Frédéric Gohier

In Situ Formation of Diazonium Salts from Nitro Precursors for Scanning Electrochemical Microscopy Patterning of Surfaces

Give me a tip: In situ production of diazonium salts from nitro compounds allows the use of diazonium chemistry for microelectrochemical patterning of surfaces by scanning electrochemical microscopy. The nitro precursor is reduced at the tip to the amine, which is diazotized in the interelectrode space as it diffuses (see picture). The tip acts as a source of diazonium salts, allowing sample derivatization just beneath the tip.

Synthesis of N-Aryl and N-Alkyl Anthranilic Acids via SNAr Reaction of Unprotected 2-Fluoro- and 2-Methoxybenzoic Acids by Lithioamides

Substitution of the fluoro or methoxy group in unprotected 2-fluoro- and 2-methoxybenzoic acids to afford N-aryl and N-alkyl anthranilic acids occurs upon reaction with lithioamides under mild conditions in the absence of a metal catalyst.

Ortholithiation of Unprotected Benzoic Acids: Application for Novel 2‐Chloro‐6‐Substituted Benzoic Acid Syntheses

Abstract 2‐Chloro‐6‐substituted benzoic acids of the type 2a–h were prepared by the tandem metallation sequence from 2‐chlorobenzoic acid 1 with the 1:1 complex sec‐butyllithium/TMEDA in THF at −78°C followed by quenching with electrophiles.

Compatibilization of NR/EVA blends by natural rubber grafted poly(dimethyl(methacryloyloxymethyl)phosphonate) compatibilizer

Abstract Graft copolymer of natural rubber (NR) and poly(dimethyl (methacryloyloxymethyl) phosphonate (PDMMMP) (i.e., NR-g-PDMMMP) was prepared and used as a blend compatibilizer in 50/50 NR/EVA simple blends. Influence of various loading levels of NR-g-PDMMMP (i.e., 0, 1, 3, 5, 7, 9, 12 and 15 wt% of NR) on rheological, dynamic, mechanical and morphological properties was investigated. The results showed that the best compatibilization effect was observed in the blend with a loading level of NR-g-PDMMMP at 7 wt%. That is, the highest complex viscosity, tensile strength, elongation at break as well as the lowest values of tension set and tan δ value (i.e., damping factor) were observed. This indicates the highest mechanical strength and the supreme elastic response of the material. Morphological properties of 50/50 NR/EVA blends with any loading levels of NR-g-PDMMMP compatibilizer showed co-continuous phase system. However, in the NR/EVA blend with NR-g-PDMMMP at a loading level of 7 wt%, the finest phase morphology was observed. The 50/50 NR/EVA blend with lower and higher loading amounts of NR-g-PDMMMP compatibilizer exhibited inferior dynamic, mechanical properties as well as larger phase morphologies.

Preparation of New Polyols Based on Cis-1,4-Polyisoprene by Using 1,3-Dipolar Cycloaddition

This research focuses on synthesis and modification of polyol precursors derived from cis-1,4-polyisoprene (PI). These new polyol precursors can be converted to high value-added polyurethane (PU). The epoxidized hydroxytelechelic PI (EHTPI) prepared by chemical modification from PI was used as starting material for polyol synthesis. 1,3-Dipolar cycloaddition between a terminal alkyne and an azide has rapidly become the most popular click reaction. We applied this reaction to couple azide-functionalized PI and alkyne-functionalized sugar for preparing polyols. For azide functionalization, 1-methyl epoxidized cyclohexane was used as a model molecule, and various conditions for epoxide ring opening of 1-methyl epoxidized cyclohexane and EHTPI were investigated. The cycloaddition of alkyne and azide was carried out in the presence of sodium ascorbate and copper sulfate. The polyol precursors obtained might be used to prepare biodegradable polyol PU.