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In this paper, we present the synthesis of new selenoloquinoxaline derivatives starting from 2‐chloroquinoxaline‐3‐carbonitrile 1. The compound 1 was subjected to a reaction with selenium metal in the presence of NaBH4 as a reducing agent in ethanol, under a nitrogen atmosphere. This reaction resulted in the formation of the sodium salt of 3‐cyanoquinoxaline‐2‐selenolate, which was subsequently reacted with α‐halogenated carbonyl compounds in situ. This reaction produced a series of newly synthesized 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐substituents. Ethyl 3‐aminoselenolo[2,3‐b]quinoxaline‐2‐carboxylate 3a was hydrolyzed by sodium hydroxide to give the corresponding sodium salt 9. This salt was then refluxed with acetic anhydride to produce oxazinone compound 10. The reaction of compound 10 with ammonium acetate afforded pyrimidoselenolo[2,3‐b]quinoxaline derivative 11. Compound 11 was then chlorinated using phosphorous oxychloride to give the corresponding chlorocompound. [ABSTRACT FROM AUTHOR]

The paper by Gershoni-Poranne and Chen (R. Gershoni-Poranne, P. Chen, Chem. Eur. J. 2017, 23, 4659) gives an incorrect definition of covalent bonding. Furthermore, the assignment of so-called charge shift bonds in ammonium compounds has no physical foundation and is conceptually redundant. [ABSTRACT FROM AUTHOR]

A response to the comment by Gernot Frenking, outlining common ground, as well as differences, with regard to a recent paper on charge-shift bonding in quaternary ammonium cations. [ABSTRACT FROM AUTHOR]

Berberine and berberine chloride as quaternary ammonium salts belong to the rare 'basic natural dyes'. Berberine is e.g. found in the bark of common barberry. It is a yellow natural dye, which dyers appreciate. It is possible to dye wool or leather even without a mordant. Biosynthesis and total synthesis of berberine are described. As an alkaloid, it shows a variety of physiological effects. Formerly used in traditional medicine it is now under intensive pharmacological investigation. We describe the isolation of berberine chloride from barberry bark without chromatography, present its spectra and their interpretations. Besides, barberry fruits are a piquant delicacy of Persian cuisine. A recipe for dyeing and another one for the kitchen round this paper off. Based on a Bachelor thesis this project is a follow up of the recent book 'Classics in Spectroscopy' by S. Berger und D. Sicker (Wiley-VCH 2009). [ABSTRACT FROM AUTHOR]

A novel and efficient approach to sulfonamides has been developed. Using TBHP as the oxidant and NH4I (20 mol%) as the catalyst, arylsulfonyl hydrazides reacted with amines to provide sulfonamides in moderate to good yields. Possible reaction pathway for the formation of the products was also discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper describes a new analytical method, using a combination of ammonium pyrrolidine dithiocarbamate/methyl isobutyl ketone (APDC-MIBK) microextraction and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), for the determination of the concentrations of Cd and Pb in aqueous samples. Only 200 μL of organic solvent was used throughout the entire analysis process, with enhancement factors as high as 25. Recoveries from replicate analyses of natural water [NIST 1640(a)] containing mean concentrations of 3.1 μg Cd L−1 and 9.3 μg Pb L−1 were 95 ± 3 and 104 ± 4%, respectively. The corresponding detection limits were 0.6 μg L −1 for Cd and 0.9 μg L −1 for Pb. The main advantage of this approach is its simplicity in terms of sample preparation, as demonstrated by quantifying the levels of Cd and Pd in real samples, including tap water, groundwater, and seawater, using a standard addition method. [ABSTRACT FROM AUTHOR]

A detailed molecular understanding of the mechanisms of the dephosphorylation of phosphate triesters due to nucleophilic attack can be very useful for the design of nucleophiles that are more efficient. In this work, we report a combined experimental and theoretical study of the reaction of hydroxylamine with paraoxon. The profile of the reaction rate according to pH was determined, and it was found that protonated hydroxylamine was unreactive, while the neutral form reacted via the zwitterion tautomer, with an overall free energy barrier of 23.0 kcal mol‐1. The anionic form was the most reactive, with a free energy barrier of 18.1 kcal mol‐1. Computational calculations revealed 2 mechanisms for the nucleophilic attack of the zwitterion form: the usual backside attack and a new frontside attack mechanism. The former proceeded according to a 2‐step associative mechanism, while the latter was a concerted single‐step mechanism involving attack of the hydroxylamine oxygen on the phosphorus center and interaction of the NH3+ group with the oxygen of the P═O group. The calculations indicated that the free energy barrier for the frontside attack was more favorable than the backside attack by 3 kcal mol‐1, supporting the notion that the observed reaction occurs by frontside attack. The reaction with the anionic hydroxylamine form occurred according to a single‐step concerted ANDN mechanism. This paper presents a one‐step front side ANDN low‐barrier energy profile alternative route to the classic backside mechanism AN + DN for the dephosphorylation of paraoxon by hydroxylamine applying computational methods supported by experimental evidences. [ABSTRACT FROM AUTHOR]