Ueber einige Derivate der drei isomeren Xylole

Radziszewski, Br.; Wispek, P.

doi:10.1002/cber.18820150266

Cited by 5 publications

(2 citation statements)

References 2 publications

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“…(14,235). Density: 1.3711 a t 23" (235). The rate of reaction with dimethylaniline at 40" is 8.625 X 10'; with triisoamylamine at 40°C.…”

Section: 5"c (211)mentioning

confidence: 99%

Lachrymators.

Jackson¹,

Jackson²

1935

Chem. Rev.

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Many chemical compounds possess more or less lachrymatory properties varying in intensity from mild irritation to severe, with a flow of tears so copious as to blind the victim temporarily. Some of these compounds, like chloropicrin, are also toxic. The lachrymatory property seems to be connected with the halogen group, and all lachrymators contain one of the halogens. In general, those compounds containing iodine have the strongest lachrymatory effect; bromine compounds are less powerful and chlorine compounds still less effective (304). The comparative rarity and expense of iodine makes the use of this element impractical. Most of the lachrymators used during the World War contained bromine and some, like bromobenzyl cyanide, were extremely effective. But bromine is quite expensive as compared with chlorine, and the development of the lachrymator chloroacetophenone, which is as effective as bromobenzyl cyanide, makes it appear probable that in the future no other lachrymatory gas will be manufactured. It is an interesting fact that even as early as 1887 Prof. Bayer, in his lectures to advanced students, included a reference to the military value of lachrymators (180). When tear gas is referred to by the general public, chloroacetophenone is usually meant.The chemical agents introduced during the World War proved very effective, as shown by the reports of the War Departments of the countries involved and the increased number of gas shells fired during the latter part of the war. Despite these facts, there is still an unholy fear of such agents on the part of the average citizen, owing to the mass of war propaganda against the use of gas and the lack of accurate information concerning same.Men fear the unknown; it is easier for them to maintain morale in the face of bullets, naked bayonets, and the sword's edge than in the presence of invisible gas; likewise a mob has less fear of the fire hose, night clubs, and bullets than of gas. There is always the uncertainty in their minds as to the effects of the gas, and more especially if there be a little smoke mixed with it, for they know not what may be behind it. The only real danger of serious injury from using non-toxic tear gas is from the possibility that members of the crowd may be trampled upon in attempts to escape. 195

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“…(14,235). Density: 1.3711 a t 23" (235). The rate of reaction with dimethylaniline at 40" is 8.625 X 10'; with triisoamylamine at 40°C.…”

Section: 5"c (211)mentioning

confidence: 99%

Lachrymators.

Jackson¹,

Jackson²

1935

Chem. Rev.

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“…The first approach involves the multicomponent reaction of 1,2dicarbonyl with aldehydes and a suitable nitrogen source (Scheme 1a, right). [15] The second approach involves the annulation of amidines with functionalized alkenes, simplifying the synthesis of 2,4,5substituted imidazoles (Scheme 1a, left). [16] To overcome the limitations of substrates, benzylamines and two molecules of nitriles are exploited, simplifying the synthesis of 2,4,5-substituted imidazoles.…”

Section: Introductionmentioning

confidence: 99%

Constructing 5‐Methyl‐2,4‐diaryl‐1H‐imidazoles Using Calcium Carbide as Alkyne Source via A3‐Coupling Cyclization

Sun

Zhang

2023

Adv Synth Catal

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Imidazole derivatives are critical building blocks in the synthesis of pharmaceuticals, fluorescent materials, and ligands. Despite the development of many strategies, the reliable synthesis of 2,4,5-substituted imidazoles remains heavily researched. In this study, we present a protocol for synthesizing 2,4,5-substituted imidazole-bearing methyl groups using A3-coupling cyclization with calcium carbide as the acetylene source, reacting with amidines and aldehydes. This methodology is characterized by several features, including the utilization of a solid alkyne source, readily accessible starting materials, and applicability to 34 examples.

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Azomethine, 1‐Azaallyl‐Anionen und metastabile sek. Enamine

et al. 1980

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Die E/Z-Gleichgewichtskonstanten der Keton-anile 6 a -s hangen nicht wesentlich vom induktiven Substituenteneffekt ab. Die fur eine Zuordnung geeigneten ' H-NMR-Verschiebungen gelten auch fur vergleichbare, meist isomerenfreie Azomethine 6 aa-pp und gehorchcn dem Anisotropiemodell. Durch Metallierung entstehen die 1-Azaallyl-Anionen 7; diese werden 'H-NMRspektroskopisch charakterisiert. Kinetische und thcrmodynamische Reaktionslenkung fuhren zu unterschiedlichen Vorzugskonfigurationen dieser Anionen; die Methanolyse liefert metastabile sek. Enamine 8 unter regio-und stereospezifischer N-Protonierung. Aus den €/Z-Gleichgewichtslagen lassen sich weitere Substituentenparameter id abschatzen. Azomethines, 1-Azaallyl Anions, and Metastable Secondary Enamines13*)E / Z equilibrium constants of the ketone anils 6 a -s d o not depend significantly on the inductive substituent effect. ' H NMR chemical shifts used for configurational classification are also effective for assignments in comparable, isomerically almost pure azomethines 6aa-pp and may be explained by the anisotropic shift model. The 1-azaallyl anions 7 prepared by deprotonation are characterized by 'H NMR spectroscopy. Kinetic and thermodynamic control of this metallation reaction result in different preferential configurations of such anions, the methanolysis of which yields metastable sec. enamines 8 by regio-and stereospecific N-protonation. It is possible to estimate further substituent parameters I d from E/Z equilibria. Die €/Z-Gleichgewichtskonstanten von Azomethinen lassen sich mit neuen Substituentenparametern berechnen, deren GroBe anscheinend vorwiegend sterisch bedingt ist*). In der vorliegenden Arbeit untersuchen wir, ob sich der induktive Substituenteneffekt auf die E/Z-Gleichgewichtslage auswirkt. Bei der Deprotonierung dcr Azomethine entstehen synthetisch wichtige 1 -Azaallyl-Anionen, deren Protonenspektren bisher kaurn untersucht wurden. Das in reiner E-Form vorliegende Pinakolon-anil wird auffallend langsani d e p r~t o n i e r t~.~) ; die durch C-Iminoalkylierung3) belegte Metallierung lie0 sich jedoch durch C-Deuterierung nicht sofort nachweisen4). Dies veranlante uns, spektroskopisch nach den Primarurodukten der Protolyse derartiger Anionen zu fahnden. A. SynthesenArylessigsauren 1 (R' = Aryl) stellten wir aus den Chlormethyl-Vorstufen oder aus Acetophenon-Derivaten5) her. Aus ihren Chloriden 2 gewinnt man die monosubstituierten 2-Propanone 3 am besten mit (Ethoxymagnesio)malonester6~7) (Vorschrift A im Exp. Teil). Die alternative Synthese von 3 nach Tiffeeneau*) durch nucleophile Substitution an Chloraceton gelingt

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Ueber einige Derivate der drei isomeren Xylole

Cited by 5 publications

References 2 publications

Lachrymators.

Lachrymators.

Constructing 5‐Methyl‐2,4‐diaryl‐1H‐imidazoles Using Calcium Carbide as Alkyne Source via A3‐Coupling Cyclization

Azomethine, 1‐Azaallyl‐Anionen und metastabile sek. Enamine

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