Oxidative cyclizations. VI. Mechanism of cyclization of N-chloro-2-nitroanilines to benzofuroxans under alkaline conditions

1984 ◽  
Vol 37 (2) ◽  
pp. 341 ◽  
Author(s):  
KJ Chapman ◽  
LK Dyall ◽  
LK Frith
Keyword(s):  
Nitro Group ◽  
Chloride Ion ◽  
Butyl Alcohol ◽  
Oxidative Cyclizations ◽  
Alkaline Conditions ◽  
Ccl4 Solution ◽  
Conjugate Base

An improved synthesis of N-chloro-2-nitroanilines used chlorine in CCl4 solution to halogenate the 2-nitroaniline. Treatment of these CCl4 solutions of the N-chloroamines with methanolic lithium methoxide, or potassium t-butoxide in t-butyl alcohol, produced a transient red colour, and quantitative yields of the corresponding benzofuroxan (benzofurazan 1-oxide) were obtained. U.v. and e.s.r. spectra indicated that the red species is the conjugate base of the N-chloroamine. On the basis of rate measurements, it is concluded that this red anion ejects chloride ion irreversibly to yield a singlet ortho-nitrophenylnitrene, which then rapidly cyclizes to the benzofuroxan. The ortho-nitro group does not assist in chloride ion ejection.

Octahedral cobalt(III) complexes of the chloropentammine type. XVIII. Hydrolysis of some Chloroanilinebis(ethylenediamine)cobalt(III) complexes, and a rationalization for the conjugate-base and ion-pair mechanisms

1969 ◽  
Vol 22 (9) ◽  
pp. 1851 ◽  
Author(s):  
SC Chan ◽  
OW Lau
Keyword(s):  
Chloride Ion ◽  
Ion Pair ◽  
Base Hydrolysis ◽  
Methyl Substituent ◽  
Substituted Anilines ◽  
First Order ◽  
Base Mechanism ◽  
Higher Temperature ◽  
Hydrolysis Of ◽  
Conjugate Base

The kinetics for the appearance of chloride ion from aqueous solutions of the cis-chloroanilinebis(ethylenediamine)cobalt(III) cation are determined over the pH ranges of 2-3 at 40.0� and of 8-9 at 0�. By using self-buffered mixtures, the rate constants for the reaction are also measured at 40.0� as a function of the concentration of complex or of free aniline. The results are discussed in terms of the conjugate- base mechanism. A rationalization of this mechanism and the ion-pair mechanism is proposed to incorporate the base hydrolysis of other previously investigated systems where the complexes are decidedly much less acidic. At a higher temperature (65.0�), both chloride ion and aniline are liberated at similar rates, and the process is treated as parallel first-order reactions. By using complexes with meta- and para-substituted anilines, the effect of the methyl substituent on reactivity is studied.

scholarly journals Biodegradation of waste greases and biochemical properties of a novel lipase from Pseudomonas synxantha PS1

2016 ◽  
Vol 62 (7) ◽  
pp. 588-599 ◽  
Author(s):  
Xianghai Cai ◽  
Siqi Chen ◽  
Hong Yang ◽  
Wei Wang ◽  
Lin Lin ◽  
...  
Keyword(s):  
Lipase Activity ◽  
Produced Water ◽  
Wild Strain ◽  
Biochemical Properties ◽  
Butyl Alcohol ◽  
Oil Well ◽  
Lipase Gene ◽  
Reading Frame ◽  
16S Rdna Sequence Analysis ◽  
Alkaline Conditions

A lipase-producing bacterial strain was isolated from oil-well-produced water in Shengli oilfield (Shandong province, China) and was identified as Pseudomonas synxantha by 16S rDNA sequence analysis (named Pseudomonas synxantha PS1). Strain PS1 showed a maximum lipase activity of 10.8 U/mL after culturing for 48 h at 30 °C, with lactose (4 g/L) as carbon source, tryptone (8 g/L) as nitrogen source, olive oil (0.5%, v/v) as inductor, and the initial pH 8.0. Meanwhile, the lipase gene from P. synxantha PS1 was cloned and expressed in Escherichia coli BL21 with the vector pET28a. The novel gene (lipPS1) has an open reading frame of 1425 bp and encodes a 474 aa lipase (LipPS1) sharing the most identity (87%) with the lipase in Pseudomonas fluorescens. LipPS1 preferably acted on substrates with a long chain (C10–C18) of fatty acids. The optimum pH and temperature of the recombinant enzyme were 8.0 and 40 °C, respectively, towards the optimum substrate p-nitrophenyl palmitate. The LipPS1 showed remarkable stability under alkaline conditions and was stable at pH 7.0–10.0 (retaining more than 60% activity). From the organic solvents tests, the lipase was activated by 15% (v/v) methanol (112%), 15% ethanol (127%), and 15% n-butyl alcohol (116%). LipPS1 presented strong biodegradability of waste grease; 93% of waste grease was hydrolyzed into fatty acid after 12 h at 30 °C. This is the first report of the lipase activity and lipase gene obtained from P. synxantha (including wild strain and recombinant strain) and of the recombinant LipPS1 with the detailed enzymatic properties. Also a preliminary study of the biodegradability of waste greases shows the potential value in industry applications.

Assembly of the 1-Azaspiro[5.5]undecane Framework Associated with Perhydrohistrionicotoxin via Electrocyclic Ring-Opening of a Ring-Fused gem-Dichlorocyclopropane and Trapping of the Resulting π-Allyl Cation by a Tethered, Nitrogen-Centered Nucleophile

2006 ◽  
Vol 59 (7) ◽  
pp. 415 ◽  
Author(s):  
Martin G. Banwell ◽  
Florian Vogt ◽  
Angela W. Wu
Keyword(s):  
Ring Opening ◽  
Chloride Ion ◽  
Sequential Treatment ◽  
Silver Acetate ◽  
Reaction Conditions ◽  
Rigid System ◽  
Allyl Cation ◽  
Type 3 ◽  
Unsaturated Nitrile ◽  
Conjugate Base

The carbamate-tethered gem-dichlorocyclopropane 27 was prepared, as a mixture of epimers, in ten steps from commercially available β,γ-unsaturated nitrile 9. Upon treatment with silver acetate under a range of reaction conditions, compound 27 underwent electrocyclic ring opening to give the corresponding π-allyl cation that was then trapped by the reaction solvent, chloride ion, and/or acetate ion, and so affording varying mixtures of the chlorocyclohexenes 28, 29, 30, and/or 31. Sequential treatment of the same substrate with LiHMDS (to generate the conjugate base of this carbamate) then silver tetrafluoroborate afforded the chlorocyclohexadiene 32 as the exclusive product of reaction. No spirocyclization product of the type 3 arising from trapping of the intermediate π-allyl cation by the tethered carbamate was observed under any of the reaction conditions examined. In contrast, analogous treatment of the more rigid system 38 afforded compound 39 incorporating the 1-azaspiro[5.5]undecane framework associated with the potent neurotoxin perhydrohistrionicotoxin (2).

A crystalline–amorphous Ni–Ni(OH)2 core–shell catalyst for the alkaline hydrogen evolution reaction

2020 ◽  
Vol 8 (44) ◽  
pp. 23323-23329
Author(s):  
Jing Hu ◽  
Siwei Li ◽  
Yuzhi Li ◽  
Jing Wang ◽  
Yunchen Du ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Core Shell ◽  
Alkaline Conditions

Crystalline–amorphous Ni–Ni(OH)2 core–shell assembled nanosheets exhibit outstanding electrocatalytic activity and stability for hydrogen evolution under alkaline conditions.

Germination of leucaena and Rhodes grass seeds in saline and alkaline conditions

2016 ◽  
Vol 44 (3) ◽  
pp. 461-474 ◽  
Author(s):  
J.B. Wehr ◽  
P.M. Kopittke ◽  
S.A. Dalzell ◽  
N.W. Menzies
Keyword(s):  
Rhodes Grass ◽  
Alkaline Conditions

PHENOLIC METABOLITES OF DL-NORGESTREL: A METHOD FOR THE REMOVAL OF 1-HYDROXYLATED METABOLITES, POTENTIAL SOURCES OF PHENOLIC ARTIFACTS

1974 ◽  
Vol 76 (4) ◽  
pp. 789-800 ◽  
Author(s):  
Samuel F. Sisenwine ◽  
Ann L. Liu ◽  
Hazel B. Kimmel ◽  
Hans W. Ruelius
Keyword(s):  
Urinary Metabolites ◽  
Ion Exchange Resin ◽  
Gas Chromatography Mass Spectrometry ◽  
Phenolic Metabolites ◽  
Hydroxylated Metabolites ◽  
Analytical Work ◽  
Potential Sources ◽  
Alkaline Conditions ◽  
Artifact Formation ◽  
Work Up

ABSTRACT The identification of 1β-hydroxynorgestrel among the urinary metabolites of dl-norgestrel and the facile transformation of this compound under mild alkaline conditions to a potentially oestrogenic phenol provide an experimental basis for the conclusion advanced by others that the oestrogens present in the urine of subjects treated with synthetic progestens are artifacts formed during analytical work-up. A method has been devised which eliminates 1-hydroxylated metabolites as potential sources of phenolic artifacts. This method is based on the reduction by NaBH4 of the 1-hydroxy-4-en-3-one grouping in the A ring thereby excluding the possibility of aromatization during later fractionation on a basic ion exchange resin that separates neutral from phenolic metabolites. In the urines of women treated with 14C-dl-nogestrel, only 0.17–0.27% of the dose is found to have phenolic properties when this method is used. Two of the phenolic metabolites, 18-homoethynyloestradiol and 16β-hydroxy-18-homoethynyloestradiol, are present in amounts smaller than 0.01 % of the dose. Without the reduction steps the percentages are noticeably higher, indicating artifact formation under alkaline conditions. Similar results were obtained with urines from African Green Monkeys (Cercopithecus Aethiops) that had been dosed with 14C-dl-norgestrel. Radiolabelled 18-homoethynyloestradiol and 16β-hydroxy-18-homoethynyloestradiol were isolated from monkey urine and their identity confirmed by gas chromatography-mass spectrometry.

NAS 825

Alloy Digest ◽  
2012 ◽  
Vol 61 (2) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Stress Corrosion ◽  
Tensile Properties ◽  
Nickel Alloy ◽  
Stress Corrosion Cracking ◽  
Chloride Ion ◽  
Heat Treating ◽  
Corrosion Cracking ◽  
Corrosion Resistant

Abstract NAS 825 is a corrosion-resistant nickel alloy that has resistance to both oxidizing and reducing environments, and with 42% nickel, the alloy is very resistant to chloride-ion stress-corrosion cracking. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-694. Producer or source: Nippon Yakin Kogyo Company Ltd.

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