M. Napoli

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).

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.

DIBLOCK AND TRIBLOCK SEMIFLUORINATED N-ALKANES : PREPARATIONS, STRUCTURAL ASPECTS AND APPLICATIONS

Abstract The results of several recent studies on a new family of compounds consisting of linear semifluorinated n-alkanes with a diblock or triblock structure are reviewed. Special emphasis is laid on their morphology and structural characteristics in the crystalline state and on their phase transitions either in the solid or in the crystalline liquid state, surface activity in organic solvents and the formation of a gel-like phase. Recently proposed applications for these compounds are also reported.

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.

Experimental surface activity measurements of some fluorinated compounds in a non-aqueous medium

Abstract Surface activity of some fluorinated compounds having the structure R F R H (R F − = fully fluorinated group; R H− = fully hydrogenated group) in vaseline oil was experimentally determined by surface tension measurements at 20 °C. The surface tension vs concentration isotherms allow comparison of the behaviour of the tested compounds, particularly with regard to the relationship between surface activity and fluorinated group length of the solute.

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.

The reactions of chlorine monofluoride with unsaturated compounds and the dehydrohalogenation of some of the derivatives

Abstract The reactions of chlorine monofluoride with benzene, toluene and nitrobenzene to give monochloro derivatives has been investigated and its addition reactions to various substituted olefins studied. The products from all these reactions are consistent with the participation of a chloronium ion as the reactive species, even in solvents of low dielectric constant. The chlorofluoro addition products formed from the olefins have been dehydrohalogenated and the mechanism of reactions discussed in terms of an E1 cb mechanism or paene-carbonium ion extreme.

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 .