New studies in aromatic chloromethylation

Chloromethylation reactions of anisole, cumene and trifluoromethylbenzene have been examined using the reagents formaldehyde and hydrogen chloride, in the presence of an extensive range of catalysts. Reaction conditions and choice of catalyst have been optimised to obtain a high ratio of chloromethylated product: diarylmethane product. For anisole this requires the use of titanium tetrachloride as catalyst at O-5ºC; for cumene, zinc chloride as catalyst at 42-48ºC gives the best results. Trifluoromethylbenzene could not be chloromethylated using the HCI/CH(_2)O/ catalyst system. Other alkoxybenzene substrates and chloromethylating reagents have been briefly studied

Voltammetric behavior of triethylamine trihydrofluoride and anisole in acetonitrile as a first approach of studies for electro-fluorination of some adducts

This work focuses on kinetic studies of anisole and triethylamine trihydrofluoride (fluorinating agent) on platinum electrode and acetonitrile as solvent, in order to get a better understanding of their anodic behavior. Results show that both compounds can be oxidized and some kinetic parameters are calculated: the diffusion coefficient within the working media, the anodic electronic transfer coefficient and the apparent intrinsic heterogeneous electronic transfer constant. An unusual variation of these parameters occurs within the chosen reaction conditions, particularly by varying the triethylaminetrihydrofluoride concentration. Preliminary experiments for anodic fluorination of dimethoxy ethane (DME) and anisole were carried out and even if results show a possible electrofluorination for the DME (classically used as solvent), there is no fluorination of anisole when electrochemical microreactor was used

Mixed ether bath for electrodeposition of aluminum

Anisole added to the bath mixture improves Brenner aluminum plating bath technique. Mixture has lower bath vapor-pressure and the electro-deposits obtained have greater physical strength than deposits from the Brenner bath

Model arenes hydrogenation with silica-supported rhodium nanoparticles:The role of the silica grains and of the solvent on catalytic activities

Silica-supported rhodium-based nanoheterogeneous catalysts were easily prepared by impregnation with a pre-stabilized colloidal suspension. The resulting catalysts contain rhodium nanoparticles well-dispersed in the silica pores with a mean size of 5 nm. Influence of the silica grains size and of the solvent was investigated in arenes hydrogenation. It appeared that the size of the silica grains has a minimal influence on the reaction rate but the supported nanocatalysts displayed higher TOFs in hexane than in water

Extraordinary sensitivity of the electronic structure and properties of single-walled carbon nanotubes to molecular charge-transfer

Interaction of single-walled carbon nanotubes with electron donor and acceptor molecules causes significant changes in the electronic and Raman spectra, the relative proportion of the metallic species increasing on electron donation through molecular charge transfer, as also verified by electrical resistivity measurements.Comment: 15 pages, 5 figurre

Direct Detection of Products from the Pyrolysis of 2-Phenethyl Phenyl Ether

The pyrolysis of 2-phenethyl phenyl ether (PPE, C_6H_5C_2H_4OC_6H_5) in a hyperthermal nozzle (300-1350 °C) was studied to determine the importance of concerted and homolytic unimolecular decomposition pathways. Short residence times (<100 μs) and low concentrations in this reactor allowed the direct detection of the initial reaction products from thermolysis. Reactants, radicals, and most products were detected with photoionization (10.5 eV) time-of-flight mass spectrometry (PIMS). Detection of phenoxy radical, cyclopentadienyl radical, benzyl radical, and benzene suggest the formation of product by the homolytic scission of the C_6H_5C_2H_4-OC_6H_5 and C_6H_5CH_2-CH_2OC_6H_5 bonds. The detection of phenol and styrene suggests decomposition by a concerted reaction mechanism. Phenyl ethyl ether (PEE, C_6H_5OC_2H_5) pyrolysis was also studied using PIMS and using cryogenic matrix-isolated infrared spectroscopy (matrix-IR). The results for PEE also indicate the presence of both homolytic bond breaking and concerted decomposition reactions. Quantum mechanical calculations using CBS-QB3 were conducted, and the results were used with transition state theory (TST) to estimate the rate constants for the different reaction pathways. The results are consistent with the experimental measurements and suggest that the concerted retro-ene and Maccoll reactions are dominant at low temperatures (below 1000 °C), whereas the contribution of the C_6H_5C_2H_4-OC_6H_5 homolytic bond scission reaction increases at higher temperatures (above 1000 °C)

Delamination resistant composites by interleaving bio-based long-chain polyamide nanofibers through optimal control of fiber diameter and fiber morphology

In this work an innovative electrospinning system is proposed that simultaneously has an adequate temperature resistance, a high increase in mode I (þ51%) and mode II (þ96%) delamination performance and can be commercially produced. Interleaving nanofibrous veils can potentially solve the issue of the limited delamination resistance encountered in composite laminates, but industrial upscaling has always been impeded by one or more critical factors. These constraining factors include a limited temperature stability of the nanofibers, a lack in simultaneous mode I and II delamination performance increase and the complexity of the electrospinning system because non-commercial polymers or specialty nanofibers (e.g. coaxial) are required. In this paper, a robust electrospinning system is proposed that is the first to overcome all major hurdles to make nanofiber toughening industrially viable. A new class of nanofibers based on biosourced polyamide 11 and its poly(ether-block-amide) co-polymers is used to deal with those shortcomings. The nanofibers have tuneable diameters down to 50 nm and cross-section morphologies ranging from circular to ribbon-shaped. The key to this work is the fundamental underpinning of the toughening effect using a broad range of interleaves with different mechanical and thermal properties, fiber diameters and fiber morphologies, all produced from the same bio-based base polymer. Generally, round and thin nanofibers performed better than larger and ribbon-like fibers. The relationship between the fiber morphology and the delamination performance is further underpinned using detailed analysis of the fracture surface. Ultimately, this results in a range of optimized nanofibrous veils capable of improving the delamination resistance considerably without suffering from the aforementioned drawbacks

Slow, Continuous Beams of Large Gas Phase Molecules

Cold, continuous, high flux beams of benzonitrile, fluorobenzine, and anisole have been created. Buffer-gas cooling with a cryogenic gas provides the cooling and slow forward beam velocities. The beam of benzonitrile was measured to have a forward velocity peaked at 67 $\pm 5$ m s$^{-1}$, and a continuous flux of $10^{15}$ molecules s$^{-1}$. These beams provide a continuous source for high resolution spectroscopy, and provide an attractive starting point for further spatial manipulation of such molecules, including eventual trapping

Confirming the existence of π-allyl-palladium intermediates during the reaction of meta photocycloadducts with palladium(ii) compounds

The transient existence of π-allyl-palladium intermediates formed by the reaction of Pd(OAc)2 and anisole-derived meta photocycloadducts has been demonstrated using NMR techniques. The intermediates tended to be short-lived and underwent rapid reductive elimination of palladium metal to form allylic acetates, however this degradation process could be delayed by changing the reaction solvent from acetonitrile to chloroform