Lino Conte

The electrochemical fluorination of organic compounds: Further data in support of the ECbECn mechanism

Abstract Data in support of the four-stage mechanism ECbECN result from the electrochemical fluorination of some acyl halides (benzoyl, n-butyryl and iso-butyryl, benzenesulphonyl and p-toluenesulphonyl chlorides) and amines (tripropylamine and N-methylmorpholine).

Synthesis and characterization of a new class of polyfluorinated alkanes: tetrakis(perfluoroalkyl)alkane

Abstract The synthesis and physico-chemical characterization of 1,1,2,2-tetrakis(perfluoroalkyl-methylene)ethane {[F(CF 2 ) n CH 2 ] 2 CH} 2 ( n =6, TK6 ; n =8, TK8 ) are reported. The synthesis consists of four steps: (1) addition of allyl alcohol to a perfluoroalkyl iodide, F(CF 2 ) n I ( n =6,8) to give the corresponding iodo-adduct; (2) dehalogenation of the adduct by treatment with zinc in aqueous acetic acid, yielding 3-perfluoro- n -alkyl-1-propene; (3) addition of 3-perfluoro- n -alkyl-l-propene to perfluoroalkyl iodide, F(CF 2 ) n I ( n =6,8) to give 1,3-perfluoro- n -alkyl-2-iodo-propane; (4) coupling of 1,3-perfluoro- n -alkyl-2-iodo-propane by zinc in acetic anhydride giving the final products. TK6 and TK8 are characterized by very low surface tension values and exhibit very good properties as potential ski-waxes.

Liquid-phase fluorination of aromatic compounds by elemental fluorine

Abstract The fluorination of aromatic compounds (benzene, toluene, phenol and benzoic acid) by elemental fluorine diluted with nitrogen has been investigated in various solvents (Freon 11, chloroform, methanol, trifluoroacetic acid, 2,2,2-trifluoroethanol, water) in order to define the influence of the experimental conditions on the reaction. Experiments have been carried out by varying the temperature, the substrate concentration in solution, the molar ratio of fluorine to substrate, and the concentration of fluorine in the fluorine/nitrogen mixture. In all cases, the effects on the yield of fluorinated products were studied. Monofluorinated compounds were mainly found in the reaction mixture, the isomers formed being in accord with the mechanism for electrophilic substitution. The highest yield of monofluorinated products was obtained with polar solvents and the following order was found: CFCl 3 3 3 OH 3 CH 2 OH 3 COOH. Interesting results were also found using particular additives (for instance, KOH or C 4 F 9 SO 3 Na in methanol) or water as the solvent. A direct relationship was observed between the yield of monofluorinated compounds and the molar ratio of fluorine to substrate, which has to be less than one in order to obtain high yields. In contrast, low selectivity, expressed as the yield ratio of ortho to para (or meta ) isomers, was found.

Electrochemical production of partially fluorinated organic compounds: N-methylmorpholine fluorination

Abstract The usual electrochemical fluorination of organic compounds in anhydrous HF produces completely fluorinated materials. In order to obtain partially fluorinated compounds, electrofluorination has been conducted under various conditions, including the use of solvents. None of the solvents lead to satisfactory results. Experiments have also been carried out with high concentrations of N-methylmorpholine in anhydrous HF and they have provided information about the selectivity and the mechanism of the reaction. Various partially fluorinated derivatives of N-methylmorpholine have been identified, and some of them separated from the reaction mixture.

Effect of reaction conditions on the radical addition of perfluorohexyl iodide to vinyl acetate

Abstract The radical addition of perfluorohexyl iodide to vinyl acetate to give an iodine-containing adduct has been studied under different conditions in order to define their influence on the reaction. Experiments have been carried out varying parameters (molar ratio of reagents, weight percent of initiator, reaction time, temperature, oxygen removal) and studying the effects on the perfluoroalkyl iodide conversion and on the adduct yield. From the experimental data obtained, the conditions required to optimize the adduct yield have been defined.

Preparation of chloropentafluoroethane from dichlorotetrafluoroethane - note 1.

Abstract Gaseous fluorination with hydrogen fluoride at atmospheric pressure of the two isomers CClF 2 CClF 2 and CCl 2 FCF 3 was carried out continuously on a chromic oxide based catalyst. The fluorinated derivative, obtained in a yield greater than 90%, was chloropentafluoroethane. Hexafluoroethane and an isomeric mixture of trichlorotrifluoroethane were obtained as by-products. The latter was recycled with unconverted C 2 Cl 2 F 4 for further fluorination. Both conversion of C 2 Cl 2 F 4 and selectivity to the formation of C 2 ClF 5 were affected by temperature, contact time and molar ratio of the reagents. The catalytic activity of chromic oxide was adversely affected by small amounts of water in the hydrogen fluoride. A difference was also observed in the reactivity of the two isomersCCl 2 FCF 3 and CClF 2 OClF 2 The formation of C 2 Cl 3 F 3 as a by-product was due to the disproportionating activity of chromic oxide upon C 2 Cl 2 F 4 .

Electrochemical fluorination of 4-(perfluoro-n-butyl)-n-butanoyl chloride

Abstract Electrochemical fluorination of 4-(perfluoro-n-butyl)-n-butanoyl chloride produces perfluorooctanoyl fluoride in higher yields than those obtained from n-octanoyl chloride, which is the usual starting material. In particular, one of the by-products of the industrial process, the cyclic perfluoroether perfluoro-2-propyl-tetrahydropyran, is not formed. Also the other by-products. except fluorocarbon perfluoro-n-heptane, are produced in lower amounts. These results are discussed and a mechanism is suggested.

Correlation between yield and operating conditions in the electrochemical fluorination of tripropylamine

Abstract Electrochemical fluorination of tripropylamine in anhydrous hydrogen fluoride was studied in order to verify the correlation between the operating conditions and the yield of the corresponding perfluoroamine. The parameters tested were: temperature, voltage, initial concentration of amine in the bath, constant concentration of amine in the bath and stirring effect. Experimental data show that temperature is the parameter exerting the most remarkable influence over perfluoroamine yield and by-products formation.

A MODIFIED PROCEDURE FOR PREPARING PERFLUOROALKYL ACETIC ACIDS FROM PERFLUOROALKYL IODIDES

Abstract Perfluoroalkyl acetic acids, R F CH 2 COOH, can be prepared in several ways. Particular attention is here paid to the method starting from the azonitrile-initiated addition of the corresponding perfluoroalkyl iodide, R F I, to vinyl acetate, CH 2  CHOCOCH 3 , with formation of the adduct R F CH 2 CHIOCOCH 3 . This method is reported as a four-step process that synthesizes perfluoroalkyl acetic acids through the conversion of the adduct into the corresponding ester R F CH 2 CH 2 OCOCH 3 and alcohol R F CH 2 CH 2 OH. A simplified procedure consisting of three steps is also suggested: starting from the same reagents, perfluoroalkyl acetic acids can be easily prepared by the oxidation of the corresponding aldehyde R F CH 2 CHO obtained directly in good yields by acid hydrolysis of the primary adduct R F CH 2 CHIOCOCH 3 .

Synthesis of F(CF2)8(CH2)8H and gel phase formation from its solutions in homologous alcohols

Abstract The behavior of F(CF 2 ) 8 (CH 2 ) 8 H in methanol, ethanol and propanol with reference to the gel phase formation of diblock semifluorinated n -alkanes was investigated. Samples with different degrees of purity employing different volumes of solvent were studied in order to ascertain the influence of the process variables on the gel phase formation. For each alcohol the volume leading to the best result was determined and the relative values were compared in order to evaluate the effectiveness of this treatment as a purification method for these semifluorinated compounds. The synthesis of F(CF 2 ) 8 (CH 2 ) 8 H was also studied with reference to the influence of ratio of reactants and temperature on the addition of the fluorinated reactant to the 1-olefin.