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Volume # 3(64), May - June 2009 — "4-(Perfluoroalkyl)iodbutanes"

Fluorine Notes, 2009, 64, 9-10

 

4-(PERFLUOROALKYL)IODBUTANES
 

A. F.Gontar, V.L.Don, E.V.Igoumnova, S.M. Igoumnov

 A.N.Nesmeyanov Institute of Organoelements Compounds RAS. 119991, Vavilova str.28, Moscow, Russia.
e-mail:
gontar@ineos.ac.ru

It has been shown earlier that perfluoroalkyliodides in the presence of radical initiators (AIBN) react with ethylene excess to form both monoadducts and products of further ethylene insertion [1,2].

In this work it has been found that monoadducts (Ia-g) at a temperature of 100-110oC in the presence of radical initiators are also able to react with ethylene to form corresponding 4-(perfluoroalkyl)iodobutanes (IIa-I) in a 40-60% yield, conversion ca. 50%.See Table 1.

RF(CH2)4I
II

BP ( oC)

Conversion, %

Yield, %

CF3 (a)

C2F5 (b)

C3F7 (c)

C3F7 (d)

C4F9 (e)

C6F13 (f)

C8F17 (g)

cyclo-C6F5 (i)

53/12 mm Hg

62-64/15 mm Hg

115/100mm Hg

72/15 mm Hg

96-97/25 mm Hg

28-30 (MP)

50-51 (MP)

93/9 mm Hg

50

54

60

64

50

42

40

48

71

63

58

55

75

32

35

38

 

The obtained 4-(perfluoroalkyl)iodobutanes (IIa-b) may be converted to corresponding alcohols.

Experimental

5-Iodo-1,1,1-trifluoropentane (IIa)
 3-Iodo-1,1,1-trifluoropropane (200g, 0.89mol) and azobisisobutyronitrile (AIBN, 3 g) are fed in a steel rotating autoclave (0.5L water capacity) equipped with a needle valve. The autoclave is pressurized, ethylene is fed to attain a pressure of 45 atm, the autoclave is heated to a temperature of 110oC and kept for another 4 hours. Then it is cooled to room temperature, the ethylene excess is released through the needle valve and the liquid is discharged in a flask. The non-reacted 3-iodo-1,1,1-trifluoropentane is distilled from the reaction mass at a boiling temperature of 90-95oC (80g), the residue is distilled under vacuum at a boiling temperature of 50oC/10 mm Hg collecting fractions. 90g of the crude material is collected. After rectification 80g of 5-iodo-1,1,1-trifluoropentane (IIa) of 97% purity remains, BP 153oC, 71% yield, 50% conversion. Another 4-(perfluoroalkyl)iodobutanes (II b-i) are obtained in a similar way ( see Table 1).

5,5,5-Trifluoropropenpentan-1-ol (IIIa)
N-Methylpyrrolidone (500mL), water(30g, 1.66 mol) and 5-iodo-1,1,1-trifluoropentane (175g, 0.69 mol) are placed in a three-neck flask ( 1 L water capacity) fitted with a thermometer, stirrer and backflow condenser. The reaction mass is heated up to 120oC and mixed at this temperature for 20 hours. After cooling the reaction mass to room temperature the backflow condenser is replaced for a direct one and all volatile products are distilled in vacuum of a water-jet pump. The distillate is poured into 1L of 15% hydrochloric acid. The obtained solution is extracted with ether (3X250mL). Ether extracts are dried over MgSO4 , ether is distilled, the residue is distilled under vacuum to yield 50g of crude product containing 80% of 5,5,5-trifluoropentan-1-ol. After rectification 30g of 5,5,5-trifluoropentan-1-ol (IIIa) of 99% purity is produced in 30% yield , BP 73oC/ 30 mm Hg.

5,5,6,6,6-Pentafluorohexan-1-ol (III b)
 6-Iodo-1,1,1,2,2,2-pentafluorohexane (183g,0.61 mol), N-methylpyrrolidone (780 mL) and water ( 34g, 1.89mol) are placed in a three-neck flask ( 2 L water capacity) fitted with a mechanical stirrer, thermometer and a backflow condenser. The mixture is heated up to a temperature of 140-145oC and is stirred for 20 hours at this temperature. Then the backflow condenser is replaced by a direct one, the organic layer is separated, washed with water, dried over MgSO4 and distilled. There is obtained 20 g of 6-iodo-1,1,1,2,2,2-pentafluorohexane that is returned to the synthesis and 65g of 5,5,6,6,6-pentafluorohexan-1-ol ( 30g of 93% purity and 35 g of 96.5% purity). The yield is 63% ( taken into account conversion).

References

1. W.R. Dolbier. Chem. Rev. 1996,96,1557-1584.

2. N.O. Brace. Journal of Fluor. Chem., 93 (1999) 1-25.


Fluorine Notes, 2009, 64, 9-10

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