Dichloro structure

The acid aquation of four complexes of the type (Cr(NH3)a (OH2)4-xCl2]+, all of which contain rra/zj-dichloro configurations, have been investigated together with the rates of isomerization to a cw-dichloro structure with an unchanged ammine configuration. The aquation reactions were followed using a chloride ion specific electrode, and the results are collected in Table 13. 

In a search for fluorocarbons having anesthetic properties 1 2 dichloro 1 1 difluoropropane was subjected to photochemical chlorination Two isomeric products were obtained one of which was identified as 1 2 3 tnchloro 1 1 difluoropropane What is the structure of the second com pound" ... 

Structures A and A are nonsuperimposable mirror images of each other Thus although as 1 2 dichloro cyclohexane is chiral it is optically inactive when chair-chair interconversion occurs Such interconver Sion IS rapid at room temperature and converts opti cally active A to a racemic mixture of A and A Because A and A are enantiomers interconvertible by a conformational change they are sometimes re ferred to as conformational enantiomers... 

Pyridazinones may undergo ring contraction to pyrroles, pyrazoles and indoles, the process being induced either by an acid or base. The structure of the final product is strongly dependent on the reaction conditions. For example, 4,5-dichloro-l-phenylpyridazin-6(lFT)-one rearranges thermally to 4-chloro-l-phenylpyrazole-5-carboxylic acid (12S), while in aqueous base the corresponding 4-hydroxy acid (126) is formed (Scheme 40). 

In the case of phenazine, substitution in the hetero ring is clearly not possible without complete disruption of the aromatic character of the molecule. Like pyrazine and quinoxa-line, phenazine is very resistant towards the usual electrophilic reagents employed in aromatic substitution reactions and substituted phenazines are generally prepared by a modification of one of the synthetic routes employed in their construction from monocyclic precursors. However, a limited range of substitution reactions has been reported. Thus, phenazine has been chlorinated in acid solution with molecular chlorine to yield the 1-chloro, 1,4-dichloro, 1,4,6-trichloro and 1,4,6,9-tetrachloro derivatives, whose gross structures have been proven by independent synthesis (53G327). 

Pteridine, 4,7-dichloro-2-methylthio-synthesis, 3, 296 Pteridine, 3,4-dihydro-structure, 3, 279 Pteridine, 5,6-dihydro-properties, 3, 306 Pteridine, 5,8-dihydro-structure, 3, 306 Pteridine, 7,8-dihydro-... 

Pteridine-6,7-dione, 4-amino-2-chloro-chlorination, 3, 296 Pteridine-6,7-dione, 2,4-dichloro-synthesis, 3, 291 Pteridine-6,7-dione, 5-hydroxy-synthesis, 3, 316 Pteridine-6,7-dione, 8-methyl-reduction, 3, 298 Pteridine-2,6-diones structure, 3, 272 Pteridine-4,6-diones structure, 3, 272 synthesis, 3, 310 Pteridine-6,7-diones reduction, 3, 298 synthesis, 3, 316... 

H,6H-Pyridazino[4,5-d]pyridazine-l,5-dione, 4,8-dichloro-2,6-dimethyl-X-ray crystal structure, 3, 333 Pyridazino[l, 2-a]pyridazine-1,4-diones IR spectra, 3, 332... 

Thieno[3,4-d][l,3]dithiol-2-one, 1-nitro-synthesis, 6, 1013 Thieno[3,4-c]furan, 4,6-dichloro-synthesis, 6, 1013 Thieno[3,4-c]furan, tetraphenyl-formation, 4, 1060 synthesis, 4, 1060 UV spectra, 4, 1044 Thieno[3,2-6]furans structure, 4, 1039 synthesis, 6, 1020 Thieno[3,4-c]furans... 

In this solvent the reaction is catalyzed by small amounts of trimethyl-amine and especially pyridine (cf. 9). The same effect occurs in the reaction of iV -methylaniline with 2-iV -methylanilino-4,6-dichloro-s-triazine. In benzene solution, the amine hydrochloride is so insoluble that the reaction could be followed by recovery. of the salt. However, this precluded study mider Bitter and Zollinger s conditions of catalysis by strong mineral acids in the sense of Banks (acid-base pre-equilibrium in solution). Instead, a new catalytic effect was revealed when the influence of organic acids was tested. This was assumed to depend on the bifunctional character of these catalysts, which act as both a proton donor and an acceptor in the transition state. In striking agreement with this conclusion, a-pyridone is very reactive and o-nitrophenol is not. Furthermore, since neither y-pyridone nor -nitrophenol are active, the structure of the catalyst must meet the conformational requirements for a cyclic transition state. Probably a concerted process involving structure 10 in the rate-determining step... 

Factor b above is discussed in Sections II, B, 1 II, B, 4 and II, C. A hydrogen-bonded structure such as 221 can account for the facile reaction of 5-bromouracil or for the unique, so-called hydrolyzability of carboxymethylthio-azines (237). The latter may also react via the intramolecular mechanism indicated in 136. The hydrogen-bonded transition state 238 seems a reasonable explanation of the fact that 3,4,6- and 3,4,5-trichloropyridazines react with glacial acetic acid selectively to give 3-pyridazinones while other nucleophiles (alkoxides, hydrazine, ammonia, or sulfanilamide anion) react at the 4- and 5-positions. In this connection, 4-amino-3,5-dichloro-pyridazine in liquid hydrazine gives (95°, 3hr, 60%yield)the isomer-... 

Sodium methyl mercaptide in xylene was reported to react (25°, 2 hr) in a stepwise fashion with 3,5-dichloro-as-triazine to yield the 3-methylthio-5-chloro and then (70°, 2 hr) the 3,5-bis-methylthio derivatives. However, the structure of the former is very likely to be 307. With dimethylamine in benzene (25°, 5 min), ethyleneimine in ether (25°, 3 min), and alcoholic ammonia (25°, few min), this dichloro derivative was assumed to form 3-amino derivatives. The high reactivity of as-triazines is demonstrated by the facile ethoxylation... 

X-Ray crystal structure determinations of l-(aminocarbonyl)-3-methyl-4-methoxy-l//-pyrazol-5(2H)-one 107 (R = H) and l-(phenylaminocar-bonyl)-3-methyl-4-methoxy-l//-pyrazol-5(2H)-one 107 (R = Ph) demonstrated that both molecules exist in the crystal exclusively as NH-CO tautomers (97T5617). The tautomeric form similar to 104b is realized in the crystal of 4,4-dichloro-substituted pyrazolone 108 (93BSB735). 

Therapeutic Function Antibacterial Chemical Name 5,7-Dichloro-2-methvl-8-quinolinol Common Name Hydroxydichloroquinaldine, chloroquinaldol Structural Formula ci... 

Chemical Name 2,2-dichloro-1,1-difluoro-1-methoxyethane Common Name 1,1-difluoro-2,2-dichloroethyl methyl ether Structural Formula GHjOCF CHCI ... 

Chemical Name 2-((2,6-Dichloro-3-methylphenyl)emino] benzoic acid ethoxymethyl ester Common Name Etoclofene Structural Formula ... 

A stable perfluorinated 1,4-dithiocin 6 with a tetracyclic structure has been obtained in low yield by the reaction of l,2-dichloro-3.3,4,4-tctrafluorocyclobutene (5) with butyllithium and sulfur dichloride.4... 

Tricyclic 84 was prepared [91JCS(P1)1762] by the thermal intramolecular rearrangement of dichloro(pyrrolidinylcycloheptenyl)triazine 83. Its structure was confirmed by X-ray crystallography (Scheme 21). 

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