Novel Synthesis of Mafenide and Other Amino Sulfonamides by Electrochemical Reduction of Cyano Sulfonamides

Both aliphatic and aromatic amino sulfonamides such as mafenide ( 1a ) were synthesized in good yields (80–86%) by direct electrochemical hydrogenation of the corresponding nitriles in an undivided cell containing a Ni cathode, a Pt anode, and Raney Ni as catalyst (Table 1). The reaction can be performed without external supply of pressurized gas by in situ generation of H₂. Slightly elevated temperatures (45°) and low current densities (10 mA/cm²) are favorable conditions for this type of electrochemical nitrile hydrogenation. Our synthetic protocol does not require high‐pressure equipment or chemical hazards, is environmentally very friendly, and more economical than traditional methods. The concentration of adsorbed H^. radicals on the catalyst surface can be easily controlled by adjusting the electric potential, which may lead to improved product selectivity and, at the same time, reduces the risk of explosion and fire.     

Laboratory investigation of biodegradability of a polyurethane foam under anaerobic conditions

Polyurethane (PU) foams can be used in many remediation applications as an isolation material to prevent the release of hazardous materials into the environment. The integrity of a PU foam was investigated in this study using short-term accelerated laboratory experiments including bioavailability assays, soil burial experiments, and accelerated bioreactors to determine the fate of PU foam in the soil where anaerobic processes are dominant. The experimental results have shown that the studied PU foam is likely not biodegradable under anaerobic conditions. Neither weight loss nor a change in the tensile strength of the PU material after biological exposure was observed. The FT-IR chemical signature of the PU foams was also nearly identical before and after biological exposure. The composition of the PU material (aromatic polyester and polyether PU) used in this study could have played a significant role in its resistance to microbial attack during the short-term accelerated experiments.     

Synthesis and biological evaluation of 3-amino-propan-1-ol based poly(ether imine) dendrimers

A general synthetic strategy for the rapid construction of poly(ether imine) dendrons and dendrimers with a nitrogen core, originating from 3-amino-propan-1-ol, is described. A new trifunctional monomer, namely, 3-[bis-(3-hydroxypropyl)amino]propan-1-ol, was used in a divergent synthesis of dendrimers up to the third generation. This method permitted installation of, either alcohol, amine, nitrile, ester or carboxylic acid groups at the peripheries the dendrimers. Cytotoxicity studies on water-soluble carboxylic acid terminated dendrimers were conducted and these studies revealed that poly(ether imine) dendrimers were non-toxic. These results illustrate that poly(ether imine) dendrimers are useful for biological studies.     

Micellar effect of sodium dodecyl sulfate on the reactions between iron(II) and p-benzoquinone, and iron(III) and hydroquinone

The micellar effet of sodium dodecyl sulfate (SDS) on the initial stages of the reaction between (1) Fe(II) and p-benzoquinone, and (2) Fe(III) and hydroquinone have been investigated. In the former case acceleration was observed, the rate-[surfactant] profile showing a maximum. SDS has an inhibitory effect on the latter reaction. Kinetic analysis has been carried out using Berezin's approach.

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() 1) Fe(II) 2) Fe(III) . - . . , .

     

A family of oxorhenium(v) complexes incorporating chelated monoanionic ONN reduced Schiff base and dianionic ONNO tetradentate ligands: synthesis, spectroscopic and electrochemical studies

The green colored complexes of the type Re(V)O(L(SB))Cl(2), 1, have been synthesised by reacting NBu(4)[ReOCl(4)] with HL(SB) in dry ethanol. Here, L(SB)(-) are the deprotonated forms of N-(2-hydroxybenzyl)-2-picolylamine (HL(SB)(1)); N-(2-hydroxybenzyl)-N',N'-dimethylethylenediamine (HL(SB)(2)) and N-(2-hydroxybenzyl)-N',N'-diethylethylenediamine (HL(SB)(3)). Similarly, NBu(4)[ReOCl(4)] reacted with N,N-bis(2-hydroxybenzyl)-2-picolylamine (H(2)L(1)); N,N-bis(2-hydroxybenzyl)-N',N'-dimethylethylenediamine (H(2)L(2)); N,N-bis(2-hydroxybenzyl)-N',N'-diethylethylenediamine (H(2)L(3)); [N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)]-2-aminoethanol (H(2)L(4)); [N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)]-2-methyl-2-amino-1-propanol (H(2)L(5)); N,N-bis(1-hydroxyethyl)-2-picolylamine (H(2)L(6)), to give the monochloro complexes Re(V)O(L)Cl, 2. The X-ray structures of the complexes are reported. The molecular structures observed in the solid state are preserved in solution ((1)H NMR). In acetonitrile solution the Re(V)O(L)Cl, 2, display a one-electron couple, Re(VI)O(L)Cl(+)-Re(V)O(L)Cl, near 1.0 V vs SCE. The electrogenerated hexavalent complexes [Re(VI)O(L)Cl]ClO(4), 3, are paramagnetic and display sextet EPR spectra in solution at room temperature (A(av) approximately 417 (G), g approximately 1.914).     

X-band e.p.r. spectra of mixed-ligand copper(II) complexes

E.p.r. spectra of [Cu(et2dtc)2], Na[Cu(asp/glut)(et2dtc)] and Na2[Cu(asp/glut)(et2dtc)2] in the polycrystalline state have been recorded and discussed. The complexes display an antiferromagnetic exchange interaction, increasing in the order: Na2[Cu(asp/glut)(et2dtc)2] < Na[Cu(asp/glut)(et2dtc)] < [Cu(et2dtc)2] This revised version was published online in June 2006 with corrections to the Cover Date.     

Extractive spectrophotometric determination of molybdenum as a thiocyanate-2-acetylpyridinethiosemicarbazone complex

A new spectrophotometric method for the determination of molybdenum is based on the extraction of the orange red molybdenum thiocyanate-2-acetylpyridinethiosemicarbazone complex into chloroform from hydrochloric acid. The complex has an absorption maximum at 470 nm with a molar absorptivity of 1.7 × 10⁴ liters mol^?1 cm^?1. Beer's law is valid from 0.1 to 6.5 ppm of molybdenum. The equilibrium shift method indicated a 1:4:2 complex. The method has been used successfully for the determination of molybdenum in molybdenum steels.     

A Highly stereospecific and efficient synthesis of homopentafluoro- phenylalanine

A short and efficient synthesis of homopentafluorophenylalanine (6) from oxazolidine aldehyde 1 in 57% overall yield and in > 98% ee is described. The enantiomeric excess of the product was determined by 19F NMR analysis of the coupling product derived from 5 and L-Ser(O-t-Bu)-OCH3, by comparison to a dipeptide obtained from racemic 5.     

Structure of 4-[4-(Dimethylamino)-Phenylazo] Benzeneboronic Acid and Its Cyclic Esters with D-Glucose: A Computational Study

We present results from a computational study of 4-[4-(dimethylamino)-phenylazo] benzene boronic acid (DABBA) (the 4'-boronic acid isomer of the aminoazobenzene dye N,N-dimethylaminoazobenzene) and its associated anion, as well as, several cyclic esters formed from these azoborates and various conformers of D-glucose. Azo dyes that also contain one or more boronic acid functional groups are of practical importance in the development of chemical sensors for saccharide recognition because of their ability to induce a visible color change upon binding. The lowest-energy DABBA:D-glucose esters found in this investigation consistently involved at least one of the exocyclic hydroxymethyl groups on the D-glucose moiety rather than vicinal cis or trans diol arrangements of hydroxyl groups on the ring.