Oxidation of sulfides to sulfoxides. Part 1: Oxidation using halogen derivatives

The complete primary and three-dimensional solution structures of subtilosin A (1), a bacteriocin from Bacillus subtilis, were determined by multidimensional NMR studies on peptide produced using isotopically labeled [13C,15N]medium derived from Anabaena sp. grown on sodium [13C]bicarbonate and [15N]nitrate. Additional samples of 1 were also generated by separate incorporations of [U-13C,15N]-l-phenylalanine and [U-13C,15N]-l-threonine using otherwise unlabeled media. The results demonstrate that in addition to having a cyclized peptide backbone (amide between N and C termini), three cross-links are formed between the sulfurs of Cys13, Cys7, and Cys4 and the α-positions of Phe22, Thr28, and Phe31, respectively. The stereochemistry of all residues in 1 except for the three modified ones was confirmed to be l by complete desulfurization with nickel boride, acid hydrolysis to the constituent amino acids, and conversion of these to the corresponding pentafluoropropanamide isopropyl esters for chiral GC MS ana...

Structure of Subtilosin A, a Cyclic Antimicrobial Peptide from Bacillus subtilis with Unusual Sulfur to α-Carbon Cross-Links: Formation and Reduction of α-Thio-α-Amino Acid Derivatives†,‡

Halogenated disinfection byproducts (DBPs) are generated via reactions with natural organic matter (NOM) in chlorine disinfection of drinking water. How large NOM molecules are converted to halogenated aliphatic DBPs during chlorination remains a fascinating yet largely unresolved issue. Recently, many relatively toxic halogenated aromatic DBPs have been identified in chlorinated drinking waters, and they behave as intermediate DBPs to decompose to halogenated aliphatic DBPs. There is still one gap between NOM and halogenated aromatic DBPs. In this study, nine nonhalogenated aromatic compounds were identified as new intermediate DBPs in chlorination, including 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, 3-formyl-4-hydroxybenzoic acid, salicylic acid, 5-formyl-2-hydroxybenzoic acid, 4-hydroxyphthalic acid, 4'-hydroxyacetophenone, 4-methylbenzoic acid, and 4-hydroxy-3-methylbenzaldehyde. These nonhalogenated aromatic DBPs formed quickly and reached the maximum levels at relatively low chlorine doses within a short contact time, and their formation pathways were proposed. The formation kinetics of three nonhalogenated aromatic DBPs and their corresponding monochloro-/dichloro-substitutes during chlorination were then modeled. The nonhalogenated aromatic DBPs contributed up to 84% of the formed monochloro-substitutes and 22% of the formed dichloro-substitutes, demonstrating that they somewhat acted as intermediates between NOM and halogenated aromatic DBPs. Furthermore, the formed nonhalogenated aromatic DBPs were found to be removed by >50% by granular activated carbon adsorption.

Nonhalogenated Aromatic DBPs in Drinking Water Chlorination: A Gap between NOM and Halogenated Aromatic DBPs.

CuFe, CuCo and CuNi nanoparticles as catalysts for higher alcohol synthesis from syngas: a comparative study

The MAB phases are atomically layered, ternary or quaternary transition metal (M) borides (TMBs), with the general formula (MB)2zAx(MB2)y (z = 1–2; x = 1–2; y = 0–2), whose structures are composed ...

A progress report on the MAB phases: atomically laminated, ternary transition metal borides

Rapid oxidation of sulfides and sulfoxides with sodium hypochlorite

Synthetically useful reactions with nickel boride. a review

Oxidative cleavage of 1,2-diols, α-ketols and 1,2-diketones with aqueous sodium hypochlorite

A simple and rapid procedure for the pinacolization of aromatic aldehydes and reduction of hindered ketones with inexpensive aluminium and KOH in methanol at ambient temperature is reported. The pinacolization and reduction are proposed to be proceeding via single electron transfer from aluminium.

Pinacolization and reduction of aromatic carbonyls with aluminium–KOH

(1996). RAPID OXIDATION OF SULFIDES AND SULFOXIDES WITH SODIUM HYPOCHLORITE. Organic Preparations and Procedures International: Vol. 28, No. 2, pp. 234-237.

A. Gogia

Papers

Rapid oxidation of sulfides and sulfoxides with sodium hypochlorite

Synthetically useful reactions with nickel boride. a review

Oxidative cleavage of 1,2-diols, α-ketols and 1,2-diketones with aqueous sodium hypochlorite

Pinacolization and reduction of aromatic carbonyls with aluminium–KOH

Rapid Oxidation of Sulfides and Sulfoxides with Sodium Hypochlorite