Ph.D., Ziyadullayev O.E., masters Ergashev Yo.T.

Tashkent Chemical Technological Institute, Uzbekistan

THEORETICAL ABC OF GAMOGEN-CATALYTIC VINYLATION REACTION OF AROMATIC ACETYLENE ALCOHOLS

 

Recently, scientific investigations on the creation of ecological safety and waste less technologies, also,  on the synthesis of economically cheap chemical preparations with higher yield  and to introduce them into the practice have been carried out [1, 2].

Hence, vinylation reaction  on the basis of aromatic acetylene alcohols (AAÀ) acetylene with higher base-catalytic system, The scheme of the reaction has been offered as following [3, 4]:

here; R= -H, RI= -C6H5; R= -CH3,  RI= -CH3; R= -CH3, RI= -C2H5; R= -CH3,

RI= èçî -C3H7, R= -CH3, RI= -C(ÑH3)3; R= -CH3, RI= -Ñ6H3, Ph= C6H5.

 

Gamogen-catalytic vinylation reaction on the basis of AAÀ MeOH-DMSO (MeOH- LiOH, NaOH and KOH) has been carried out and it was exposed that vinyl ethers (VE) synthesized desirable in the interval of 40-60% [4].

It has been observed the relatively maximum yield synthesis of AAÀ VE in the presence of MeOH-CsF-DMSO with higher base-system on the experiment's results.

Table 1

The influence of nature and temperature of catalysts on the yield of AAÀ VE

(duration of reaction is 6 hours, solvent DMSO)

Catalyst

Temperature, oC

I

II

III

IV

LiOH·CsF

80

44,3

38,2

33,3

56,0

100

49,0

46,6

42,9

59,4

120

51,1

48,4

46,3

58,0

KOH·CsF

80

49,6

45,2

40,2

57,4

100

57,4

52,0

40,7

66,4

120

58,3

55,7

49,6

67,3

NaOH·CsF

80

74,2

73,2

67,3

79,6

100

84,8

77,1

72,3

88,0

120

86,0

79,7

75,0

89,5

here: I- VE 1-Fenil-3-metilpentin-1-ol-3;

II- VE 1-Fenil-3,4-dimetilpentin-1-ol-3;

III- VE 1-Fenil-3,4,4-trimetilpentin-1-ol-3;

IV- VE 1,3-Difenilbutin-1-ol-3.

 

The gained results show that as LiOH, NaOH and KOH are used in the system of CsF-MOH-DMSO as MOH, in each particular state the yield of product goes through maximum while the temperature is rising. It has been determined the increase of AAÀ on the series LiOH·CsF < KOH·CsF < NaOH·CsF in the selected catalytic systems. As temperature rose from 80 to 120 oC, the yield raised appreciably.

The selectivity of temperature 100 oC state has been meant as the highest system for the process.

It can be explained that catalytic activity of presented system with the formation of CsOH and NaF in the system and its less solubility with the higher base-property of CsOH. In LiOH and KOH systems, the solubility of the formed LiF and NaF is higher, and in the system they are existed in the state of ion in the system, the balance specifies. Hereon, CsOH couldn't perform completely activity. Owing to this LiOH+CsOH+LiF+CsF system is in charge of catalyst.

It has been observed, vynilation process on the AAÀ higher base-system, reaction undergoes under top level along with the formation of polycomponent mixtures on the some stages. Herein, moving hydrogen of acetylene goes on base of stereo-regioselectivity, also its exchanging process does easily. Although investigations on the vinylation process of organic compounds including members of various classes hydroxyl group containing in their molecules have been carried out for years, reaction mechanism hasn't enough researched scientifically yet. At present having formed catalytic active center, reactions being carried out in the system MeO-CsF-DMSO, formation of metal solvates and having become interval metal complex possessing active center, counterbalances the function of catalyst.

As the result of investigation, it has been determined that duration of reaction appreciably influences on the product yield. Including when the process lasted for 6 hours, it was observed vinyl ethers emerge with top yield in all selected systems.

When the process lasted 8 hours, it was observed the yield of product decrease on the consequence of polycomponent mixtures formation, dimerization of acetylene and polimerization of VE (Table 2).

Table 2

The influence of nature and temperature of catalysts on the yield of AAÀ VE

(Temperature 100 oC, solvent DMSO)

Catalyst

 

Duration of reaction, hour

I

II

III

IV

LiOH·CsF

4

43,8

39,0

36,8

54,8

6

49,0

46,6

42,9

59,4

8

42,4

37,8

34,1

52,2

KOH·CsF

4

48,4

46,3

44,4

62,0

6

57,4

52,0

47,0

66,4

8

47,2

42,2

40,1

58,4

NaOH·CsF

4

78,2

73,0

67,7

79,8

6

84,8

77,1

72,3

88,0

8

73,4

70,8

65,5

76,3

 

It has been determined that the yield of product emerge at very maximum: I=84,8%; II=77,1%; III=72,3% and IV=88,0% in the interval of catalysts LiOH·CsF, KOH·CsF as NaOH·CsF is used. We can explain the exact higher yield of VE quantity in NaOH·CsF state than in KOH·CsF state as stated below:

- as the result of fusing of sodium hydroxide in DMSO solution, exchanging reaction with CsF goes to the end , forming CsOH quantity relatively more, forms metal complex possessed active catalytic center and it just reacts with acetylene easily;

- new higher state is observed  in potassium hydroxide too, but formation of potassium and cesium alcoholates two kinds of catalysate have been formed in the system of AAÀ active centre, in the account of being difficult to separate them from each other, quantity of additional products form relatively more, and this demands extra product alongside with complication of acetylene combination. As a result, in order to increase the yield of product it leads to continue the process longer, to use extra acetylene and solvent, to increase economical expense. For these reasons the cost of VE rises in price;

- Because of being higher of the solubility degree of KF than NaF, having formed interval compound with DMSO, KF causes quantity of CsOH to be less.

Conclusion, in order to synthesize AAÀ VE with higher yield - 6 hour's process at 100 oC temperature in the system of NaOH-CsF-DMSO has been chosen. In this case it has been determined that very maximum yield of product is I=84,8%; II=77,1%; III=72,3% and IV=88,0%.

Literature:

1. Temkin O. N. Acetylene chemistry: “Acetylene tree” in organic synthesis on the eve of xxi century // Journal Sorosov of science. Ò.7., ¹6, 2001. p. 32-46.

2. Schelkunov S.À., Sivolova À.Î., Ìàtàåvà S.Î., Ìinbaev D.B., Ìuldakhmedov Z.Ì. // Journal of organic chemistry. 2001. Ò.37. V. 1. p. 17-20.

3. Belov B.I., Êozlov V.V. // Success of chemistry, 1963. Is. 32. ¹ 2. p. 121-153.

4. Yunusov R.Yu. Organic chemistry. Òàshkent.: Uzbekistan, 1995. V. 1. p. 725.

5. Ziyadullaev O.E. Synthesis and technological of aromatic acetylenic alcohols, their vinyl ethers on the base of phenylacetylene: des. cand. chem. sc. Tashkent. 2011. p. 213.