Preparation of azo compounds having carboxyl and cyano groups

A process for the preparation of a diazocyano acid, which comprises reacting a keto-acid or its sodium salt with a cyanogen compound such as sodium cyanide or hydrogen cyanide and a hydrazine in water to form a concentrated aqueous solution of a hydrazo compound, adding acetone or acetone and water to the concentrated aqueous solution to form an acetone-water solution of the hydrazo compound, adding an oxidant such as chlorine gas to the solution to oxidize the hydrazo compound and form a diazocyano acid, forming at least two transparent liquid layers by adding acetone and/or water to the obtained reaction mixture during or after oxidation if necessary, and further adding sodium chloride to the reaction mixture if necessary, and separating and recovering the upper layer of the acetone-water solution containing the diazocyano acid from the mixture.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The invention relates to a process for preparing a diazocyano acid such as 
4,4'-azobis-(4-cyanovaleric acid) using a keto-acid such as levulinic acid 
or a sodium salt of keto-acid as the starting material. 
2. Background Information 
Diazocyano acids have been used as an initiator for polymerization such as 
homopolymerization of acrylamide or 1,3-butadiene or copolymerization of 
1,3-butadiene with acrylonitrile (see, e.g., Japanese Examined patent 
publication (Kokoku) No. 43-28474 and Japanese Unexamined patent 
publication (Kokai) Nos. 56-133305 and 57-198720). 
As means for the preparation of diazocyano acids, there is known a process 
comprising reacting a keto-acid or its sodium salt with a cyanogen 
compound such as sodium cyanide or hydrogen cyanide and a hydrazine such 
as hydrazine hydrate or hydrazine sulfate in water to form a hydrazo 
compound, adding chlorine gas to the obtained solution to oxidize the 
hydrazo compound and form a diazocyano acid and filtering off the solid 
diazocyano acid from the obtained reaction mixture (see, also, Japanese 
Examined patent publication (Kokoku) No. 43-28474 and Japanese Unexamined 
patent publication (Kokai) No. 56-133305). 
However, this known process has the following problems: 
(a) Since sodium chloride is formed as a by-product in an amount of at 
least 2 moles per mole of a diazocyano acid when the diazocyano acid is 
synthesized, a large amount of sodium chloride is contained in the 
diazocyano acid product. A diazocyano acid containing a large amount of 
sodium chloride is not preferred as the initiator for homopolymerization 
of 1,3-butadiene or copolymerization of 1,3-butadiene with acrylonitrile. 
(b) If a refining step is arranged for removing sodium chloride contained 
in the diazocyano acid, the yield of the diazocyano acid is drastically 
reduced. 
SUMMARY OF THE INVENTION 
The inventors conducted extensive research with a view to developing a 
novel process for the preparation of diazocyano acids in which the 
above-mentioned problems are overcome, and as the result, we have 
completed the present invention. 
More specifically, in accordance with the present invention, there is 
provided a process for the preparation of a diazocyano acid, which 
comprises reacting a keto-acid or its sodium salt with a cyanogen compound 
such as sodium cyanide or hydrogen cyanide and a hydrazine in water to 
form a concentrated aqueous solution of a hydrazo compound, adding acetone 
or acetone and water to the concentrated aqueous solution to form an 
acetone-water solution of the hydrazo compound, adding an oxidant such as 
chlorine gas to the solution to oxidize the hydrazo compound and form a 
diazocyano acid, forming at least two transparent liquid layers by adding 
acetone and/or water to the obtained reaction mixture during or after 
oxidation if necessary, and further adding sodium chloride to the reaction 
mixture if necessary, and separating and recovering the uppermost layer of 
the acetone-water solution containing the diazocyano acid and if 
necessary, separating the diazocyano acid from the solution. 
According to the present invention, diazocyano acids can be prepared in a 
high yield. 
Furthermore, according to the present invention, the mixture of acetone and 
water is formed into two liquid layers containing the diazocyano acid and 
sodium chloride, respectively, by adjusting the ratio of acetone to water 
in the resulting reaction mixture within a specific range, preferably from 
80/20 to 33/67, especially from 80/20 to 60/35, and thus, the upper layer 
of the acetone-water solution containing the diazocyano acid can be 
separated very easily. Therefore, the process of the present invention is 
industrially advantageous. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the process of the present invention, it is preferred that a keto-acid 
or its sodium salt (per 1 mole) be reacted with a cyanogen compound (0.95 
to 1.5 mole, more preferably 1 mole) and a hydrazine (0.45 to 0.6 mole, 
more preferably 0.5 mole) in the presence or absence of a mineral acid 
such as hydrochloric acid or an alkali such as sodium hydroxide in a small 
amount of water, and a concentrated aqueous solution of a hydrazo compound 
may be obtained according to any of the following processes. 
The aqueous solution of the hydrazo compound may be in a slurry state or in 
a transparent liquid state. 
(a) When the hydrazo compound is formed by reacting a keto-acid or its 
sodium salt with a mixture of the cyanogen compound such as sodium cyanide 
or hydrogen cyanide and the hydrazine. This reaction is carried out, 
preferably at a temperature of not higher than 50.degree. C., especially 
15.degree. to 40.degree. C., in the presence of water in an amount of 10 
to 200 parts, especially 15 to 100 parts by weight per 100 parts by weight 
of the keto-acid or its sodium salt. 
(b) When the hydrazo compound is formed by contacting a keto-acid or its 
sodium salt with the cyanogen compound such as sodium cyanide or hydrogen 
cyanide and contacting the reaction product with the hydrazine to form 
cyanohydrin, the reaction is carried out, preferably at a temperature of 
not higher than 50.degree. C., especially not higher than 20.degree. C., 
in the presence of water in an amount of 80 to 200 parts by weight per 100 
parts by weight of the keto-acid or its sodium salt. 
(c) A keto-acid or its sodium salt is reacted with the hydrazine in water 
in an amount of 50 to 500 parts, especially 50 to 200 parts by weight per 
100 parts by weight of the keto-acid or its sodium salt to form a 
ketazine, and the ketazine is reacted with the cyanogen compound such as 
hydrogen cyanide or sodium cyanide to form a concentrated aqueous solution 
of the hydrazo compound. Preferably, the reaction temperature is not 
higher than 100.degree. C., especially 5.degree. to 35.degree. C. 
It is preferred that, in the formation of the hydrazo compound by each 
process (a) to (c) as mentioned above, the pH value of the reaction system 
is adjusted to 5 to 9, especially 5.5 to 7.3 after the addition of the 
respective reactants. The pH value may be adjusted in a usual manner, for 
example, by addition of an aqueous NaOH or HCl. 
Where a concentrated aqueous solution of the hydrazo compound is not 
employed, the yield of the diazocyzano acid may be low. 
Among the processes (a) to (c), the process (c) is particularly preferred. 
As a preferred example of the keto-acid, there can be mentioned levulinic 
acid. 
As a preferred example of the diazocyano acid, there can be mentioned 
4,4'-azobis-(4-cyanovaleric acid). 
As examples of the hydrazine, there can be mentioned hydrazine hydrate. 
According to the process of the present invention, there may be obtained, 
for example, a concentrated aqueous solution of the reaction product, that 
is, a hydrazo compound of the following formula, at the above-mentioned 
step: 
##STR1## 
wherein R stands for alkyl of 1 to 6 carbon atoms, M stands for Na or H, 
and n is an integer of 1 to 6. 
In the present invention, acetone or an acetone-water mixed solvent is 
added to the above-mentioned concentrated aqueous solution to form an 
acetone-water solution of the hydrazo compound in which the acetone/water 
volume ratio is preferably from 80/20 to 33/67, more preferably from 80/20 
to 65/35. 
Where an unreacted cyanogen compound (NaCN, HCN) or hydrazine may be 
retained in the above-mentioned concentrated aqueous solution of the 
hydrazo compounds, it is preferred that chlorine gas is added to the 
solution, after the addition of water as required, to react it with the 
unreacted compound, and thereafter, acetone or acetone and water are added 
to form an acetone-water solution containing the hydrazo compound and then 
chlorine gas is added to oxidize the hydrazo compound. 
In the process of the present invention, an oxidant such as chlorine gas is 
added to the above solution preferably in an amount of at least 0.5 mole, 
more preferably 0.5 to 1 mole, especially 0.5 to 0.75 mole, per mole of 
the keto-acid or its sodium salt to oxidize the hydrazo compound and form 
the diazocyano acid. It is preferred that this oxidation reaction be 
carried out at a temperature lower than 30.degree. C., especially lower 
than 15.degree. C. 
Addition of the oxidant can be performed according to known procedures at 
the above-mentioned oxidizing step. 
In the process for the present invention, the acetone/water volume ratio in 
the so-obtained reaction mixture containing the diazocyano acid is 
preferably adjusted to from 80/20 to 33/67, especially from 80/20 to 
65/35, if necessary by adding acetone and or water to the reaction 
mixture, and sodium chloride is further added if necessary, whereby the 
reaction mixture is formed into two liquid layers, at least the upper 
layer of which is transparent. The upper layer of the acetone-water 
solution containing the diazocyano acid is separated and recovered 
preferably at a temperature of 0.degree. to 50.degree. C., especially 
15.degree. to 50.degree. C. 
In the process of the present invention, when the diazocyano acid is formed 
by the above-mentioned oxidation reaction, sodium chloride is formed as a 
by-product in an amount of at least 2 moles per mole of the diazocyano 
acid. In the process of the present invention, by adjusting the ratio of 
acetone to water in the reaction mixture, sodium chloride formed as the 
by-product is dissolved or partially precipitated in the lower layer 
(containing a small amount of acetone) and only a very small amount of 
sodium chloride is dissolved in the upper layer of the acetone-water 
solution having the diazocyano acid dissolved therein. Furthermore, if 
sodium chloride is added afresh to the mixture having the two separated 
layers, the proportion of the lower layer is increased and the amount of 
water in the diazocyano acid-containing acetone-water solution of the 
upper layer is decreased. Accordingly, the amount of sodium chloride 
contained in the acetone-water solution of the diazocyano acid becomes 
smaller than before the addition of sodium chloride. It is preferred that 
to sodium chloride to be added afresh until the volumes of the two layers 
do not change any more or a small amount of NaCl is retained undissolved 
in the lower layer. 
If the ratio of acetone to water in the mixtue is outside the 
above-mentioned range when the diazocyano acid-containing acetone-water 
solution is separated and recovered, the mixture may not be separated into 
two layers or the separation may be difficult. If the ratio of acetone to 
water is within the above-mentioned range, especially, from 75/25 to 
50/50, sodium chloride need not be added afresh or the amount of sodium 
chloride to be added afresh can be reduced, and the operation of 
recovering the upper layer from the two liquid layers is facilitated and 
can be accomplished by an ordinary separating method. 
In the process of the present invention, in the case where hydrochloric 
acid is contained in the reaction mixture, it is preferred that a alkaline 
compound such as sodium hydroxide, sodium carbonate or sodium 
hydrogen-carbonate be added to neutralize hydrochloric acid and adjust the 
pH value of the solution to 3 to 5, especially 3 to 4.5. 
In the process of the present invention, the diazocyano acid may be 
recovered by evaporating and removing acetone and water from the 
diazocyano acid-containing acetone-water solution and adding a small 
amount of water to the residual solid to effect water washing, or 
preferably, there may be adopted a method in which acetone is evaporated, 
water is added to the residue and the diazocyano acid is recovered by 
filtration. It is preferred that water be added to the residue left after 
evaporation of acetone in an amount of 100 to 1000 parts by weight, 
especially 100 to 500 parts by weight, per 100 parts by weight of the 
diazocyano acid, and the solid diazocyano acid be separated and recovered 
at a temperature lower than 30.degree. C., especially lower than 
10.degree. C., particularly after mixing the liquid homogeneously. If 
necessary, the recovered diazocyano acid may be dried under reduced 
pressure to remove a small amount of water contained in the diazocyano 
acid crystal. 
According to the process as mentioned above, a diazocyano acid having an Na 
content lower than 3000 ppm, especially lower than 600 ppm can be prepared 
in a high yield, and if water washing is repeated several times, the Na 
content can be greatly reduced. 
The diazocyano acid obtained by the above-mentioned process of the present 
invention may be purified to further reduce the Na content by dissolving 
the resulting diazocyano acid in a mixed solution of acetone and water at 
a volume ratio of from 75/25 to 95/5, preferably 75/25 to 90/10, 
evaporating acetone from the solution and washing the residue with water. 
By this purification procedure, the Na content of the diazocyano acid can 
be reduced to a level of lower than 5 ppm. It is preferred that the 
diazocyano acid having an Na content lower than 8000 ppm, especially lower 
than 3000 ppm, be dissolved in the above-mentioned acetone-water solution. 
It is preferred that the amount of the diazocyano acid is 1 to 60 g, 
especially 5 to 30 g, per 100 ml of the acetone-water solution. It is also 
preferred that the diazocyano acid be dissolved in the acetone-water 
solution at a temperature lower than 50.degree. C., especially lower than 
40.degree. C. Acetone is removed by evaporation from the acetone-water 
solution containing the diazocyano acid (it is not necessary to completely 
remove acetone at this step), and the diazocyano acid precipitated in the 
remaining aqueous solution is separated, recovered and washed with water. 
There is preferably adopted a process in which water is added to the 
precipitated diazocyano acid in the aqueous solution to effect water 
washing and the diazocyano acid is recovered by filtration. 
In the above-mentioned process, it is preferred that evaporation of acetone 
from the acetone-water solution containing the diazocyano acid be carried 
out at a temperature lower than 50.degree. C., especially lower than 
40.degree. C. It also is preferred that acetone be evaporated until the 
acetone/water volume ratio is from 25/75 to 0/100, especially from 10/90 
to 0/100 before filtration. 
In the process, preferably, water is added to the residue left after the 
above-mentioned step of evaporation of acetone in an amount of 100 to 1500 
parts by weight, especially 100 to 1000 parts by weight, per 100 parts by 
weight of the diazocyano acid, preferably followed by mixing, and the 
solid diazocyano acid is separated and recovered at a temperature lower 
than 10.degree. C., preferably lower than 3.degree. C. Separation and 
recovery of the diazocyano acid can be accomplished by known means. 
It is preferred that the diazocyano acid separated and recovered at the 
above-mentioned step be washed with water in an amount of 50 to 400 parts 
by weight, especially 100 to 250 parts by weight, per 100 parts by weight 
of the diazocyano acid at a temperature lower than 10.degree. C., 
especially lower than 3.degree. C. If necessary, a small amount of water 
contained in the diazocyano acid may be removed by drying reduced 
pressure. 
According to the above-mentioned process, a diazocyano acid having an Na 
content lower than 5 ppm can be obtained at a recovery ratio higher than 
90%, and if the above-mentioned procedures are repeated on the so-obtained 
diazocyano acid having the reduced Na content, further purified diazocyano 
acid can be obtained. 
The diazocyano acid prepared according to the process of the present 
invention can be used as the initiator for homopolymerization of 
1,3-butadiene or copolymerization of 1,3-butadiene with acrylonitrile. 
Further, the diazocyano acid-containing acetone-water solution formed as 
the upper layer according to the process of the present invention can be 
used as the initiator solution without isolating the diazocyano acid. 
It is preferred that the polymerization temperature be 70.degree. to 
130.degree. C. and the polymerization time be 1 to 40 hours. It is 
preferred that the amount of the diazocyano acid be 5 to 20 parts by 
weight per 100 parts by weight of the monomer component (1,3-butadiene or 
the sum of 1,3-butadiene and acrylonitrile). The method for the addition 
of the diazocyano acid or the acetone-water solution containing the 
diazocyano acid is not particularly critical. The solution may be added 
intermittently or continuously. It is preferred that a carboxyl-terminated 
liquid polymer having an acrylonitrile content of up to 45% by weight, 
especially 15 to 35% by weight, a number average molecular weight of 1000 
to 5000 and a functional group number of 1.8 to 2.5 per mole be formed by 
appropriately adjusting the polymerization conditions. 
The so-separated liquid polymer may be mixed with an antioxidant according 
to a known method. 
Unreacted 1,3-butadiene is removed from the polymerization reaction mixture 
if necessary, and water is added to the polymerization reaction mixture to 
wash the liquid polymer and the liquid polymer is separated and recovered. 
It is preferred that the liquid polymer be dried in an evaporator until 
the weight is not changed any more. Thus, the intended carboxyl-terminated 
polymer is obtained. 
It is preferred that the amount of water added at this step be 100 to 400 
parts by weight per 100 parts by weight of the carboxyl-terminated liquid 
polymer. 
In the case where unreacted 1,3-butadiene is not removed from the 
polymerization reaction mixture, it is preferred that water be added so 
that the amount of acetone is 50 to 300 parts by weight, the amount of 
1,3-butadiene is 10 to 100 parts by weight and the amount of water is 100 
to 400 parts by weight per 100 parts by weight of the carboxyl-terminated 
liquid polymer. After the addition of water, mixing is preferably carried 
out to disperse the polymer, and when the mixture is allowed to stand 
still, preferably for 2 minutes to 10 hours, the mixture is separated into 
the phase of the liquid polymer-acetone solution and the phase of the 
acetone-water solution. The liquid polymer is separated and recovered from 
this mixture. If necessary, a small amount of water contained in the 
liquid polymer-acetone solution may be removed by centrifugal separation. 
In the process of the present invention, by separating the liquid polymer 
from the acetone-water solution, water-soluble compounds formed as 
by-products at the step of preparing the diazocyano acid are removed in 
the state dissolved in the acetone-water solution. Furthermore, 
substantially all of a small amount of sodium chloride contained in the 
acetone-water solution of the diazocyano acid used as the polymerization 
initiator is removed from the liquid polymer. 
The so-separated liquid polymer is dried in an evaporator until the weight 
is not changed any more. 
As the evaporator, there may be used centrifugal film evaporators such as a 
lateral centrifugal film evaporator, a vertical centrifugal film 
evaporator and a VL-type centrifugal film evaporator. 
The carboxyl-terminated liquid polymer prepared according to the process of 
the present invention can be used for the production of electro-deposition 
paints and powder paints and IC packaging materials.

The present invention will now be described in detail with reference to the 
following examples and comparative examples. In the examples, the pH of 
the reaction mixture was adjusted to 4 after the addition of all the three 
reaction components. 
EXAMPLE 1 
A 1-liter 4-neck flask equipped with a stirrer, a gas-introducing pipe, a 
gas vent and a dropping pipe was charged with 25.25 g (0.53 mole) of NaCN, 
15 ml of H.sub.2 O and 12.52 g (0.25 mole) of NH.sub.2 NH.sub.2. H.sub.2 
O, and the mixture was stirred at 25.degree. C. A part of NaCN was left 
granular even after stirring. Then, a liquid formed by adding 8 g of 
concentrated HCl to 58 g (0.5 mole) of levulinic acid was dropped to the 
mixture while maintaining the reaction temperature at 25.degree. to 
28.degree. C. A faintly yellow, slightly viscous slurry was formed and the 
insoluble granules of NaCN disappeared during the dropwise addition. After 
completion of the dropwise addition, the temperature was elevated to 
35.degree. C. and reaction was carried out for 2 hours at this 
temperature. The mixture was kept in the slurry state. The mixture was 
cooled to 5.degree. C., and 540 ml of acetone and 36 ml of H.sub.2 O 
cooled to 5.degree. C. were added to the mixture. Then, 21.3 g (0.3 mole) 
of Cl.sub.2 gas was blown into the mixture with violent stirring while 
cooling the mixture so that the reaction temperature did not exceed 
10.degree. C. After the reaction, the temperature was returned to 
20.degree. C. and 200 ml of water was added, and the mixture was stirred 
and allowed to stand still to separate the mixture into two liquid layers. 
The acetone/water volume ratio in the mixture at this point was 67.7/32.3. 
The formed liquid was transferred into a separating funnel and 10 g of 
NaCl was added, and the mixture was shaken and allowed to stand still. The 
lower layer having NaCl granules precipitated therein was removed, and the 
faintly yellow transparent upper layer was maintained at 20.degree. C. 
and acetone was removed by distillation using an aspirator to precipitate 
a large amount of 4,4'-azobis-(4-cyanovaleric acid) (hereinafter referred 
to as ACVA). The temperature was lowered to 5.degree. C. and ACVA was 
recovered by suction filtration. The recovered ACVA was dried under 
reduced pressure at 20.degree. C. until the weight was not changed, 
whereby 63.50 g of pure-white ACVA was obtained. The yield was 90.6% based 
on levulinic acid. One peak was observed by the liquid chromatography. The 
results of the elementary analysis of ACVA (C.sub.12 H.sub.16 N.sub.4 
O.sub.4) were as follows: 
Calculated Values: C=51.43%, H=5.75%, N=19.99%. 
Found Values: C=51.29%, H=5.58%, N=20.04%. 
The Na content in ACVA was 430 ppm as determined by the atomic absorption 
spectroscopy. 
EXAMPLE 2 
A concentrated aqueous solution of a hydrazo compound was prepared in the 
same manner as described in Example 1, and this aqueous solution in the 
form of a slurry was cooled to 5.degree. C. and 540 ml of acetone and 240 
ml of H.sub.2 O cooled to 5.degree. C. were added. Then, 21.3 g (0.3 mole) 
of Cl.sub.2 gas was blown into the mixture while cooling the mixture so 
that the reaction temperature did not exceed 10.degree. C. If stirring was 
stopped after the reaction, the mixture was separated into two liquid 
layers. The formed liquid was transferred into a separating funnel, and 10 
g of NaCl was added to the mixture and the mixture was shaken and allowed 
to stand still. The lower layer having NaCl granules precipitated therein 
was removed and the faintly yellow transparent upper layer was recovered. 
The post treatment and drying were carried out in the same manner as 
described in Example 1 to obtain 62.81 g of pure-white ACVA. The yield was 
89.6% based on levulinic acid. One peak was observed by the liquid 
chromatography. The results of the elementary analysis of ACVA (C.sub.12 
H.sub.16 N.sub.4 O.sub.4) were as follows: 
Calculated Values: C=51.43%, H=5.75%, N=19.99%. 
Found Values: C=51.44%, H=5.76%, N=19.97%. 
The Na content in ACVA was 493 ppm as determined by the atomic absorption 
spectroscopy. 
EXAMPLE 3 
A 1-liter 4-neck flask equipped with a stirrer, a gas-introducing pipe, a 
gas vent and a dropping pipe was charged with 58.0 g (0.5 mole) of 
levulinic acid, 3.5 g of concentrated HCl and 5 ml of H.sub.2 O. While the 
reaction temperature was maintained at 5.degree. C., an aqueous solution 
of 25.25 g (0.53 mole) of NaCN in 50 ml of H.sub.2 O was dropped to the 
mixture. Solidification was promptly caused at the final stage of the 
dropwise addition. Then, 7 g of concentrated HCl and 12.52 g (0.25 mole) 
of NH.sub.2 NH.sub.2.H.sub.2 O were added to the reaction mixture and the 
temperature was elevated to 35.degree. C. When the temperature exceeded 
the level of 20.degree. C., stirring became possible, and at 33.degree. C. 
the slurry was converted to a faintly yellow transparent liquid. Reaction 
was carried out at 35.degree. C. for 3 hours, and the reaction mixture was 
cooled to 5.degree. C. and 540 ml of acetone was added thereto. Then, 21.3 
g (0.3 mole) of Cl.sub.2 gas was blown into the liquid while maintaining 
the liquid temperature below 10.degree. C. After the reaction, the 
temperature was returned to 20.degree. C., and 200 ml of H.sub.2 O was 
added to the reaction mixture and the mixture was stirred and allowed to 
stand still, whereby the mixture was separated into two liquid layers. The 
subsequent operations were conducted in the same manner as described in 
Example 1 to obtain 56.9 g of pure-white ACVA. One peak was observed by 
the liquid chromatography. The results of the elementary analysis of ACVA 
(C.sub.12 H.sub.16 N.sub.4 O.sub.4) were as follows: 
Calculated Values: C=51.34%, H=5.75%, N=19.99%. 
Found Values: C=51.40%, H=5.74%, N=19.98%. 
The Na content in ACVA was 510 ppm as determined by the atomic absorption 
spectroscopy. 
EXAMPLE 4 
A 2-liter 4-neck flask equipped with a stirrer, a gas-introducing pipe and 
a dropping pipe was charged with 58.0 g (0.5 mole) of levulinic acid and 
50 ml of H.sub.2 O, and the charge was cooled to 5.degree. C. Then, 12.52 
g (0.25 mole) of hydrazine hydrate was dropped to the charge so that the 
liquid temperature did not exceed 10.degree. C. At this point, the mixture 
was a colorless viscous slurry. For about 15 minutes from the point of 
completion of the dropwise addition, stirring was conducted below 
10.degree. C., and an aqueous solution of 25.25 g (0.53 mole) of NaCN in 
50 ml of H.sub.2 O was added to the mixture so that the liquid temperature 
did not exceed 10.degree. C. Midway in the addition of the aqueous 
solution, the mixture was converted to a faintly yellow transparent liquid 
from the slurry. Then, 2.5 g of concentrated HCl was added to the mixture 
to adjust the pH value to 7.0. The temperature was elevated to 20.degree. 
C. and the liquid was stirred for 15 hours at this temperature. Then, the 
reaction mixture was cooled to 5.degree. C. and 700 ml of acetone was 
added to the mixture, and 21.3 g (0.3 mole) of Cl.sub.2 gas was blown into 
the mixture so that the temperature did not exceed 10.degree. C. After the 
reaction, the temperature was returned to 20.degree. C., and 230 ml of 
water was added to the reaction mixture so that the acetone/water volume 
ratio was 67/33. When the reaction mixture was stirred and allowed to 
stand still, the mixture was separated into two liquid layers. The 
subsequent operations were conducted in the same manner as described in 
Example 1 to obtain 58.9 g of pure-white ACVA. The yield was 84% based on 
levulinic acid. The results of the elementary analysis were in agreement 
with the calculated values of ACVA (C.sub.12 H.sub.16 N.sub.4 O.sub.4). 
The Na content in ACVA was 498 ppm. 
EXAMPLE 5 
A flat bottom flask having a capacity of 1 liter was charged with 50 g of 
dried ACVA (having an Na content of 498 ppm and obtained as in Example 4), 
and 300 ml of an acetone-water mixed solvent (A/W=75/25) was added and 
ACVA was dissolved therein at a temperature lower than 40.degree. C. Then, 
acetone was removed by distillation under reduced pressure at a 
temperature lower than 40.degree. C., whereby ACVA was gradually 
precipitated in water. After acetone had been completely removed, 300 ml 
of distilled water was added to the solution having ACVA precipitated 
therein. The mixture was stirred under cooling to 1.degree. to 3.degree. 
C. for 30 minutes and suction filtration was carried out by using G4 glass 
filter, and the recovered solid was washed with 100 ml of distilled water 
(1.degree. to 3.degree. C.) two times and dried under reduced pressure in 
the presence of P.sub.2 O.sub.5 to recover 47.1 g (94%) of ACVA having an 
Na content of 1.3 ppm as determined by the atomic absorption spectroscopy. 
Then, a flat bottom flask having a capacity of 500 ml was charged with 30.0 
g of the sample obtained above, and 250 ml of an acetone-water mixed 
solvent (A/W=75/25) was added and the sample was dissolved therein at a 
temperature lower than 40.degree. C. When acetone was removed by 
distillation under reduced pressure, ACVA was gradually precipitated in 
water. After acetone had been completely removed, 100 ml of distilled 
water was added to the solution having ACVA precipitated therein and the 
mixture was stirred under cooling to 1.degree. to 3.degree. C. for 30 
minutes. Suction filtration was performed by G4 glass filter and the solid 
was washed with 100 ml of distilled water (1.degree. to 3.degree. C.) two 
times and dried under reduced pressure in the presence of P.sub.2 O.sub.5 
to recover 27.6 g (92%) of ACVA having an Na content of 0.3 ppm as 
determined by the atomic absorption spectroscopy. 
COMATIVE EXAMPLE 1 
A reaction vessel equipped with a stirrer, a gas-introducing pipe, a gas 
vent and a dropping pipe was charged with 0.963 kg (8.3 mole) of levulinic 
acid and 1.0 l of water, and the mixture was cooled to 5.degree. C. After 
addition of 0.058 kg of concentrated hydrochloric acid and 0.3 l of water, 
a solution of 0.420 kg (8.5 mole) of NaCN in 1.6 l of water was added 
dropwise to the mixture while cooling the mixture so that the reaction 
temperature did not exceed 10.degree. C., and thereafter, the mixture was 
left to react at a temperature not higher than 10.degree. C. for 15 
minutes. No product was precipitated, unlike in Example 1. To the mixture 
0.208 kg (4.15 mole) of NH.sub.2 NH.sub.2.H.sub.2 O was added dropwise, 
and the mixture was left to react at 35.degree. C. for 3 hours. The 
mixture was then cooled to 5.degree. C., added with 3.3 l of acetone and 
then with 0.31 kg (4.4 mole) of Cl.sub.2 gas, and left to react while 
keeping the temperature below 10.degree. C. Acetone was removed by 
distillation under reduced pressure from the reaction mixture in which 
ACVA was partially precipitated to precipitate a large amount of ACVA. 
Crude ACVA was obtained by suction filtration over the period of 3 hours. 
The crude ACVA was washed with 0.7 l of water, filtered, and dried under 
reduced pressure to obtain 0.69 kg of ACVA. The NaCl content in ACVA was 
2000 ppm. 
EXAMPLE 6 
A 20-liter 4-neck flask equipped with a stirrer, a gas-introducing pipe, a 
gas vent and a dropping pipe was charged with 284.8 g (5.811 mole) of 
NaCN, 165 ml of H.sub.2 O and 137.3 g (2.741 mole) of NH.sub.2 NH.sub.2 
H.sub.2 O, and the mixture was stirred at 25.degree. C. A major of NaCN 
was left granular even after stirring. Then, a liquid formed by adding 
54.8 g of concentratred HCl to 636.6 g (5.483 mole) of levulinic acid was 
added dropwise to the mixture while maintaining the reaction temperature 
at 20 to 22.degree. C. A faintly yellow, slightly viscous slurry was 
formed and the insoluble granules of NaCN disappeared during the dropwise 
addition. To the mixture 54.8 g of concentrated HCl was added, the 
temperature was elevated to 35.degree. C. and reaction was carried out for 
1 hour at this temperature. The mixture was then cooled to 5.degree. C. 
with ice water and left to stand for 2 hours. The mixture was kept in a 
white slurry state. The mixture was cooled to 3.degree. C., 494 ml of 
water was added while again starting stirring, and 6372 ml of acetone of 
4.degree. C. was added to the mixture. Then, 233 g (3.29 mole) of Cl.sub.2 
gas was blown into the mixture while cooling the mixture so that the 
reaction temperature did not exceed 10.degree. C. The mixture was added 
with 2.3 l of distilled water, stirred at 20.degree. C., and the stirring 
was stopped. Thus, the mixture was clearly separated into two layers. The 
upper acetone solution layer was recovered by a separating funnel in an 
amount of 7.2 l. The acetone solution contained 697 g of ACVA. The Na 
content was 500 ppm. 
This liquid was used as an initiator solution for poly-merization. A 35 l 
autoclave equipped with a magnetic stirrer, a thermometer, a 
charge-injection pipe, a coiled condenser and a vent was charged with 5275 
g of 1,3-butadiene, 1136 g of acrylonitrile and 755 g of acetone, and the 
mixture was heated to 85.degree. C. At this temperature, 630 ml of the 
initiator solution which contained 60 g of ACVA was injected into the 
autoclave. Additional portions of ACVA and acrylonitrile were added every 
30 minutes according to the following addition program. 
______________________________________ 
Hrs. from Hrs. from 
starting 
Acrylo- starting Acrylo- 
polymeri- 
nitrile ACVA polymeri- 
nitrile 
ACVA 
zation (g) (g) zation (g) (g) 
______________________________________ 
0.5 34.5 38.5 9.5 19.2 14.5 
1.0 33.9 35.8 10.0 18.6 13.9 
1.5 32.4 33.7 10.5 17.7 13.3 
2.0 31.2 31.6 11.6 17.4 12.9 
2.5 30.3 29.8 11.5 16.8 12.9 
3.0 29.1 28.0 12.0 16.2 12.6 
3.5 28.2 26.2 12.5 15.6 12.3 
4.0 27.3 24.7 13.0 15.3 12.0 
4.5 26.4 23.5 13.5 14.7 11.7 
5.0 25.5 22.0 14.0 14.1 11.4 
5.5 24.6 21.1 14.5 13.8 11.1 
6.0 24.0 19.9 15.0 13.2 10.8 
6.5 23.1 19.0 15.5 12.9 10.5 
7.0 22.2 18.1 16.0 12.6 10.5 
7.5 21.6 17.2 16.5 12.0 10.2 
8.0 21.0 16.3 17.0 11.7 9.9 
8.5 20.4 15.7 17.5 11.1 9.9 
9.0 19.5 15.1 
______________________________________ 
The polymerization time was 18 hours, and the polymerization temperature 
was maintained at 85.degree. C. .+-.0.2.degree. C. except for the 
temperature drops within 2.degree. C. for about 2 minutes at the time of 
the addition of the acrylonitrile and ACVA. 
After the polymerization for 18 hours, ice water was introduced into the 
coiled condenser and the autoclave was dipped into ice water to rapidly 
cool the reaction mixture and stop the polymerization. 20,000 g of water 
was added to 14200 g of the polymerization liquid, and the mixture was 
stirred and then left to stand. Thus, the mixture was rapidly separated 
into two layers. The lower water-acetone layer was removed, and the upper 
polymer layer was added with 5000 g of acetone to dissolve the polymer. 
Then 8500 g of water was added, and the mixture was stirred and then left 
to stand for 3 hours. After the separation of the mixture into two layers, 
the lower layer was removed and the upper polymer layer was dried in a 
centrifugal film evaporator until the weight was not changed any more, 
whereby 6260 g of a carboxyl-terminated liquid polymer was obtained. The 
monomer conversion was 81.5%. 
This liquid copolymer had an acrylonitrile content of 24.9 mole %, an acid 
value of 1830 g/eq, and an Na content of 31.0 ppm as measured by 
atomic-absorption spectroscopy. The ratio of the molecular-weight 
distribution indices Mw/Mn was 1.96. 
EXAMPLE 7 
The upper acetone solution layer as in Example 6 was obtained in an amount 
of 108 l. Acetone was distilled off from the acetone solution under 
reduced pressure, 3 l of water was added to form a slurry, and the slurry 
was stirred at 5.degree. C. for 1 hour, filtered, and washed with 7 l of 
water of 5.degree. C. Thus, 1572 g of wet ACVA was obtained. The wet ACVA 
was dissolved in a mixture of 8.5 l of acetone and 0.55 l of water. The 
resultant acetone-water solution of ACVA contained 945 g of ACVA and had 
an Na content of 56 ppm. 
Using the acetone-water solution of ACVA, the polymerization procedure as 
in Example 6 was repeated, and the resultant polymer was washed with water 
and dried. 
Thus, 6350 g of a carboxyl-terminated butadieneacrylonitrile copolymer was 
obtained. This copolymer had an acrylonitrile content of 25.1%, an acid 
value of 1910 g/eq, and an Na content of 2.3 ppm as measured by 
atomic-absorption spectroscopy.