CH653984A5 - PREPARATION OF ALKENE CARBONATES. - Google Patents

Description

The invention relates to a process for the preparation of alkene carbonates by reacting the corresponding alkene oxides with carbon dioxide. These reactions are well known to those skilled in the art. The alkenes carbonates are useful solvents and can be used in the manufacture of the corresponding glycols.

Several processes have been described which make it possible to obtain a glycol by hydration of the corresponding alkene oxide in a single step, in the presence of a catalyst and carbon dioxide. Such methods would reduce the amount of water required. The removal of excess water represents a significant cost in the conventional hydration process. Carbon dioxide is not consumed in the process; it has been suggested that an alkene carbonate is formed as an intermediate in the mechanism of the hydration reaction.

US Patent No. 3,922,314 describes a process for the manufacture of ethylene glycol by hydration of ethylene oxide, which does not use a catalyst: the reaction is carried out with an aqueous solution of ethylene oxide containing at at least 8% ethylene oxide (by weight) and at least 0.1% carbon dioxide (by weight).

A catalytic process is described in English patent No. 1177877 (or US patent No. 3629343). The alkenes oxides are transformed into glycols by hydration at a temperature of 80 ° -220 ° C and at a pressure of 10-180 atmospheres in the presence of a halide as catalyst. The preferred catalysts are halides of alkali metals or quaternary amines, in particular bromides and iodides. The presence of hydroxides, carbonates and bicarbonates of alkali metals has been described as being beneficial.

A similar process is described in US Patent No. 4,160,116, where quaternary phosphine halides - preferably iodides and bromides - are used to catalyze the hydration of alkenes oxides in the presence of carbon dioxide. The temperature is 50-200 ° C, and the pressure 3-50 kg / cm2.

Another process is further described in Japanese published patent application No. 81-45426, in which derivatives of molybdenum and / or tungsten are combined with known catalysts, such as the alkali metal halides, the amine or phosphine salts. qua-5 ternaries, organic halides and amines. The reaction is described as being carried out at 20-250 ° C and at 0-30 kg / cm2.

The preparation of alkenes carbonates - unlike the hydration of alkenes oxides to glycols - is carried out according to the prior art in the absence of water. Catalysts and reaction conditions similar to those described above for the hydration of alkene oxides have been recognized as useful.

In US Patent No. 2,667,497, calcium or magnesium halides were used at 150-250 ° C and 500-2000 psi to produce alkenes carbonates from the corresponding oxides.

US Patent No. 2,766,258 describes the use of hydroxides, carbonates and bicarbonates of quaternary amines to catalyze the reaction of alkene oxides with carbon dioxide; the reaction was carried out at temperatures of 100-225 ° C and pressures of 300-20 5000 psi (pounds per square inch).

The quaternary amine halides have been used by the authors of US Patent No. 2,773,070 at temperatures of 100-225 ° C and pressures above 300 psi.

The authors of US Pat. No. 2,773,881 have used amines as catalysts. The reaction was carried out at 100-400 ° C and at a pressure of 500 psi, and above.

US Patents Nos. 2994705, 2994704 and 2993908, granted to the same agent, give essentially the same operating conditions, ie 93-260 C and 8-212 kg / cm2, with quaternary phosphine halides, sulfin halides, and urea hydrohalides to catalyze the formation of alkene carbonates from the corresponding epoxides.

The hydrazine or halides of hydrazine were used to catalyze this reaction by the authors of US Pat. No. 3535341 at a temperature of 100-250 ° C. An anion exchange resin containing quaternary ammonium groups was described in US Patent No. 4,232,221 as a catalyst for this gas phase reaction.

Japanese published patent application No. 80-122776 describes the use of halides of organic antimony derivatives as catalysts for the reaction of alken carbonate formation at a temperature between room temperature and 120 ° C. in a waterless environment.

The authors of the present invention have found that the transformation of oxides of alkenes into corresponding carbonates can be carried out with known catalysts at temperatures lower than those practiced until now and in the presence of large amounts of water. The hydrolysis of carbonates to glycol is minimized and the main reaction product is carbonate. In addition, the higher temperatures previously used to produce glycols can be employed to produce carbonates instead, without significant amounts of glycols being formed, particularly higher glycols. This requires maintaining the carbon dioxide / alkene oxide molar ratio at a value 55 greater than about 1/1 and the partial pressure of carbon dioxide above a determined value.

The alkene oxides react with carbon dioxide to form alkene carbonates in the presence of sufficient quantities of suitable catalyst at temperatures above 20 ° C, more particularly above 90 ° C and preferably between 90 ° and 170 ° C, and in the presence of water, when the carbon dioxide / alkene oxide molar ratio is equal to or greater than 1/1, and the partial pressure of carbon dioxide is sufficiently high. Under these conditions, alkene carbonate is obtained selectively. The pressure at which the reaction takes place is approximately 10-200 kg / cm2, and preferably 30 to 80 kg / cm2. The catalysts for this reaction include one or more compounds from the group consisting of amine halides, quaternary phosphines, sulfide halides

3

653,984

born, organic halides of antimony, in particular methyl triphenyl phosphine iodide, tetraethyl amine bromide, tetraphenyl antimony bromide. The corresponding carboxylates can also be used. The amount of catalyst used is generally up to 0.10 mole per mole of alkene oxide, and it is preferable to use an amount ranging from 0.001 to 0.02.

Contrary to what one might expect, water can be present in a large quantity, even in excess of that used in the hydration processes of the prior art: in fact, the formation of appreciable quantities of glycols, and in particular higher glycols, is avoided by maintaining the molar ratio of carbon dioxide / alkene oxide to a value greater than 1/1, and by suitably adjusting the partial pressure of carbon dioxide. Under these conditions, alkene carbonate is obtained selectively. The water / alkene oxide ratio should be adjusted to a value greater than about 0.01 / 1, preferably 0.1 / 1 to 4/1, the optimum being between 0.1 / 1 and 2 / 1. However, larger quantities of water cannot be excluded. The addition of water also increases the rate of carbonate formation.

Until now, those familiar with the process for preparing alkenes carbonates from alkenes and carbon dioxide oxides have carried out this reaction at temperatures generally situated in the range 100-300 ° C., and more particularly 150-225 ° C. Although this aspect has not been discussed in detail, the descriptions made previously allow to conclude that the reaction was carried out practically in the absence of water. For example in US Patent No. 4233221, the reagents were dried by compression and condensation of water, so that their humidity was quite low, about 0.2% (by moles). As it was known that carbonates are hydrolyzed at high temperature in the presence of the catalysts used to obtain glycol directly from alkene oxides by hydrolysis, it is likely that efforts have been made to avoid water when wanted to produce carbonates. In the presence of water, one could expect hydrolysis phenomena leading to the appearance of glycol.

The authors of the present invention have discovered that alkene carbonates can be obtained from alkene oxides and carbon dioxide in the presence of water. The alkene carbonates thus obtained contain only minimal amounts of glycol resulting from hydrolysis, and in particular of higher glycols. Such a process can be carried out continuously on a stream containing carbon dioxide, ethylene oxide and water resulting from the extraction of ethylene oxide from a dilute aqueous solution using carbon dioxide. The reaction can be carried out at temperatures lower than those which have been considered possible up to now (ie above 20 ° C), and at elevated temperatures (ie above 90 ° C) without producing significant amounts of glycols, in particular higher glycols, provided that the carbon dioxide / alkene oxide molar ratio is maintained at a value greater than about 1/1, and that the partial pressure of carbon dioxide is maintained at a sufficiently high value. Under these conditions, alkene carbonate is obtained selectively.

The reaction can be carried out over a wide range of temperatures above 20 ° C., in particular above 90 ° C., and preferably between 90 and 170 ° C. It is preferable to use high temperatures, because the rate of carbonate formation is higher.

The total pressure at which the reaction is to be carried out is not particularly critical. Usually, we will work at a pressure of 10-200 kg / cm2. However, it has been found that the value of the partial pressure of carbon dioxide is a very important factor.

The carbon dioxide / alkene oxide molar ratio should be greater than about 1/1, and may be in the range 1/1 to 100/1. Usually, we will choose a ratio greater than 1/1 located in the range 1/1 to 10/1. When the process of the present invention is used in combination with an extraction of alkene oxide with carbon dioxide, the ratio can go up to 40 / 1-60 / 1.

It is very important that water does not hydrolyze alkene carbonates into glycols, particularly higher glycols, under the conditions defined in the present invention. The authors of the present invention have found that the formation of glycols can be limited, if a sufficient amount of carbon dioxide is present. This result was not foreseeable, because the prior art indicated to us that water - in particular at high temperature - hydrolyzes the oxides of alkenes into glycols. One might think that when carbon dioxide was present, an alkene carbonate was formed as an intermediate (see for example US Pat. Nos. 4237324 and 4117250, as well as US Pat. No. 3,629,343 granted to Levin et al.). The alkene carbonate apparently does not form in significant quantities, since the authors indicated that the glycol yields were quantitative.

The amount of water which can be tolerated in the reaction depends on the operating conditions and influences the selectivity of the reaction. At low temperatures, it is possible to have greater amounts of water than those used in the direct hydrolysis of alkene oxides to glycols, as we will see later in the examples. At temperatures above about 90 ° C, and in particular between 90 and 170 ° C, water / alkene oxide molar ratios of up to about 4/1 are preferred, and preferably between 0.1 / 1 and 2/1. The presence of water has a beneficial effect on the rate of carbonate formation, which is contrary to expectation. This effect can be increased by the presence of certain catalysts, in particular those where the halogen atom is linked to the rest of the molecule rather by an ionic than covalent bond, such as for example the preferred catalysts which are the halides of quaternary phosphines.

The catalysts which have proven effective in the process of the present invention include many of those which are already known in the art. Catalysts which may prove to be effective comprise one or more compounds from the classes consisting of amines and quaternary phosphine halides, sulfin halides, and halides of organic antimony compounds. The corresponding carboxylates can also be used. Examples of quaternary amines which can be used include tetraethyl amine bromide and tetraethyl amine iodide. Examples of quaternary phosphines include methyl triphé-40 nyl phosphine iodide and methyl triphenyl phosphine bromide. Sulfines include trimethyl solfonium iodide, and trimethyl sulfonium bromide. Antimony derivatives are effective in the absence of water, but their activity seems to be reduced when it is present. Typical antimony derivatives are tetraphenyl antimony bromide, and triphenyl antimony dichloride. The preferred catalysts in the presence of water are methyl triphenyl phosphine iodide and tetraethyl amine bromide. Among the halides, it is preferred to use bromides and iodides.

The amount of catalyst is similar to that used in the other 50 processes, up to about 0.1 mole of catalyst per mole of alkene oxide; the preferred concentration range is 0.001 to 0.02 moles per mole, although larger or smaller amounts may also be used.

While other authors working in the same field have indicated that high temperatures (100 ° C or higher) are necessary to produce alkenes carbonates in the absence of water, or to produce glycols by hydrolysis of the oxides d alkenes, the process of the present invention makes it possible to use temperatures situated above 20 ° C., in particular above 90 ° C., and preferably between 90 and 170 ° C.

The reaction by which the carbonates are obtained can be carried out in the presence of large quantities of water. At the high temperatures normally used in the past, glycol formation could be expected when water was present; it is on this 65 idea that several manufacturing processes are based, as we have seen above. As we will see, it is possible to minimize hydrolysis and to obtain carbonates in place of glycols - even at high temperatures - in contro-

653,984

4

the carbon dioxide / alkene oxide molar ratio and the partial pressure of carbon dioxide.

The first five examples illustrate the formation of alkenes carbonates at temperatures below 90 ° C.

Example 1

Reactions at temperatures below 900 C and without water

A sample of catalyst to be tested is introduced into a 130 cm3 reactor manufactured by Parr Instrument Company. Ethylene oxide and CO 2 are introduced into the reactor cooled to -78; C by immersion in a dry ice / acetone bath. The reactor is then closed and placed in a bath at 36: C. The interior 5 of the reactor is thus heated to 30: C, and the reaction is carried out. Agitation is ensured by a magnetic stirrer. After an appropriate period of time, the reactor is removed from the bath and its contents are analyzed. The results of a number of tests are given in Table A below.

Table A

Test No

Supply millimoles OE * C02

Catalyst g ***

Bath ° C

Time h

Max pressure kg / cm2

OE *% conv.

CE **% select.

1

13.6

681

a 0.1456

36

19.5

28.1

51.7

-

2

13.6

681

b 0.4385

36

19.5

29.5

55

16

3

18.2

681

c 0.3657

32

19.5

18.3

94

88.2

4

15.9

681

d 0.3064

37

18.5

15.5

37.7

-

5

18.2

1022

e 0.3881

38

19.5

30.6

51.1

-

6

22.7

1022

f 0.2406

38

19.5

78.1

77.9

50.4

* OE = ethylene oxide ** CE = ethylene carbonate *** a = trimethyl sulfonium iodide b = methyl triphenyl phosphine iodide

c = tetraphenyl antimony bromide d = triphenyl antimony dichloride e = methyl triphenyl phosphine bromide f = tetraethyl amine bromide

It has been found that water can be present in the reaction medium without significant quantities of glycols appearing, provided that the temperature is sufficiently low. It has been surprisingly found that water has a beneficial effect on the selectivity of the carbonate formation reaction with certain catalysts, while with other catalysts this selectivity appears to decrease.

30 Example 2

Effect of water on the catalyst

These tests were carried out under the same conditions as in Example 1, except that different quantities of water were introduced into the Parr reactor.

Table B

Test No

oe

Co2 millimoles supply

h2o

Catalyst g *

Bath ° C

Time h

Max pressure kg / cm2

oe% conv.

CE% sel.

7

19.3

1022

-

c 0.5507

33

19.5

27.8

91.1

88.5

8

18.2

1022

10

c 0.5466

34

19.5

27.4

95.6

47.1

9

20.4

1022

5

b 0.4380

37

21

44.3

86

35

10

20.4

1022

20

b 0.4227

37

21

42.5

92

47.4

11

20.4

1022

40

b 0.4319

37

21

43.2

93

63

12

22.7

1022

80

b 0.4365

37

21

41.1

83.8

76

* c = tetraphenyl antimony bromide b = methyl triphenyl phosphine iodide

The results in Table B show that water does not appear to have a significant effect on the conversion of ethylene oxide. The formation of ethylene carbonate is however reduced in the presence of catalyst “c” and surprisingly increased in the presence of catalyst “b”. Catalyst "c" would be more suitable for use in a system containing little water. Note that the water / ethylene oxide ratio is approximately 0.55 / 1, compared to the theoretical ratio of 1/1 for the hydrolysis reaction. Catalyst "b" seems less effective when water is absent from the system (see test 2), on the other hand its activity is increased when water is present. Note that the water / EO ratio reaches practically 4/1 for this catalyst.

Although the process of the present invention is particularly useful for making ethylene carbonate, it can also be used more widely for other epoxides as we will see in the example below.

Example 3

Production of propylene carbonate

A sample of the catalyst to be tested and possibly a certain amount of water are introduced into the 130 cc Parr reactor. Samples of propylene oxide and CO 2 are introduced into the reactor cooled to -78 ° C by immersion in a dry ice / acetone bath. The reactor is then closed and placed in a bath at 36 ° C. The interior of the reactor is thus re-heated to 30 ° C, and the reaction is carried out. After an appropriate period of time, the reactor is removed from the bath and its contents are analyzed. The results of a number of tests are given in Table C below.

5

Table C

653,984

Test No

OP *

Co2 millimoles supply

H20

G * i catalyst »

Bath C

Time h

Max pressure kg / cm2

OP% conv.

Qp **

% salt.

13

20.3

1022

a 0.5511

35

21

42.6

96.2

90.3

14

20.6

1022

-

b 0.4385

36

21

34.2

60.2

25.4

15

20.2

1022

-

c 0.2401

36 •

21

56.1

85.0

58.3

16

20.4

1022

5

b 0.4382

36

21

47.3

88.2

34.6

17

20.6

1022

20

b 0.4378

36

21

52.8

89.7

56.4

18

20.1

1022

40

b 0.4386

36

21

54.2

87.4

68.3

19

20.4

1022

80

b 0.4391

36

21

62.1

91.4

82.3

* OP = ** CP =

b = c =

propylene oxide propylene carbonate tetraphenyl bromide antimony iodide dimethyl triphenyl phosphine tetraethyl amine bromide

Example 4

propylene oxide was replaced by 1-epoxy butane. The results-Production of butene-1 carbonate states of a certain number of tests are given in table D below.

The experimental protocol of Example 3 was followed, except that below.

Table D

Test No

EB *

Co2 millimoles supply

h2o

Catalyst g ***

Bath ° C

Time h

Max pressure kg / cm2

EB% conv.

BC **% select.

20

20.4

1022

-

a 0.5513

36

21

44.8

92.1

87.6

21

20.7

1022

-

b 0.4378

36

21

47.2

58.3

22.6

22

20.1

1022

-

d 0.2436

36

21

42.6

82.0

53.2

23

20.1

1022

5

b 0.4386.

36

21

51.8

89.2

40.5

24

20.8

1022

20

b 0.4392

36

21

43.8

91.4

59.8

25

20.2

1022

40

b 0.4369

36

21

56.2

93.4

72.8

26

20.6

1022

80

b 0.4381

36

21

53.6

90.8

84.3

* EB = ** BC =

b = c =

1-epoxy butane-1-butene carbonate tetraphenyl antimony bromide methyl iodide triphenyl phosphine tetraethyl amine bromide

Example 5

A sample of catalyst to be tested, a certain amount of water, and optionally of solvent are introduced into a 300 cm3 stainless steel autoclave equipped with electric chaulfation and a propeller agitator from Autoclave Engineers Inc. Samples of ethylene oxide and of CO 2 are introduced into the reactor cooled to -78 ° C. by immersion in a dry ice / acetone bath. The autoclave is then closed and brought to the desired temperature. After an appropriate period of time, the autoclave is cooled and its contents analyzed. The results of a number of tests are given in Table E below.

Table E

Test No

OE *

Supply millimoles *** co2 H20

Yjjp **

Bath ° C

Time h

Max pressure kg / cm2

OE% conv.

% salt.

27

347

1590

346

1262

60

4

52.0

95.6

97.0

28

695

2794

695

-

60

6

104.8

95.8

90.5

29

1157

2113

583

-

50

6

57.7

98.2

95.5

30

349

1590

350

1263

70

2

57.3

99.5

96.0

* OE = ethylene oxide ** THF = tetrahydrofuran

*** In each test, 20 grams of methyl triphenyl phosphine iodide were used **** 0g _ ethylene carbonate

653,984

6

The following examples demonstrate that - contrary to what has been previously admitted - it is possible to obtain high yields of alkenes carbonates at a temperature above about 90: C in the presence of large quantities of water, while avoiding that higher glycols are formed.

Example 6

Production above 90 "C and in the presence of water

A series of tests was carried out at temperatures above

The table above shows that at temperatures as high as 170 ° C, high yields of ethylene carbonate can be obtained. The amount of water present seems to have more effect at 170 ° C than at 130 ° C. In fact, the results of tests 40 and 41 suggest that one can find conditions where glycol becomes the predominant product. The C02 / 0E molar ratio was greater than 1/1 in all cases.

When the CO 2 / 0E molar ratio becomes less than 1/1, quite different results are obtained, as will be seen below.

Example 7

Effect of CO ^ OE ratio

The same experimental conditions were used as in test 33 of Example 6, except that the pressure was 25 kg / cm2, and that the CO 2/0 E molar ratio had different values between 2.0 and 0.5 . The selectivity of the conversion to ethylene carbonate (EC) was 63.2% and the selectivity of the conversion to ethylene glycol (MEG) was 36% when the CO 2 / 0E ratio was 2;

90 C in the presence of different amounts of water. Ethylene oxide, CO2. water and methyl triphenyl phosphine iodide dissolved in ethylene carbonate were continuously introduced into a 1 L pressure autoclave equipped with a heater and a stirrer; the liquid product obtained and the unreacted vapors were continuously discharged and separated in an external vapor-liquid separator. The composition of the liquid phase and that of the vapor phase were determined by gas chromatography, and the conversion rate as well as the selectivity of the reaction calculated. The results are given in Table F.

on the other hand, a selectivity for conversion to MEG of 58% and a selectivity for CE of 41% were obtained when the CO 2 / 0E ratio was 0.5. In addition, there was a significant formation of diethylene glycol (DEG), i.e. 1.4% when the CO 2 / 0E ratio was 0.5. There was only 0.8% DEG produced when the CO 2 / 0E ratio was 2. It was concluded that the molar ratio 40 CO 2 / 0E is an important factor when it is desired to produce carbonates of alkene by reaction of an alkene oxide with carbon dioxide in the presence of water and not the corresponding glycols. To achieve this, the CO 2 / 0E molar ratio must be greater than approximately 1. The most suitable CO 2 / 0E ratio will be chosen according to the amount of water present and the temperature conditions.

Example 8

Effect of partial pressure of C02

The importance of the partial pressure of CO 2 will be demonstrated by means of tests carried out according to the experimental protocol of Example 6 by varying the absolute pressure and the partial pressure of CO 2.

Test No.

Temp. ° c

Rapp. mol.

h2o / oe

Rapp. mol.

co2 / oe

Total pressure *

pco2

Mol catalyst. by oe

Food. oe mol / h / 1

% conv. oe

% salt. this

% salt. MEG

% salt. DEG

44

130

1.0

2.0

66/65

0.013

6.0

99

87.5

12.5

no

45

130

1.0

2.0

35/34

0.010

6.2

95

71.9

27.7

0.4

46

130

1.0

2.0

25 / 24.4

0.011

6.2

92

63.2

36.0

0.8

47

130

1.0

2.0

11 / 10.5

0.007

6.1

82

26.8

71.5

1.6

48

130

1.0

1.1

3.5 / 1.0

0.008

6.2

66

9.8

88.4

1.8

* Total pressure in kg / cm2; PC02 = partial pressure of C02 in kg / cm2.

Table F

Test No

Temp. CC

Rapp. mol. HzO / OE

Rapp. mol. C02 / 0E

Pressure kg / cm2

Mol catalyst. by OE

Food. OE mol / h / 1

% conv. OE

% salt. THIS

% salt. MEG

% salt. DEG

31

130

0.27

2

66

0.01

6.1

95.5

99.3

0.7

no*

32

130

0.5

1.3

66

0.012

6.5

99

96.5

3.5

no

33

130

1.0

2.0

66

0.013

6.0

99

87.5

12.5

no

34

130

1.0

1.3

66

0.014

6.8

99.5

93.3

6.7

no

35

130

1.9

2.0

66

0.010

4.0

99

74.3

23.9

1.7

36

130

2.0

2.0

66

0.002

6.1

91

66.1

30.8

3.1

37

170

0.25

2.0

66

0.0013

6.1

97

94.7

5.3

no

38

170

0.5

1.3

66

0.0022

6.4

99

72.1

26.1

1.8

39

170

0.9

1.3

66

0.002

6.8

99

48.8

46.8

4.3

40

170

1.9

2.0

66

0.0014

4.1

98

14.5

72.1

13.3

41

170

2.0

2.0

66

0.0074

4.0

98

-

92.9

7.1

42

90

0.25

4.0

66

0.013

2.0

90

94.0

5.0

0.9

43

50

0.11

4.0

66

0.005

2.0

65

94.0

4.6

1.3

* less than 0.25%

Table G

7

653,984

It can be seen that if the partial pressure of carbon dioxide is not high enough, large quantities of glycols are produced, which is contrary to the aim sought. Consequently, the temperature, the H20 / 0E ratio and the partial pressure of C02 will be adjusted to selectively obtain carbonate. For example, when the H20 / 0E molar ratio in the feed is 1/1 and the reaction temperature is 130 ° C, the partial pressure of carbon dioxide must be 65 kg / cm2 or more to obtain a optimum yield of ethylene carbonate.

Example 9

5 Effect of the H20 / 0E ratio

In other tests carried out according to the protocol of Example 6, but by changing the amount of water, the following results were obtained:

Table H

Test No

Temp. ° c

Rapp. mol.

h2o / oe

Rapp. mol.

co2 / oe

Pressure kg / cm2

Molecular catalyst by oe

Food. mol / h / 1 oe

% conv. oe

% salt. this

% salt. meg

% salt. deg

49

50

130 130

0.06 0.25

2/1 2/1

66 66

0.010 0.011

3.6 4.2

92.0 97.5

99.8 89.0

0.2 11.0

0.2

The calculation of the reaction rate constants shows that an increase in the conversion of ethylene oxide from 92 to 97.5% corresponds to an increase in the reaction rate by a factor of approximately four. So, and quite unexpectedly,

the addition of water to the anhydrous reagents considerably increases the reaction rate, while producing predominantly ethylene carbonate.

R

Claims (10)

653,984 2 1. Process for the selective production of alkene carbonate by reaction of the corresponding alkene oxide with carbon dioxide in the presence of appropriate amounts of catalyst and water, characterized in that the reaction is carried out at temperatures above 20 ° C, maintaining the carbon dioxide / alkene oxide molar ratio at 1/1 or higher, maintaining the water / alkene oxide molar ratio at 0.01 / 1 or higher. 2. Method according to claim 1, wherein the reaction temperature is greater than 90 ° C. 3. Method according to claim 2, wherein the reaction temperature is between 90 ° C and 170 ° C. 4. The method of claim 2, wherein the water / alkene oxide molar ratio is between 0.01 and 4/1. 5. The method of claim 3, wherein the water / alkene oxide molar ratio is between 0.1 / 1 and 2/1. 6. The method of claim 1, wherein the catalyst comprises at least one compound belonging to the group consisting of halogenides of quaternary amines, halides of quaternary phosphines, halides of sulfins and halides of organic derivatives of antimony . 7. The method of claim 5, wherein the catalyst is a quaternary phosphine halide. 8. The method of claim 6, wherein the catalyst is methyl triphenyl phosphine iodide. 9. The method of claim 1, wherein the catalyst content is 0.10 mole per mole of alkene oxide. 10. The method of claim 1, wherein the alkene carbonate is ethylene carbonate.