Electroanalytical Determination of Lidocaine in Pharmaceutical Preparations Using Boron‐Doped Diamond Electrodes

A new electroanalytical procedure was developed for the determination of lidocaine in commercial local anesthetics products containing lidocaine as the active ingredient. The procedure is based on the use of electrochemical methods as cyclic and square‐wave voltammetry, with boron‐doped diamond electrodes. The oxidation of lidocaine in Britton–Robinson buffer (0.1 mol L^?1) using this type of electrode gives rise to one irreversible peak in 1.68 V (versus Ag/AgCl). The detection and quantification limits obtained from pure water were 10.0 and 34.4 μg/L, respectively. The proposed electrochemical method was also successfully applied to the analysis of commercially available pharmaceutical preparations. The electrochemical responses of pharmaceutical preparations (gels) were identical to those of standard lidocaine. No influence of propyleneglycol present in the gels on the voltammetric responses was observed. Lidocaine recoveries ranged from 97.6% to 99.2%.     

Oxidative Intramolecular Coupling of Amidocuprates as a Novel Route to Amines and Hydrazines

Amidocuprates, derived from organocopper reagents and lithium amides upon exposure to oxygen at low temperature, provide new amine derivatives in satisfactory yields. Details of this flexible and simple methodology are given. The reaction mechanism is analyzed in terms of an oxidative intramolecular coupling of aminyl radicals with the ligands on Cu in the intermediate amidocuprate. This reaction is a mild and efficient method for N-alkylation, -vinylation, and -arylation by which a number of amines, not easily accessible by normal routes, can be synthesized. Once applied to lithium hydrazides, it also provides a new and straightforward entry to N-substituted hydrazines.     

Quadratic estimates for the number of integer points in convex bodies

We give bounds for the mean square deviation with respect to arbitrary probability measures of the number of integer points in translated or dilated convex bodies. The proofs are based on Fourier analytic methods.     

Contrasting chemoselectivities in the ultrasound and microwave assisted bromination reactions of substituted alkylaromatics with N-bromosuccinimide

Ultrasound and microwave assisted bromination reactions of various alkylaryls with N-bromosuccinimide, either neat or in water, shows diverse chemoselectivity. Thus, ring substitution occurs in water with ultrasound, whereas with microwaves both side-chain α-bromination and ring substitution occur. With neat reactants, side-chain α-bromination predominates for microwave assisted reactions. In the presence of water the chemoselectivity with microwave-promoted bromination is similar to that observed using classical methods.     

Synthesis and spectroscopic characterization of new triorganotin(IV) complexes with the bis(1‐methyl‐1H‐imidazol‐2‐ylthio)acetate ligand: effects on trout erythrocyte components

Triorganotin(IV) derivatives containing the anionic ligand bis(1‐methyl‐1H‐imidazol‐2‐ylthio)acetate [(S‐tim)₂CHCO₂]⁻ were synthesized from the reaction between R₃SnCl acceptors (R = Me and Ph) and the sodium salt of the ligand. Mono‐nuclear complexes of the type [(S‐tim)₂CHCO₂]SnR₃ were obtained, which were fully characterized by elemental analyses and FT‐IR in the solid state, and by NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy and electrospray ionization mass in solution. The toxic effects shown by these compounds on trout erythrocyte components showed that the toxicity of the organotin(IV) complexes depends on the nature and on the lipophilicity of the substituents on the metal centre. Copyright © 2007 John Wiley & Sons, Ltd.     

Exploring the reaction of iodine with α‐diazo esters

In this paper we describe the unprecedented reaction between α‐diazo esters 1 and iodine. The reaction, carried out in the presence of aqueous NaHCO₃, afforded the Z‐isomer of the corresponding unsaturated‐2‐iodo ester 8 . The configuration of compounds 8 was determined using the ³J_{C? H} coupling between carbonyl carbon atom and alkene proton. Mechanistic considerations accounting for the observed phenomena and including quantum chemical calculations are proposed. Copyright © 2008 John Wiley & Sons, Ltd.     

Compact sub-100-fs Nd:silicate laser

We present a compact Nd:silicate laser pumped by a single 1-W high-brightness commercial laser diode that generates pulses as short as 88 fs (nearly Fourier limited) when passively mode-locked with a saturable absorber mirror. We also tested a prismless cavity setup employing a single Gires-Tournois mirror, yielding 100-fs pulses. These setups are significantly simpler and more compact than those reported previously for short pulse Nd:silicate lasers.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Microwave Irradiation in Micro‐ Meso‐Fluidic Systems; Hybrid Technology has Issued the Challenge

A combination of microwave irradiation and flow chemistry has been described as a promising smart and hyphenated technology that can fuse and synergize the benefits of the techniques. The cells and tissues of all living organisms promote a huge number of bioorganic reactions that occur as flow systems and not the batch‐type conditions typically used by chemists and biotechnologists. Microwave‐assisted chemical conversion carried out in continuous flow mode with micro‐ or meso‐channel reactors can offer significant processing advantages, including improved thermal exchange, energy efficiency, safety, mixing control, a wider range of reaction conditions, repeatability and scalability as well as dramatic reductions in side‐reactions and degradations. This review will discuss relevant examples of organic synthesis and nanoparticles production performed in continuous flow mode with integrated microwave irradiation in micro‐ or mesofluidic systems.     

Structural insights into methyl‐ or methoxy‐substituted 1‐(α‐aminobenzyl)‐2‐naphthol structures: the role of C—H…π interactions

Aminobenzylnaphthols are a class of compounds containing a large aromatic molecular surface which makes them suitable candidates to study the role of C—H…π interactions. We have investigated the effect of methyl or methoxy substituents on the assembling of aromatic units by preparing and determining the crystal structures of (S,S)‐1‐{(4‐methylphenyl)[(1‐phenylethyl)amino]methyl}naphthalen‐2‐ol, C₂₆H₂₅NO, and (S,S)‐1‐{(4‐methoxyphenyl)[(1‐phenylethyl)amino]methyl}naphthalen‐2‐ol, C₂₆H₂₅NO₂. The methyl group influenced the overall crystal packing even if the H atoms of the methyl group did not participate directly either in hydrogen bonding or C—H…π interactions. The introduction of the methoxy moiety caused the formation of new hydrogen bonds, in which the O atom of the methoxy group was directly involved. Moreover, the methoxy group promoted the formation of an interesting C—H…π interaction which altered the orientation of an aromatic unit.