to a process for producing a pyrrolidone 
derivative represent by the general formula (I): 
##STR2## 
wherein R is an organic residue obtained by removing hydroxy radical from 
a C.sub.1-10 primary alcohol, C.sub.1-10 secondary alcohol or derivative 
thereof, by reacting acetaldehyde with 2-pyrrolidone, thereby containing 
N-(.alpha.-hydroxyethyl)pyrrolidone and reacting with a primary alcohol, a 
secondary alcohol or a derivative thereof with the thus obtained 
N-(.alpha.-hydroxyethyl)pyrrolidone to obtain the object product, the 
pyrrolidone derivative represented by the formula (I). 
N-(.alpha.-hydroxyethyl)pyrrolidone and N-(.alpha.-alkoxyethyl)pyrrolidone 
are the useful starting materials for the synthesis of N-vinylpyrrolidone 
along the following reaction formula. 
##STR3## 
As a process for producing N-(.alpha.-alkoxyethyl)pyrrolidone, 
(1) a process for producing N-(.alpha.-ethoxyethyl)pyrrolidone by reacting 
diethylacetal with 2-pyrrolidone (yield: 34%) (refer to Ber. Vol. 
99,2128,1965), and 
(2) a process for producing N-(.alpha.-methoxyethyl)pyrrolidone by reacting 
.alpha.-chloroethyl methyl ether with 2-pyrrolidone (yield: 78%) (refer to 
Japanese Patent Application Laid-Open No. 56-75464 (1971)) have been 
hitherto known. 
However, these processes are not industrially satisfactory, because the 
yield of the process (1) is low and the industrial utilization of the 
starting material of the process (2) is difficult. 
On the other hand, a process for producing N-(.alpha.-hydroxyethyl)cyclic 
amide has been known. For instance, in Japanese Patent Publication No. 
45-14283(1970), a process wherein acetaldehyde is reacted with a secondary 
cyclic amide by liquid-liquid contact in the presence of an acidic 
catalyst or basic catalyst, thereby containing 
N-(.alpha.-hydroxyethyl)cyclic amide and the thus obtained 
N-(.alpha.-hydroxyethyl)cyclic amide is subjected to thermal decomposition 
to obtain N-vinylamide, has been disclosed. 
However, there is a problem in the process that the yield of the thus 
produced N-(.alpha.-hydroxyethyl)pyrrolidone is low. For instance, Example 
3 of the Japanese Patent Publication only discloses the yield of the final 
product, N-vinylpyrrolidone, however, even in the case where the rate of 
conversion of N-(.alpha.-hydroxyethyl)pyrrolidone to N-vinylpyrrolidone by 
thermal decomposition is assumed to be 100%, there is a problem that the 
yield of N-(.alpha.-hydroxyethyl)pyrrolidone is only about 50%. 
As a result of the present inventors' studies concerning a process for 
producing a pyrrolidone derivative useful for the synthesis of 
N-vinylpyrrolidone in a higher yield than that of the hitherto-known 
methods, the present inventors have found that an object of the present 
invention is easily achieved by (1) reacting acetaldehyde with 
2-pyrrolidone in the presence of a catalyst (hereinafter referred to as 
"the first step"), thereby obtaining N-(.alpha.-hydroxyethyl)pyrrolidone 
and (2) reacting the thus obtained N-(.alpha.-hydroxyethyl)pyrrolidone 
with a primary alcohol, a secondary alcohol or a derivative thereof in the 
presence of a acidic catalyst (hereinafter referred to as "the second 
step"), and the present invention has been attained based on the 
above-mentioned finding. 
SUMMARY OF THE INVENTION 
In an aspect of the present invention, there is provided a process for 
producing a pyrrolidone derivative represented by the general formula (I): 
##STR4## 
wherein R is an organic residue obtained by removing hydroxy radical from 
a C.sub.1-10 primary alcohol, C.sub.1-10 secondary alcohol or derivative 
thereof, comprising: 
(1) reacting 2-pyrrolidone with acetaldehyde in the presence of a catalyst 
which is at least one member selected from the group consisting of 
potassium carbonate, sodium carbonate, potassium phosphate, sodium 
phosphate, potassium pyrophosphate, sodium pyrophosphate, potassium 
silicate and sodium silicate in an amount of 0.0001 to 10 mol % of the 
catalyst per mole of 2-pyrrolidone, thereby obtaining 
N-(.alpha.-hydroxyethyl)pyrrolidone at a temperature in the range of 
-10.degree. to 60.degree. C.; and 
(2) reacting the thus obtained N-(.alpha.-hydroxyethyl)pyrrolidone with a 
C.sub.1-10 primary alcohol, a C.sub.1-10 secondary alcohol or a derivative 
thereof in the presence of an acidic catalyst selected from the group 
consisting of an inorganic acid, sulfamic acid, methanesulfonic acid, 
ethanesulfonic acid, p-toluenesulfonic acid and an acidic ion-exchange 
resin used in an amount of 0.001 to 10 mol % of the acidic catalyst per 
mole of N-(.alpha.-hydroxyethyl)pyrrolidone at a temperature in the range 
of -10.degree. to 100.degree. C. 
DETAILED DESCRIPTION OF THE INVENTION 
According to the process of the present invention (hereinafter referred to 
as "the present process"), 2-pyrrolidone is reacted with acetaldehyde in 
the presence of a catalyst to obtain N-(.alpha.-hydroxyethyl)pyrrolidone. 
The reaction may be carried out in any conventional reaction vessel 
equipped with a stirrer by introducing 2-pyrrolidone into the reaction 
vessel, and then supplying acetaldehyde which is in the gaseous state or 
liquid state, preferably the gaseous state, into the vessel continuously. 
Although the reaction is ordinarily carried out batchwise, it is possible 
to carry out the reaction continuously. 
The catalyst used in the first step of the present process is a weakly 
basic salt comprising a strong base and a weak acid showing a pKa of 4 to 
15. The pKa is a value of an aqueous solution of the acid of a 
concentration of 0.01 mol/liter at 25.degree. C. As such a weakly basic 
salt, for instance, a salt of a strong base such as hydroxides of lithium, 
sodium and potassium with a weak acid such as organic acids, phenols, 
sulfurous acid, phosphorous acid, phosphinic acid, pyrophospohoric acid, 
phosphoric acid, carbonic acid, boric acid, orthosilicic acid, metasilicic 
acid, etc. may be used. Of the salts, the particularly preferable salts 
are potassium carbonate, sodium carbonate, potassium phosphate, sodium 
phosphate, potassium pyrophosphate, sodium pyrophosphate, potassium 
orthosilicate and sodium orthosilicate. 
The ratio of the amount of the catalyst used in the first step of the 
present process based on the amount of 2-pyrrolidone is generally selected 
from the range of 0.0001 to 10 mol %, and the preferable range depends on 
the state of supplying acetaldehyde as a starting material to the reaction 
system. Namely, in the case of supplying acetaldehyde in a gaseous state 
(in the manner of supplying acetaldehyde in the gaseous state, 
acetaldehyde is used after removing acetic acid present in acetaldehyde, 
as a decomposition material), the ratio thereof is preferably selected 
from the range of 0.001 to 1 mol %, more preferably from 0.01 to 0.5 mol 
%. 
On the other hand, in the case of supplying acetaldehyde containing acetic 
acid in the liquid state, it is preferable to carry out the introduction 
of acetaldehyde in consideration of the coexistence of acetic acid as 
follows. 
Namely, while assuming the amount of acetic acid in acetaldehyde to the 
amount of 2-pyrrolidone to be X mol %, the amount of the catalyst to the 
amount of 2-poyrrolidone is selected from the range of (X+0.001) to (X+2) 
mol %, preferably (X+0.01) to (X+2) mol %. In the case where the amount of 
the catalyst to the amount of 2-pyrrolidone is below (X+0.001) mol %, the 
reaction rate is extremely low, and on the other hand, in the case where 
the amount is over (X+2) mol %, the conversion ratio of 2-pyrrolidone is 
low. 
The reaction is carried out at a temperature selected from the range of 
-10.degree. to 60.degree. C., preferably 0.degree. to 50.degree. C. In the 
case where the reaction is carried out at a temperature of over 60.degree. 
C., both the decomposition of the thus produced 
N-(.alpha.-hydroxyethyl)pyrrolidone and the condensation of acetaldehyde 
are caused, and on the other hand, in the case of carrying out the 
reaction at a temperature of below -10.degree. C., the reaction rate is 
extremely slow. 
Although the reaction between 2-pyrrolidone and acetaldehyde can be carried 
out in the presence or absence of a solvent, it is preferable to carry out 
the reaction in the presence of a solvent dissolving 2-pyrrolidone in the 
case where the reaction is carried out at a temperature of below the 
melting point of 2-pyrrolidone(25.degree. C.). As the solvent, water, 
alcohols such as methanol, ethanol, etc., aromatic hydrocarbons such as 
benzene, toluene, xylene, etc., aliphatic hydrocarbons such as n-hexane, 
etc., alicyclic hydrocarbons such as cyclohexane, etc., ethers such as 
diethyl ether, tetrahydrofuran, etc. and esters such as ethyl acetate, 
etc. may be exemplified. The amount of the solvent used in the first step 
of the present process is suitably selected from the range of 0.01 to 5 
times by weight of the amount of 2-pyrrolidone. 
The molar ratio of acetaldehyde to 2-pyrrolidone is ordinarily in the range 
of 0.7 to 2.0, preferably 0.9 to 1.6. In the case where the molar ratio is 
below 0.7, although the each selectivity of 
N-(.alpha.-hydroxyethyl)pyrrolidone based on 2-pyrrolidone and an 
acetaldehyde are high, the conversion ratio of 2-pyrrolidone is low. On 
the other hand, in the case where the molar ratio is over 2.0, although 
the conversion ratio of 2-pyrrolidone is high, the selectivity of 
N-(.alpha.-hydroxyethyl)pyrrolidone based on acetaldehyde is low. 
In addition, the yield in the present process can be raised by 
precipitating N-(.alpha.-hydroxyethyl)pyrrolidone which has been formed 
during the reaction and thereafter continuing the reaction. The 
precipitation of N-(.alpha.-hydroxyethyl)pyrrolidone is ordinarily carried 
out in the same reaction vessel in which the reaction between 
2-pyrrolidone and acetaldehyde has been carried out, however, the 
precipitation may be carried out in a different reaction vessel. In the 
case of carrying out the operation in the same reaction vessel, (i) the 
reaction system is cooled to a temperature of -20.degree. to 25.degree. 
C., preferably 0.degree. to 10.degree. C. when the conversion ratio of 
2-pyrrolidone becomes 50 to 97 mol %, preferably 60 to 97 mol % and more 
preferably 70 to 97 mol %, (ii) a small amount of 
N-(.alpha.-hydroxyethyl)pyrrolidone, as the crystal nucleus, is added to 
the reaction system or (iii) the cooling and the addition are carried out 
simultaneously in combination, thereby precipitating the crystals of 
N-(.alpha.-hydroxyethyl)pyrrolidone. 
Namely, in the case where the conversion ratio of 2-pyrrolidone is below 60 
mol %, it is difficult to precipitate the crystals, and on the other hand, 
in the case where the conversion ratio of over 97 mol %, although the 
precipitation of the crystals is easily effected, it is not profitable 
because it is necessary to use a large excess of acetaldehyde for raising 
the conversion ratio of 2-pyrrolidone over 97 mol %. 
In the case of conducting the precipitation of 
N-(.alpha.-hydroxyethyl)pyrrolidone in a reaction vessel different from 
the original reaction vessel, a small excess amount of acetaldehyde to 
2-pyrrolidone is added, and the reaction mixture is transferred to the 
reaction vessel wherein the precipitation of 
N-(.alpha.-hydroxyethyl)pyrrolidone is effected, when the conversion ratio 
of 2-pyrrolidone becomes 50 to 90 mol %, preferably 60 to 90 mol %. Or 
else, after adding acetaldehyde in an amount less than equimolar to 
2-pyrrolidone to the reaction mixture, the reaction mixture is transferred 
to the reaction vessel wherein the precipitation of 
N-(.alpha.-hydroxyethyl)pyrrolidone is effected, and after further adding 
acetaldehyde in an amount so that the total amount of the thus added 
acetaldehyde is a little excess to 2-pyrrolidone, 
N-(.alpha.-hydroxyethyl)pyrrolidone is precipitated. 
In addition, in the case of precipitating the crystals of 
N-(.alpha.-hydroxyethyl)pyrrolidone, it is preferable to use a dispersing 
medium which does not dissolve the crystals of 
N-(.alpha.-hydroxyethyl)pyrrolidone but disperse thereof in the system. 
Such a dispersing medium may be coexistent with the reactants at the 
starting time of the reaction, or may be added just before the 
precipitation of the crystals. However, in the case of carrying out the 
reaction at a temperature of lower than 25.degree. C. and precipitating 
the crystals, it is preferable to make a dispersing medium which dissolves 
2-pyrrolidone and disperses the crystals of 
N-(.alpha.-hydroxyethyl)pyrrolidone without dissolving thereof, coexistent 
with the reactants at the starting time of the reaction. As the dispersing 
medium, aliphatic hydrocarbons such as cyclohexane, hexane, heptane, etc. 
which hardly dissolve both 2-pyrrolidone and 
N-(.alpha.-hydroxyethyl)pyrrolidone, and aromatic hydrocarbons such as 
benzene, toluene, xylene, etc. which dissolves 2-pyrrolidone but hardly 
dissolves N-(.alpha.-hydroxyethyl)pyrrolidone, ethers such as diethyl 
ether, tetrahydrofuran, etc. and esters such as ethyl acetate, etc. may be 
exemplified. 
The amount of the dispersing medium for use in the first step of the 
present process is suitably selected from the range of 0.2 to 3 times by 
weight of the amount of 2-pyrrolidone. 
Alternatively, the yield of N-(.alpha.-hydroxyethyl)pyrrolidone can be 
raised by further supplying acetaldehyde into the reaction mixture instead 
of cooling and adding the crystal nuclei to the reaction system. 
According to the present invention, the thus obtained 
N-(.alpha.-hydroxyethyl)pyrrolidone is reacted with a primary alcohol, a 
secondary alcohol or a derivative thereof in the presence of an acidic 
catalyst in the second step of the present process. 
In the present application, the derivative of alcohol includes alkylene 
glycol and ether thereof, polyalkylene glycol and ether thereof, and 
glycerol. 
As the alcohol or the derivative thereof used according to the present 
invention, although a suitable member may be optionally selected from 
primary alcohols, a derivative thereof, secondary alcohols and a 
derivative thereof, C.sub.1-10 primary alcohol, a derivative thereof, 
C.sub.1-10 secondary alcohol and a derivative thereof is preferable, and 
C.sub.1-10 aliphatic alcohol is more preferable from the viewpoints of the 
reactivity of the alcohol or the derivative thereof and the solubility of 
N-(.alpha.-hydroxyethyl)pyrrolidone to the alcohol and the derivative 
thereof. Although polyvalent alcohol is not preferable, because it gives 
more than two kinds of reaction products, it does not hinder producing 
N-vinylpyrrolidone by cleaving the alkoxy group. As the example of 
preferable primary alcohols, methanol, ethanol, n-propanol, n-butanol, 
n-pentanol, n-hexanol, n-heptanol, n-octanol, and benzyl alcohol, as the 
example of secondary alcohols, isopropyl alcohol, isobutanol, and as a 
derivative of alcohols, 2-methoxyethanol, 2-ethoxyethanol, 
2-propoxyethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, 
ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol and 
glycerol may be exemplified. 
The amount of the alcohol or the derivative thereof to 
N-(.alpha.-hydroxyethyl)pyrrolidone may be optionally decided, however, 
because of the thermal instability of N-(.alpha.-hydroxyethyl)pyrrolidone 
and of the difficulty in recovering N-(.alpha.-hydroxyethyl)pyrrolidone 
after finishing the reaction, it is preferable to use the alcohol or the 
derivative thereof in an equimolar or larger amount, namely ordinarily 1.0 
to 30 times by mol of the amount of N-(.alpha.-hydroxyethyl)pyrrolidone. 
Since N-(.alpha.-hydroxyethyl)pyrrolidone is a crystalline compound, it is 
preferable to use the alcohol or the derivative thereof as a solvent, and 
in such a case, the amount of the used alcohol or derivative thereof is 
preferably 2 to 30 times by mol of the amount of 
N-(.alpha.-hydroxyethyl)pyrrolidone. 
In order to limit the amount of the alcohol or the derivative thereof used 
in the reaction as small as possible, a solvent which is inert in the 
reaction may be suitably used. Even in the case where a part of 
N-(.alpha.-hydroxyethyl)pyrrolidone presents as crystals in the reaction 
system, it is liquefied after reaction with the alcohol or the derivative 
thereof and accordingly, the inert solvent used herein may be the 
substance dissolving N-(.alpha.-hydroxyethyl)pyrrolidone or the substance 
used only for dispersing N-(.alpha.-hydroxyethyl)pyrrolidone in the 
reaction system. In the case of using such a solvent, the amount of the 
used alcohol or derivative thereof is preferably one to six times by mol 
of the amount of N-(.alpha.-hydroxyethyl)pyrrolidone. 
As the catalyst used in the reaction between 
N-(.alpha.-hydroxyethyl)pyrrolidone and the alcohol or the derivative 
thereof, any one of the ordinary acidic catalysts may be used in general, 
and for instance, inorganic acids, organic acids, weakly acidic- or 
strongly acidic ion-exchanging resins, solid acids, etc. may be 
exemplified, and strongly acidic substances such as sulfuric acid, 
hydrochloric acid, nitric acid, hydrobromic acid, sulfamic acid, 
methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, 
cross-linked polystyrenesulfonic acid, etc. are preferable. The acidic 
catalyst is used in an amount of 0.001 to 10 mol % to the amount of 
N-(.alpha.-hydroxyethyl)pyrrolidone ordinarily, and preferably 0.005 to 8 
mol %, and more preferably 0.1 to 5 mol %. 
In the case where the amount of the catalyst is below 0.001 mol %, the 
reaction rate is extremely slow, and on the other hand, in the case of 
over 10 mol %, the yield of the product is low due to the occurrence of 
side reactions. 
In addition, in the case of using a heterogeneous catalyst such as 
ionexchanging resin, the reaction may be carried out by passing the 
mixture of the reactants through a column in which the catalyst has been 
filled. 
Although the temperature of reaction between 
N-(.alpha.-hydroxyethyl)pyrrolidone and the alcohol or the derivative 
thereof may be selected from the range of -10.degree. to 100.degree. C., 
it is preferable to carry out the reaction at a temperature in the range 
of from 0.degree. to 80.degree. C. The reaction rate is extremely slow at 
the temperature of below -10.degree. C., and on the other hand, 
decomposition of N-(.alpha.-hydroxyethyl)pyrrolidone occurs at a 
temperature of over 100.degree. C., thereby reducing the yield of the 
pyrrolidone derivative of the formula (I). 
In the case where the reaction is carried out in line with the process 
according to the present invention, it is easy to obtain the pyrrolidone 
derivative of the formula (I) in a yield of 90 to 98%, and it is more 
preferable to carry out the reaction while removing water formed in the 
reaction between N-(.alpha.-hydroxyethyl)pyrrolidone and the alcohol on 
the derivative thereof out of the reaction system, because the yield of 
the objective product is further improved. 
Although the removal of water can be effected ordinarily at an optional 
temperature in the range of -10.degree. to 80.degree. C., it is preferably 
carried out at a temperature in the range of 10.degree. to 50.degree. C. 
The removal of water may be carried out by using any method of the known 
methods, however, it is preferably carried out by adding a dehydrating 
agent or by distilling water off from the reaction system. Although an 
optional dehydrating agent may be ordinarily used, a dehydrating agent of 
from neutral to acidic nature or preferably a dehydrating agent of from 
neutral to weakly acidic nature is used. As an example of the preferable 
dehydrating agent, molecular sieves, calcium chloride, sodium sulfate, 
magnesium sulfate and calcium sulfate may be exemplified. 
The dehydrating agent may be coexistent with the reactants at the starting 
time of the reaction, and it may be added during the reaction. 
Water may be distilled off under an ordinary pressure or a reduced 
pressure, however, it is preferred to distill water off under a reduced 
pressure. In the case of carrying out the distillation of water under an 
ordinary pressure, the reaction temperature frequently elevates over 
80.degree. C. even by the use of an azeotropic solvent which boils with 
water and accordingly it is necessary to carefully carry out distillation 
of water under ordinary pressure. 
In the case where the alcohol or the derivative thereof which is reacted 
with N-(.alpha.-hydroxyethyl)pyrrolidone is azeotropic with water, water 
is brought into azeotropic distillation with the alcohol or the derivative 
thereof, and after separating the alcohol or the derivative thereof from 
water, the thus separated alcohol or the derivative thereof is added to 
the reaction mixture or the same amount of new alcohol or derivative 
thereof as the amount of the respective alcohol or derivative thereof 
distilled off from the reaction system by azeotropic distillation is added 
to the reaction mixture. The removal of water by distillation can be also 
carried out in the presence of a solvent. 
As the solvent, a solvent which is distilled azeotropically with water and 
is easily separated from water is preferably used, and for example, 
hexane, cyclohexane, heptane and the like may be exemplified. 
The amount of the solvent used in the removal of water is selected from the 
range of 0.01 to 5 times by weight of the amount of 
N-(.alpha.-hydroxyethyl)pyrrolidone used in the reaction. 
Such a solvent may be added preliminarily at the starting time of the 
reaction of N-(.alpha.-hydroxyethyl)pyrrolidone with the alcohol or the 
derivative thereof, and may be added just before the distillation of 
water. 
According to the present invention, it is possible to produce the 
pyrrolidone derivative of the formula (I) in a far higher yield of 90 to 
98% than that in the conventional process and with an industrial 
profitability. 
The present invention will be explained more in detail while referring to 
the following non-limitative examples.

EXAMPLE 1 
Synthesis of N-(.alpha.-n-butoxyethyl)pyrrolidone 
Into a mixture of 127.7 g (1.5 mol) of 2-pyrrolidone and 0.075 g (0.036 mol 
% of 2-pyrrolidone) of potassium carbonate, 78.9 g (1.79 mol) of gaseous 
acetaldehyde were supplied within 3.5 hours, while warming by a water bath 
at a temperature of 28.degree. C. and stirring vigorously. The reaction 
mixture was cooled to 5.degree. C. under stirring, and by adding 5 mg of 
N-(.alpha.-hydroxyethyl)pyrrolidone as the crystallization nuclei to the 
reaction mixture, the thus formed N-(.alpha.-hydroxyethyl)pyrrolidone was 
crystallized. On analyzing the thus formed product by liquid 
chromatography, the conversion ratio of 2-pyrrolidone was 99.0 mol %, and 
the selectivity in forming N-(.alpha.-hydroxyethyl)pyrrolidone based on 
2-pyrrolidone was 100 mol %. 
To the thus obtained reaction mixture, a mixed liquid of 1.5 g of sulfuric 
acid and 400 g of n-butanol was added, thereby dissolving 
N-(.alpha.-hydroxyethyl)pyrrolidone and reacting the dissolved 
N-(.alpha.-hydroxyethyl)pyrrolidone. 
After finishing the dissolution of N-(.alpha.-hydroxyethyl)pyrrolidone, the 
temperature of the reaction system was still raised, and the reaction was 
continued for 30 min while maintaining the temperature at 20.degree. C. On 
analyzing the reaction product by liquid chromatography, the conversion 
ratio of 2-pyrrolidone was 95 mol % and the selectivity to 
N-(.alpha.-hydroxyethyl)pyrrolidone was 5.6 mol %. After neutralizing the 
reaction mixture by potassium hydroxide, the unreacted 
N-(.alpha.-hydroxyethyl)pyrrolidone was decomposed into 2-pyrrolidone. On 
analyzing the reaction product by gas-chromatography, the conversion ratio 
to 2-pyrrolidone was 89.8 mol %, and the selectivity of 
N-(.alpha.-n-butoxyethyl)pyrrolidone based on 2-pyrrolidone was 99.9 mol 
%. 
EXAMPLE 2 
Synthesis of N-(.alpha.-n-butoxyethyl)pyrrolidone 
In the same manner as in Example 1 except for using the starting materials 
in the respective amounts as shown below, 
N-(.alpha.-n-butoxyethyl)pyrrolidone was synthesized. 
______________________________________ 
Starting material 
Amount (g) 
______________________________________ 
2-pyrrolidone 85.1 
acetaldehyde 44.9 
potassium carbonate 
0.1 
n-butanol 296 and 
sulfuric acid 0.5. 
______________________________________ 
The conversion ratio of 2-pyrrolidone was 96.7 mol %, and the selectivity 
of N-(.alpha.-hydroxyethyl)pyrrolidone was 3.4 mol %. 
After neutralizing the reaction mixture by potassium hydroxide, the 
reaction mixture was subjected to analysis by gas-chromatography. As the 
result thereof, the conversion ratio of 2-pyrrolidone was found to be 93.3 
mol % and the selectivity of N-(.alpha.-n-butoxyethyl)pyrrolidone based on 
2-pyrrolidone was found to be 99.8 mol %. 
EXAMPLE 3 
Synthesis of N-(.alpha.-n-butoxyethyl)pyrrolidone 
To 85.1 g (1 mol) of 2-pyrrolidone, 0.16 g (0.12 mol % to 2-pyrrolidone) of 
potassium carbonate and 155.8 g (1.8 times by weight of the amount of 
2-pyrrolidone) of cyclohexane were added, and the thus formed mixture was 
vigorously stirred while warming the mixture by a water bath at 28.degree. 
C. and supplying 44.9 g (1.02 mol) of gaseous acetaldehyde thereinto 
within 3.5 hours. Then, the reaction mixture was cooled to 8.degree. C. 
under stirring, and 5 mg of N-(.alpha.-hydroxyethyl)pyrrolidone were added 
thereto as crystallization nuclei, thereby crystallizing the reaction 
system. 
On analyzing the reaction mixture by liquid chromatography, the conversion 
ratio of 2-pyrrolidone was 99.6 mol % and the selectivity of 
N-(.alpha.-hydroxyethyl)pyrrolidone based on 2-pyrrolidone was 100 mol %. 
By adding a mixed solution of 0.6 g of sulfuric acid and 296 g of 
n-butanol, the thus crystallized N-(.alpha.-hydroxyethyl)pyrrolidone was 
reacted while dissolving the crystals thereof. 
On analyzing the thus obtained reaction mixture by liquid chromatography, 
the conversion ratio of 2-pyrrolidone was 99.6 mol % and the selectivity 
of N-(.alpha.-hydroxyethyl)pyrrolidone based on 2-pyrrolidone was 4.0 mol 
%. 
After neutralizing the reaction mixture by potassium hydroxide, the thus 
neutralized reaction mixture was analyzed by gas-chromatography, and as a 
result the conversion of 2-pyrrolidone was 95.6 mol % and the selectivity 
of N-(.alpha.-n-butoxyethyl)pyrrolidone was 99.6 mol %. 
EXAMPLES 4 to 8 
In a similar manner to that in Example 3, 
N-(.alpha.-n-butoxyethyl)pyrrolidone was produced by using the respective 
amounts of 2-pyrrolidone, acetaldehyde, potassium carbonate, n-butanol and 
sulfuric acid at the respective reaction temperature in the presence of 
the respective amounts of the respective kinds of solvents shown in Table 
1. 
After having neutralized the reaction mixture by potassium hydroxide, the 
thus neutralized reaction mixture was analyzed by gaschromatography, the 
results thereof being shown also in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Selectivity 
(mol %) of N--(a- 
Reaction Coversion 
n-butoxyethyl)- 
Ex- 
Amount (g) of 
Ratio of K.sub.2 CO.sub.3 
Solvent temper- (mol %) 
pyrrolidone 
am- 
2-pyrro- 
acetal- 
to 2-pyrrolidone 
Amount 
ature 
Amount (g) of 
of 2- based on 2- 
ple 
lidone 
dehyde 
(mol %) Kind (g) (.degree.C.) 
n-butanol 
H.sub.2 SO.sub.4 
pyrrolidone 
pyrrolidone 
__________________________________________________________________________ 
4 85.1 52.5 
0.036 Toluene 
85.3 25 296.0 
0.6 92.4 100 
5 85.1 47.5 
0.11 Hexane 65.9 28 296.0 
0.7 95.6 99.8 
6 85.1 51.5 
0.36 Cyclohexane 
77.9 28 296.0 
0.9 93.7 100 
7 170.2 
92.9 
0.11 Cyclohexane 
311.6 
28 593.0 
1.3 95.6 100 
8 170.2 
92.3 
0.15 Cyclohexane 
311.6 
28 596.0 
1.3 95.9 99.7 
__________________________________________________________________________ 
EXAMPLE 9 
To 170.2 g (2 mols) of 2-pyrrolidone, 0.41 g (0.15 mol % to 2-pyrrolidone) 
of potassium carbonate and 331.6 g of cyclohexane were added, and the 
mixture was vigorously stirred while warming the mixture in a water bath 
at 28.degree. C. and supplying 94.6 g (2.14 mols) of gaseous acetaldehyde 
thereinto within 4 hours. The reaction mixture was then cooled to 
8.degree. C. under stirring and by adding 5 mg of 
N-(.alpha.-hydroxyethyl)pyrrolidone, as crystallization nuclei, the 
reaction mixture was subjected to crystallization. 
To the thus crystallized reaction mixture, a liquid mixture of 1.3 g of 
sulfuric acid and 593 g of n-butanol was added, thereby dissolving the 
crystallized N-(.alpha.-hydroxyethyl)pyrrolidone and reacting the thus 
dissolved N-(.alpha.-hydroxyethyl)pyrrolidone. After dissolving 
N-(.alpha.-hydroxyethyl)pyrrolidone, 111.1 g of dried molecular sieve 5A 
was added to the thus treated reaction mixture, and the reaction was 
warmed to 20.degree. C. and stirred for 2 hours at the temperature. 
Thereafter, the reaction mixture was left to stand still for 10 hours. 
On analyzing the thus treated reaction mixture by liquidchromatography, the 
conversion ratio of 2-pyrrolidone was 99.7 mol % and the selectivity of 
N-(.alpha.-hydroxyethyl)pyrrolidone based on 2-pyrrolidone was 2.7 mol %. 
After neutralizing the reaction mixture by potassium hydroxide, the thus 
neutralized reaction mixture was subjected to analysis by 
gas-chromatography and as a result the conversion ratio of 2-pyrrolidone 
was 97.0 mol % and the selectivity of N-(.alpha.-n-butoxyethyl)pyrrolidone 
was 100 mol %. 
EXAMPLE 10 
To 85.1 g (1 mol) of 2-pyrrolidone, 0.15 g (0.11 mol % to 2-pyrrolidone) of 
potassium carbonate and 155.8 (1.83 times by weight of the amount of 
2-pyrrolidone) of cyclohexane were added, and while warming the mixture in 
a water bath at 28.degree. C. under vigorous agitation, 45.2 g (1.03 mols) 
of acetaldehyde were supplied into the mixture within 4 hours. The 
reaction mixture was cooled to 8.degree. C. under stirring and 5 mg of 
N-(.alpha.-hydroxyethyl)pyrrolidone as crystallization nuclei were added 
to the reaction mixture, thereby crystallizing the reaction mixture. 
To the thus crystallized reaction mixture, a liquid mixture of 0.6 g of 
sulfuric acid and 296 g of n-butanol was addled, thereby dissolving the 
crystallized N-(.alpha.-hydroxyethyl)pyrrolidone and bringing thereof into 
reaction. Thereafter, cyclohexane and water of the reaction mixture were 
distilled off by azeotropic distillation from the reaction mixture at 
30.degree. C. under a reduced pressure of 100 mmHg. After having carried 
out the azeotropic dehydration for 2 hours, the pressure on the dehydrated 
residue was restored to atmospheric pressure, and the temperature of the 
residue was maintained at 20.degree. C. 
On analyzing the residue (the dehydrated reaction mixture) by 
liquid-chromatography, the conversion ratio of 2-pyrrolidone was 99.1 mol 
% and the selectivity of N-(.alpha.-hydroxyethyl)pyrrolidone based on 
2-pyrrolidone was 2.4 mol %. 
After having neutralized the reaction mixture by potassium hydroxide, the 
neutralized reaction mixture was subjected to gaschromatographic analysis 
and as a result the conversion ratio of 2-pyrrolidone was 97.6 mol % and 
the selectivity of N-(.alpha.-n-butoxyethyl)pyrrolidone based on 
2-pyrrolidone was 99.8 mol %. 
EXAMPLE 11 
Synthesis of N-(.alpha.-hydroxyethyl)pyrrolidone 
Into a mixture of 85.1 g of 2-pyrrolidone and 0.5 g of sodium carbonate 
(0.47 mol % per unit molar amount of 2-pyrrolidone), 48.5 g of gaseous 
acetaldehyde was supplied within 3.5 hours, while being warmed by a water 
bath of a temperature of 30.degree. C. 
After the reaction was over, the reaction mixture was analyzed by liquid 
chromatography and the reaction ratio of 2-pyrrolidone was 71.5 mol % and 
the selectivity in forming N-(.alpha.-hydroxyethyl)pyrrolidone based on 
2-pyrrolidone was 80.5 mol %. 
EXAMPLE 12 
Synthesis of N-(.alpha.-iso-propoxyethyl)pyrrolidone 
To 80 g of N-(.alpha.-hydroxyethyl)pyrrolidone (0.62 mol), 160.5 g of 
isopropyl alcohol (2.67 mol) was added and the mixture was stirred at 
20.degree. C. to make a solution. 6.1 g of isopropanol solution of 5 wt % 
sulfuric acid was added to the solution and brought to a reaction for 30 
minutes. 
After the reaction was over, the reaction mixture was analyzed by a liquid 
chromatography and the reaction ratio of 
N-(.alpha.-hydroxyethyl)pyrrolidone was 91.4 mol % and the selectivity in 
forming N-(.alpha.-iso-propoxyethyl)pyrrolidone based on 
N-(.alpha.-hydroxyethyl)pyrrolidone was 98.3 mol %. 
EXAMPLE 13 
Synthesis of N-(.alpha.-methoxyethyl)pyrrolidone 
To 70 g of N-(.alpha.-hydroxyethyl)pyrrolidone (0.54 mol), 70 g of methanol 
(2.2 mol) was added and the mixture was stirred at 20.degree. C. to make a 
solution. 2 g of dried Diaion PK 208H (cross-linked polystyrenesulfonic 
acid resin, made by Mitsubishi Chemical Industries Co.) was added to the 
solution and after 30 minutes of reaction, the reaction mixture was 
analyzed with a liquid chromatography. The reaction ratio of 
N-(.alpha.-hydroxyethyl)pyrrolidone was 98.6 mol % and the selectivity in 
forming N-(.alpha.-methoxyethyl)pyrrolidone based on 
N-(.alpha.-hydroxyethyl)pyrrolidone was 99.6 mol %. 
EXAMPLE 14 
A 200 ml four-necked flask was fitted with a stirrer having a 
fluorine-resin blade, a gas in-let tube a thermometer and an 
ice-water-jacketed condenser equipped with a vent, then, a trap containing 
a small amount of paraffin was connected to the open end of the vent. 
To a 100 ml pressure glass vessel equipped with a needle valve, were added 
55 g of acetaldehyde, then, the vessel was connected to the gas in-let 
tube of the flask through a fluorine-resin tube with the needle valve 
closed. 
To the flask, were added 63.8 g of 2-pyrrolidone and 0.4 g of trisodium 
phosphate decahydrate (0.14 mol % based on the mole of 2-pyrrolidone), and 
the content was vigorously stirred on a water bath of 30.degree. C. 
Separately, the vessel containing acetaldehyde was allowed to warm on a 
water bath of 40.degree. C., and gaseous acetaldehyde was introduced into 
the reaction system in the flask through the gas in-let tube by opening 
the needle valve, thereby initiating the reaction. 
During the course of the reaction, the needle valve was so controlled that 
the maximum supplying rate of gaseous acetaldehyde was obtained while 
taking a caution not to allow gaseous acetaldehyde to escape through the 
paraffin in the trap. 
The time taken to supply 45.2 g of acetaldehyde into the reaction system 
was 2.5 hours. 
After the reaction was over, the reaction mixture was analyzed by liquid 
chromatography, and the reaction ratio of 2-pyrrolidone was 97.2 mol % and 
the selectivity in forming N-(.alpha.-hydroxyethyl)pyrrolidone based on 
2-pyrrolidone was 99.5 mol %. 
EXAMPLE 15 
A 200 ml four-necked flask was fitted with a stirrer having a 
fluorine-resin blade, a gas in-let tube a thermometer and an 
ice-water-jacketed condenser equipped with a vent, then, a trap containing 
a small amount of paraffin was connected to the open end of the vent. 
To a 100 ml pressure glass vessel equipped with a needle valve, were added 
55 g of acetaldehyde, then, the vessel was connected to the gas in-let 
tube of the flask through a fluorine-resin tube with the needle valve 
closed. 
To the flask, were added 63.8 g of 2-pyrrolidone and 0.4 g of sodium 
orthosilicate (0.29 mol % based on the mole of 2-pyrrolidone), and the 
content was vigorously stirred on a water bath of 30.degree. C. 
Separately, the vessel containing acetaldehyde was allowed to warm on a 
water bath of 40.degree. C., and gaseous acetaldehyde was introduced into 
the reaction system in the flask through the gas in-let tube by opening 
the needle valve, thereby initiating the reaction. 
During the course of the reaction, the needle valve was so controlled that 
the maximum supplying rate of gaseous acetaldehyde was obtained while 
taking a caution not to allow gaseous acetaldehyde to escape through the 
paraffin in the trap. 
The time taken to supply 40.7 g of acetaldehyde into the reaction system 
was one hour. 
After the reaction was over, the reaction mixture was analyzed by liquid 
chromatography, and the reaction ratio of 2-pyrrolidone was 89.6 mol % and 
the selectivity in forming N-(.alpha.-hydroxyethyl)pyrrolidone based on 
2-pyrrolidone was 97.1 mol %. 
The reaction mixture was cooled to 0.degree. C. with stirring and 5 mg of 
N-(.alpha.-hydroxyethyl)pyrrolidone was added thereinto as crystallization 
nuclei. After 10 min., the reaction mixture turned white and solidified. 
The reaction mixture was analyzed by liquid chromatography, and the 
reaction ratio of 2-pyrrolidone was 96.5 mol % and the selectivity in 
forming N-(.alpha.-hydroxyethyl)pyrrolidone based on 2-pyrrolidone was 
96.3 mol %. 
COMATIVE EXAMPLE 1 
Synthesis of N-(.alpha.-hydroxyethyl)pyrrolidone using potassium hydroxide 
as a catalyst 
To a 200 ml four-necked flask equipped with a stirrer having a 
fluorine-resin blade, a thermometer and a reflux condenser, were added 
42.6 g of 2-pyrrolidone and 22.1 g of acetaldehyde, then, the mixture was 
stirred violently. 
To the mixture, was added 0.176 g of potassium hydroxide (85% content) and 
the mixture was heated at 70.degree. C. under reflux for 30 min. 
After the reaction was over, the reaction mixture was analyzed by liquid 
chromatography, and the reaction ratio of 2-pyrrolidone was 28.5 mol % and 
the selectivity in forming N-(.alpha.-hydroxyethyl)pyrrolidone based on 
2-pyrrolidone was 43.2 mol %. 
COMATIVE EXAMPLE 2 
Synthesis of N-(.alpha.-hydroxyethyl)pyrrolidone using sodium hydroxide as 
a catalyst 
A mixture of 85.1 g of 2-pyrrolidone and 44.1 g of acetaldehyde was stirred 
vigorously and 0.3 g of sodium hydroxide (0.75 mol % to 2-pyrrolidone) was 
added to the mixture. The mixture was brought into reaction for 30 minutes 
at 70.degree. C. under reflux. 
After the reaction was over, the reaction mixture was analyzed by a liquid 
chromatography and the reaction ratio of 2-pyrrolidone was 27.5 mol % and 
the selectivity in forming N-(.alpha.-hydroxyethyl)pyrrolidone based on 
2-pyrrolidone was 42.8 mol %. 
COMATIVE EXAMPLE 3 
Synthesis of N-(.alpha.-hydroxyethyl)pyrrolidone using polyphosphoric acid 
as a catalyst 
A mixture of 85.1 g of 2-pyrrolidone and 1.3 g of polyphosphoric acid was 
stirred vigorously while being warmed by a water bath of a temperature of 
30.degree. C. 44.1 g of gaseous acetaldehyde was charged into the mixture 
within 3.5 hours. 
Immediately after the supply of acetaldehyde was over, the reaction mixture 
was analyzed by a liquid chromatography. The reaction ratio of 
2-pyrrolidone was 87.1 mol % and the selectivity in forming 
N-(.alpha.-hydroxyethyl)pyrrolidone based on 2-pyrrolidone was 43.7 mol %.