SU1754700A1 - Method of secondary polyfluoroalkyl-containing alcohols synthesis - Google Patents

Abstract

The essence of the invention: the product is secondary polyfluoroalkyl-containing alcohols of general formula: X (CF2) n-CH (OH) - R2, where, F; R2-C2-8 alkyl; n 1-6. The yield is 76-84.7%. Reagent 1: polyfluorocarboxylic acid ester of the general formula: X (CF2) n - C (OH3R3. Where Rs is Ci-Ca is alkyl. Reagent 2: trialkylaluminum. Reaction conditions: in dichloromethane, in an inert gas flow, when cooled: 1 tab. & IS n -1-6; R2 C2H5-CeHi7, which can be used as solvents for polymers, starting compounds in the synthesis of asymmetric fluorinated ketones, intermediate products for the synthesis of biologically active substances, monomers for polymerization and copolymerization, surface-active substances, 4J O 4b xj O O

Description

as components of solid rocket fuel in other areas of technology,

A known method of producing alcohols (I) alcohols by the interaction of fluorinated esters of the formula (II) with metal-5 organics, which are alkyl magnesium halides (Grignard reagents). Here, the secondary alcohols of formula (I) are formed in a mixture by tertiary alcohols of formula (111). In a number of 10 rays, the tertiary alcohols of formula (II) are the main products of the reaction.

-

R, COOR3 + R2MgHa1- RrCH-R RrC-R3

I o

IIOHON

1 III

where RI is CPH;

Rs — Me, Et;

R2 - Me, Et, Pr; 20

Br, J.

There is a method according to which the interaction of the fluorinated ester with Grignard reagents produces exclusively fluorinated 25 ketones (IV), the reduction of which produces alcohols of formula (I);

C2F5COOЈt + R2MgHat- C2F5-C-R2 LIV O30

NQBH with -CH-Ra

OH I

The closest to the proposed method is the preparation of alcohols of the formula I) by the interaction of esters with a mixture of isopropyl magnesium bromide and methyl or ethyl magnesium bromide. The reaction is carried out with a mixture of metal (ethyl) magnesium diide and iso-40-propyl magnesium bromide, which is obtained directly before the reaction from magnesium, methyl iodide and isopropyl bromide. Process conditions are standard for Grignard synthesis. The process is conducted in a current of inert 45 high-frequency gas. Immediately before use, the solvent and reagents are thoroughly cleaned from traces of compounds containing an active hydrogen atom: water, alcohols, primary and 50 secondary amines, etc. The solvent is usually diethyl ether. In some cases, dipropyl, diisoyl ethers, dioxane and tetrahydrofuran are used. However, diethyl ether is the best solvent for magnesium-organic compounds. The solution is a reaction product; it releases the surface of magnesium, which makes it possible to further proceed.

The preparation of the organomagnesium compound is carried out as follows.

Magnesium is placed in the flask. The flask is thoroughly heated with an open flame of the burner to remove moisture adsorbed on the surface of glass and metal. The flask is then cooled and a small amount of alkyl halide and absolute diethyl ether is added. At the end of the vigorous reaction, the remaining solution of alkyl halide in ether is added. At the same time, in order to avoid side reactions, the alkyl halide is dissolved in a large amount of solvent (it is taken in such an amount that at the end of the reaction 1-2 mol of organomagnesium compound is contained in 1 l of solution) and added at a minimal rate, and the reaction mass is vigorously stirred.

The organomagnesium compound mixture is filtered through a glass filter using nitrogen pressure, cooled in a dry ice bath, and the ester added dropwise with vigorous stirring. The mass is then hydrolyzed with a 10% solution of sulfuric acid, the ether layer is separated and dried. The ether is distilled off, the residue is distilled. The yield of secondary polyfluoroalkyl-containing alcohols is 49- 68%.

The disadvantages of this method are the moderate yield of the target product (49- 68%), the ambiguity of the reaction (as a rule, the products of interaction of fluorinated esters with both methyl or ethylmagnesium iodide and isopropyl magnesium bromide are formed). The method is feasible only under laboratory conditions, since organomagnesium compounds are not industrial products. It is necessary to use flammable and explosive diethyl ether.

The aim of the invention is to increase the yield of the target products and the selectivity of the process.

The goal is achieved by the interaction of polyfluorocarboxylic acid esters of the formula

.BUT

R, -SR &

where Ri has the indicated values, with an organometallic compound in a stream of inert gas in an organic solvent medium while cooling and separating the target product, the trialkyl aluminum being used as the organometallic compound and dichloromethane as the organic solvent.

The method is carried out according to scheme 1 as follows:

С + AID OR, з -200О + 20 ° С

ioa

R | -CH-R2

i HE

I ah

where Ri is HCF2 (a), CF3 (6), H (cF2) 2 (v, d), CeFta

(g);

R2 - C2Hv (a.b.c), SaNp;

R3-Me, Et.

To a solution of trialkylaluminum in absolute dichloromethane cooled to (-15) - (20) ° C, a solution of polyfluorocarboxylic acid ester in absolute dichloromethane (argon current) is added dropwise with stirring. Stir for 30-40 minutes, bring to room temperature and leave overnight. The mixture is cooled to 3–5 ° C and ethanol is added dropwise, then the calculated amounts of water and 20% sulfuric acid solution. The lower organic layer is separated, the aqueous layer is extracted with dichloromethane. The extracts are combined, dried over MgSO4 and the desired product is isolated by distillation.

The structure of the obtained secondary polyfluorinated alcohols (I) was confirmed by IR and PMR spectroscopy.

Example 1. To a solution of 17.1 g (0.15 mol) of triethylaluminium (TEA) in 100 ml of CH2CI2 cooled to -20 ° C, a solution of 5.6 g (0 , 05 mol) of difluoroacetic acid ethyl ester in 30 ml of CH2CJ2. Stir for 30 minutes, bring to room temperature and leave overnight. Then, at 5 ° C, 10 ml of ethanol is added dropwise, then 50 ml of water and 50 ml of a 20% solution of sulfuric acid. The lower organic layer is separated and the aqueous layer is extracted with ether. The MgSO4 is dried and distilled; the fraction is collected with a bp. 85-86 ° C. 4.2 g (76%) of 1,1-difluorobutanol-2 are obtained.

IR spectrum, v 3380 br (OH).

PMR spectrum d, ppm: 1.2 t, J CH 3 —CH 2 7.3 Hz, 3N (CH 3); 1.41-1.80 m, 2H (CH2); 3.56- 3.77 m, 1H (-CH-); 4.69 s, 1H (OH); 5.61 etc JHCFg 56 Hz, JHCFaCH-4 Hz, 1H0HCF2).

PRI mme R 2. Similarly to example 1, out of 34.81 g (0.3 mol) of tea and 16 g (0.1 mol) of methyl 2,2,3,3-tetrafluoropropionic acid, 13 g (81%) are obtained. ) 1,1,2,2-tetraf-torpentanol-3 st. Boil 166 ° C.

IR spectrum v: 3300 br (OH). HLR spectrum (d ppm): 1.07 t (3N, CH 3, J 7.3 Hz); 1.5-1.67 m (1H, -CH2-); 1.7-1.88 m (1H-CH2-); 3.55 s (1H, OH); 3.77-4.94 m (1H- 5 CH-); 5.97 th.t. (1H; HCF2CF2).

Froze Analogously to example 1, out of 9.1 g (0.08 mol) of TEA and 10.2 g (0.027 mol) of perfluoro-enanthic acid methyl ester, 8.64 g (84.7%) of 0,1,1,2,2,2 are obtained, 3,3,4,4,5,5,6,6-t of ridecafluorononol-7. Bp 78-80 ° C / 20 mmHg IR spectrum, v 3350 br (OH). PMR spectrum d, ppm : 1.07 t (3N, CH3; JcHjCH, -8 Hz); 1J3 to (2N.-CH2-). 2.7 s (1H, 5 OH); 3.82-4.24 m (1H, CH).

EXAMPLE 4 Analogously to example 1, of 41.5 g (0.1 mol) of trioctylaluminium and 5.4 g (0.033 mol) of methyl methyl 2,2,3,3-tetrafluoropropionic acid, 6.2 g of 0 are obtained. (77.5%) 1,1,2,2-tetrafluoro-decanol-3, b.p. 84-85 ° / 2 mmHg PMR spectrum, d ppm: 1.03-1.63 m, 17H (CSH1); 3.25-4.25 m, (2 N.-CH-. OH); 5.99 etc. (JHCF2 53.75, JHCFaCF 8.2, JHCFaCF 2.8 Hz), 5 1H (HCF2).

A comparison of the proposed and known methods is given in the table.

Claims (1)

The proposed method allows to increase the yield of the target products from 48-68 to 0 76-84.7%, provides the selectivity of the process, allows you to exclude fire and explosive diethyl ether from the process, based on reagents produced by the industry. 5 claims The method of obtaining secondary polyfluoroalkyl-containing alcohols of the formula RrCH-R2 0ON where RI is X (CF2) n, where X is H, F, n is 1-6; R2-C2H5-C8H17, by reacting a polyfluorocarboxylic acid ester of the formula five S / ABOUT Ri-C - OR3. where RI have the indicated meanings; R2 - CH3 or C2Hs, with an organometallic compound in the current 0 inert gas, in the environment of an organic solvent while cooling and evolving a: left product, characterized in  that, in order to increase the yield of the target product and the selectivity of the process, trialkyl uMine was used as the organometallic compound, and dichloromethane was used as the organic solvent. Comparison of methods for the preparation of secondary polyfluorinated alcohols of the formula Rf-CH-Rz HE 1st qFs Cxhf 48 Forms) - “JE) 1