Ahmed Baklouti

MEASUREMENT OF THE OPTICAL PURITY OF FLUORINATED COMPOUNDS USING PROTON DECOUPLED 19F NMR SPECTROSCOPY IN A CHIRAL LIQUID CRYSTAL SOLVENT

The use of trifluoroacetic anhydride as an achiral derivatizing agent for enantiomeric excess measurement through chiral liquid crystal NMR is described. Examples involving amines, amino acids and alcohols are provided. It is shown that the proton decoupled fluorine NMR spectra of the -CO-CF3 group allow good enantiomeric discrimination based on both the chemical shifts and the dipolar splitting. The spectra separation is due to the differential ordering effect of enantiomers in the oriented chiral solvent. The results are then compared to the discriminating power of the -CO-CD3 group that has been previously described using deuterium NMR in the same anisotropic medium.

Dimercaptoethane oxirane ring opening reaction: β,β′-dihydroxy dithioether synthesis

Abstract The action of dimercaptoethane on alkyl oxiranes in the presence of benzyltrimethylammonium hydroxide (Triton B) allows, via regiospecific opening reaction, the preparation of the corresponding β,β′-dihydroxy dithioethers in excellent yields.

Synthèse de carbamates fluorésNsulfonylés

Abstract Fluorinated N sulfonyl carbamates were synthesized in good yields by action of fluorinated alcohols on aroxysulfonyl carbamates. The reaction takes place in ether at room temperature or more rapidly in chlorobenzene at 130 °C.

N-Bromosuccinimide-dimercaptoethane cobromination of alkenes: synthesis of β, β'-dibromodithioethers

Abstract Alkenes react in diethyl ether with N -bromosuccinimide (NBS) and dimercaptoethane to afford the corresponding β,β′-dibromodithioethers. Bromine and dimercaptoethane are added to the aliphatic terminal olefins in an anti-Markovnikov fashion.

Synthesis of fluorinated aroxysulfonyl ureas

Abstract The addition of 2,2,2-trifluoroethylamine (CF3CH2NH2) in toluene and F-alkylamines (C6F13(CH2)2NH2 and C4F9(CH2)2NH2) without solvent to aroxysulfonyl isocyanates is a good method for preparing fluorinated aroxysulfonyl ureas. The yield of the reaction is high.

Synthesis and surface properties of semi-fluorinated gemini surfactants with two reactive bromo pendant groups

This paper presents a series of semi-fluorinated gemini surfactants with two bromo pendant groups. It reviews the effect of the number of methylene units in the spacer group between the two hydrophilic quaternary ammonium heads. Critical micelle concentration (cmc) and free energy of micellization (ΔG(M)(0)) of the title surfactants, in aqueous solution, have been investigated as a function of the number n of carbon atoms in the hydrocarbon spacer. We have pointed out a different behaviour as compared to Gemini hydrocarbon homologues. In the present study, when the number of methylene units (n) in the spacer increases, the cmc first decreases and reaches an optimum for (n=6), then it increases linearly from n≥6. Variations of cmc have been interpreted in terms of conformation changes of the surfactant ion and progressive penetration of the alkyl chain spacer in the micelle hydrophobic core. In this series, the increase of the hydrophobicity seems not to favour the micellisation process as expected, probably impacted by the mutual phobicity of the perfluorinated tails and the hydrocarbon spacer. A minimum is reached for a spacer with six methylene units which seems to be the optimal conformation. The free energy of micellization (ΔG(M)(0)) confirm this tendency.

F-alkylation of bis(allyl) polyoxyethylene ethers

Abstract Bis(3- F -alkylallyl) polyoxyethylene ethers were obtained via radical addition of F -alkyl iodides on bis(allyl) ethers CH 2 CH(CH 2 OCH 2 ) n CHCH 2 followed by 1,8-diazabicyclo[5.4.0]undec-7-ne (DBU) dehydrohalogenation.

Bromofluorination of bis(allyl)polyoxyethylene glycol ethers

Abstract The bromofluorination of bis(allyl)polyoxyethylene glycol ethers has been achieved by action of N -bromosuccinimide/triethylamine tris-hydrogenfluoride. For the starting 2-methylallyl ethers, the addition reaction is regioselective and only tertiary fluorine adducts were observed. Under the same conditions a mixture of addition and degradation products was observed from the nonbranched bis(allyl) ethers.

Synthesis of F-alkyl α-hydroxy acids and esters from F-alkyl epoxides and F-alkyl α-bromo acids and esters from F-alkyl bromohydrins

Abstract F-alkyl α-hydroxy acids and F-alkyl α-bromo acids were prepared respectively by the nitric acid ring-opening oxidative reaction of F-alkyl oxiranes, and oxidation by chromic acid of F-alkyl bromohydrins. The synthesized acids were converted to the corresponding methyl esters which may prove to be useful in the synthesis of F-alkylated heterocycles.

Synthesis of Bis (Cyclic Dithiocarbonates) Bridged by a Polyoxyethylene Chain

The reaction of bis-oxiranes 1 with carbon disulfide in the presence of lithium bromide as catalyst at reflux in dichloromethane affords selectively the corresponding polyoxyethylene bis (five-menbered cyclic dithiocarbonates) 2 in good yields. On the basis of the reaction conditions, an oriented mechanism for the reaction is proposed.