Die quantitative Bestimmung von 2,4-Dinitro-o-kresol, 2,4-Dinitro-o-sek.-butylphenol und 2,4-Dinitro-o-isopropylphenol

Zusammenfassung Es wird eine colorimetrische Methode zur Bestimmung der in Pflanzenschutz wichtigen Wirkstoffe Dinitro-o-kresol, 2,4-Dinitro-o-sek.-butylphenol und 2,4-Dinitro-o-isopropylphenol in technischen Produkten und Pflanzenschutzmitteln beschrieben, in der die Reaktion von Bose, Entstehung einer rotgelben FÄrbung durch Alkohol und Alkali bei Gegenwart von Glucose benutzt wird. Der mittlere Fehler liegt bei etwa ± 1,5% bei Gegenwart von Teerölen (Obstbaumkarbolineum) bei ±2–3%.     

Nachweis von Phenylhydrazin,p-Nitro-phenylhydrazin und 2,4-Dinitrophenylhydrazin neben Hydrazin,Hydroxylamin, Anilin,p-Nitranilin und 2,4-Dinitro-anilin

Zusammenfassung Nitro-phenylhydrazinderivate kann man auf der Basis ihrer Indikator-wirkung unterscheiden. p-Nitrophenylhydrazin entfärbt sich in saurem Medium, 2,4-Dinitro-phenylhydrazin wird in alkalischem Medium dunkelbraun. Außerdem liefern beide Verbindungen bei Oxydation mit Kaliumbromat ein Diazoniumsalz, das man in alkoholischer Lösung mit-Naphthol kuppelt. Nach Zusatz von Alkalien erhält man daraus bei p-Nitrophenylhydrazin eine violette, bei 2,4-Dinitro-phenylhydrazin eine blaue Farbe.

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Summary Nitrophenylhydrazine derivatives can be differentiated on the basis of their indicator action,p-Nitrophenylhydrazine is decolorized in acid surroundings, 2,4-dinitrophenylhydrazine turns brown in an alkaline medium. Furthermore, both compounds on oxidation with potassium bromate yield a diazonium salt that is coupled in alcoholic solution with-naphthol. Addition of alkali to thep-nitrophenylhydrazine product gives a violet color, whereas the corresponding 2,4-dinitrophenylhydrazine derivative is blue.

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Résumé On peut différencier les dérivés de la nitrophénylhydrazine d'après leur propriété d'indicateur. Lap-nitrophénylhydrazine se décolore en milieu acide, la dinitro-2,4 phénylhydrazine est brun-foncé en milieu alcalin. De plus, les deux composés conduisent par oxydation par le bromate de potassium à un sel de diazonium que l'on copule en solution alcoolique avec le-naphtol. Après addition d'une base, on obtient à partir de là, une coloration violette dans le cas de lap-nitrophénylhydrazine et bleue dans celui de la dinitro-2,4 phénylhydrazine.

     

Phenylhydrazin, p-Nitro-phenylhydrazin und 2,4-Dinitrophenylhydrazin

Ohne Zusammenfassung     

The preferred conformations of 2,4-dichlorophenol, 2,4-dichloroanisole and their sulphur analogues

Analysis of the benzene dipole moments of 2-chloroanisole and 2,4-dichloroanisole, 2-chlorothioanisole and 2,4-dichlorothioanisole shows these compounds to exist as trans. 2-Chlorophenol and 2,4-dichlorophenol, and their sulphur analogues, are mixtures of Cis and trans conformers. The populations of the cis conformers are, at 25°C, 86 and 78% for the phenols, and ca. 70 and 50% for the corresponding thiophenols. The influence of various factors, such as the non-additivity of the (2-ClC₆H₄X)-group moment and torsional oscillation of the H-X bond (especially the H-S bond), on the calculated populations has been discussed. Incidentally it has been shown that p-dimethoxybenzene and p-di-(methylthio)benzene, as well as p-phenylenediamine and p-diformylbenzene, are equimolecular mixtures of cis and trans conformers.     

Synthese,Struktur und Reaktivität eines 2,4-Diphosphino-1,3-diphospha-2,4-disilacyclobutans

Synthesis, Structure, and Reactivity of a 1,3-Diphosphino-2,4-diphospha-1,3-disilacyclobutane Pentamethylcyclopentadienyltrichlorosilane reacts with Li[Al(PH₂)₄] to give the stable 1,3-diphosphino-2,4-diphospha-1,3-disilacyclobutane 4 . Treatment of 4 with Lithium alkyls affords the Lithium phosphide 5 via regiospecific metalation of a ring phosphorus atom, and reaction with t-Bu₂Hg proceeds via oxidative P? P bond formation to yield the 1,4-disila-2,3,5,6-tetraphospha-bicyclo[2,1,1]-hexane 6 . Cleavage of pentamethylcyclopentadiene is observed during thermolysis of 4 at 200°C. 4–6 were characterised by NMR-spectroscopy, and 4 by an additional crystal structure determination.     

Reaction of 2,4-Diaryl-1,3-dithia-2,4-diphosphetane-2,4-disulfides with resorcinol

Russian Journal of General Chemistry -     

Crystal structures of 2,4-dimethylthioxanthene 10,10-dioxide, 2,4,9-trimethylthioxanthene 10,10-dioxide,and 2,4-dimethyl-9-isopropylthioxanthene 10,10-dioxide

The structures of 2,4-dimethylthioxanthene 10,10-dioxide, 1 , 2,4,9-trimethylthioxanthene 10,10-dioxide, 2 , and 2,4-dimethyl-9-isopropylthioxanthene 10,10-dioxide, 3 , have been determined by x-ray diffraction. The central ring of the thioxanthene ring system is in a boat conformation. The 9-methyl substituent in 2 and the 9-isopropyl substituent in 3 are both in the boat-axial conformation with respect to the central ring. The folding angles between the planes of the two benzo rings are 136.6°, 142.9°, and 134.3° for 1, 2 , and 3 , respectively.     

Kinetics and mechanism of the aminolysis of methyl 4-nitrophenyl,methyl 2,4-dinitrophenyl,and phenyl 2,4-dinitrophenyl carbonates

The reactions of methyl 4-nitrophenyl carbonate (MNPC) with a series of secondary alicyclic amines (SAA) and quinuclidines (QUIN), methyl 2,4-dinitrophenyl carbonate (MDNPC) with QUIN and 1-(2-hydroxyethyl)piperazinium ion (HPA), and phenyl 2,4-dinitrophenyl carbonate (PDNPC) with SAA are subjected to a kinetic investigation in aqueous solution, at 25.0 degrees C and an ionic strength of 0.2 M. By following spectrophotometrically the nucleofuge release (330-400 nm) under amine excess, pseudo-first-order rate coefficients (k(obsd)) are obtained. Plots of k(obsd) vs [amine] at constant pH are linear, with the slope (k(N)) being pH independent. The Br?nsted-type plot (log k(N) vs amine pK(a)) for the reactions of SAA with MNPC is biphasic with slopes beta(1) = 0.3 (high pK(a) region) and beta(2) = 1.0 (low pK(a) region) and a curvature center at pK(a)(0) = 9.3. This plot is consistent with a stepwise mechanism through a zwitterionic tetrahedral intermediate (T(+/-)) and a change in the rate-determining step with SAA basicity. The Br?nsted plot for the quinuclidinolysis of MNPC is linear with slope beta(N) = 0.86, in line with a stepwise process where breakdown of T(+/-) to products is rate limiting. A previous work on the reactions of SAA with MDNPC was revised by including the reaction of HPA. The Br?nsted plots for the reactions of QUIN and SAA with MDNPC and SAA with PDNPC are linear with slopes beta = 0.51, 0.48, and 0.39, respectively, consistent with concerted mechanisms. Since quinuclidines are better leaving groups from T(+/-) than isobasic SAA, yielding a less stable T(+/-), it seems doubtful that the quinuclidinolysis of PDNPC is stepwise, as reported.     

Anionic Polymerization of Z,Z-2,4Hexadienedinitrile

Abstract

Z,Z-2,4-Hexadienedinitrile, synthesized by the oxidative cleavage of o-phenylenediamine, was found to undergo anionic polymerization with n-BuLi in DMF at room temperature or below. The polymerization behavior appears to be similar to that of acrylonitrile polymerization using n-BuLi as initiator. Infrared and NMR analysis of the polymer indicate the presence of both 1,4 and 1,2 linkages, with the latter predominating.     

New organic nitrates. I. Synthesis of 1,3-benzoxazine-2,4-dione, 1,3-benzoxazine-2-thion-4-one, 1,3-benzothiazine-2,4-dione and quinazoline-2,4-dione derivatives

The preparation and the physico-chemical characterization of new heterocyclic organic nitrates containing 1,3-benzoxazine-2,4-dione, 1,3-benzoxazine-2-thion-4-one, 1,3-benzothiazine-2,4-dione and quinazo-line-2,4-dione moieties, are reported.     

2,4-Diaminodihydropyridine

Aminolysis of 4-alkylamino- and 4-dialkylamino-2-methylthiodihydropyridines (· HI)1, 2 resp.. under various reaction-condition leads to assymmetrically or symmetrically substituted 2,4-bisalkylamino- or 2,4-bisdialkylamino-and 2-alkylamino-4-dialkylamino- or 2-dialkylamino-4-alkylaminodihydro-pyridines3, 4, 5, 6 resp. On treatment with alkali only the aminogroup in pos. 4 of the pyridines3, 4, 5, 6 is hydrolyzed and 4-hydroxy-2-aminopyridines9 are formed. Different substituted 2,4-diaminodihydropyridines3, 4, 5, 6 can also be synthesized by reaction of 4-hydroxy-2-aminopyridines (·HCl)9 with amines. Also the aminolysis of 4-alkylamino-annd 4-dialkylaminodihydropyridinthiones7, 8 resp. is described.

     

Papierchromatographie der 2,4-Dinitrophenylhydrazone der Alk-2,4-dienale

Ohne Zusammenfassung