Dioxan 2,5-dichloro

Dichloro-l,4-dioxane, trans- 1,4-Dioxane, 2,3-dichloro-, trans- (3883-43-0), 65, 68... 

Structure. Copolymers BG, SG, SL, BCK and SCK exidbit liquid crystalline structures in the dry state and in concentrated solution in different solvents dioxane, dichloro ethane, dichloro propene... 

Dichloro-l,3,5-triazanaphthalene and its 6-methyl derivative react at the 4-position (70-90% yields) with ammonia in dioxane (20°, 15 min) or in water (95°, 1.5 hr) and with diethylamine in dioxane (20°, 15 min). The dichloroazine yields the 4-(A-ethyl-anilino)-2-chloro derivative under acidic conditions. Amination of the 2,4-dithioxo derivative with concentrated ammonia (95°,... 

Dichloro-2-phenylquinoxahne was completely unchanged by MeONa in refluxing MeOH-dioxane for 2 h. ... 

Dichloro-2-methyl-3-methylsulfonylquinoxahne 1,4-dioxide (63) gave 6,7-dichloro-2-(3-dimethylaminopropylamino)-3-methylquinoxahne 1,4-dioxide (64) (H2NCH2CH2CH2NMe2, CHCI3, dioxane, 20°C 80°C, 10 h 47%) or N, A -bis(6,7-dichloro-3-methyl-l,4-dioxidoquinoxaline-2-yl)hydrazme (65) (H2NNH2, EtOH, 20°C, 10 h 66%). ... 

D-lysergic acid propargylamide (0.016 mole) was dissolved in a mixture dichloro-methane/dioxane (85/15), 400 ml. Under vigorous stirring into this solution the polymer supported bromine (prepared acc. to ref. 29) containing 0.024... 

Bob Ardrey obtained a first degree in Chemistry from the University of Surrey where he went on to obtain his doctorate stndying the chemistry of trans-2,3-dichloro-l,4-dioxan and the stereochemistry of its reaction prodncts using primarily mass spectrometry and nnclear magnetic resonance spectroscopy. He then carried ont post-doctoral research at King s College, London, into the development of emitters for field-desorption mass spectrometry. 

It is believed that equatorial substituents such as chlorine or bromine would increase the guest diameter beyond the allowed values (assuming that the guest molecules stack roughly parallel to the canal68)). Support for this comes from the study of fluorocyclohexane where the population of the axial conformer is not enhanced to any major extent70. Nitro-71) and cyano-cyclohexane, trans-l,2-dichloro-, trans-1,2-dibromo-, tram-1,4-dichloro-, trans-1,4-dibromo-, and trans-l-bromo-4-chloro-cyclohexane all pack most efficiently in the thiourea canals as the axial or diaxial conformer 68,72. Tram-2,3-dichloro-1,4-dioxane behaves similarly73. In contrast isocyanato-, tram-1,4-diiodo-, trans-1 -bromo-4-iodo-, and tram-1 -chloro-4-iodo-cyclohexane are present as mixtures of the axial/equatorial or diaxial/diequatorial conformations as appropriate 68,72). The reason for this anomalous behaviour of the iodosubstituted cyclohexanes is not clear. 

Haszeldine, R. N. et al., J. Chem. Soc., 1959, 1085-1086 1,1,1-Trichloroethane exploded after heating under oxygen at 54 bar and 100°C for 3 h [1], Trichloroethylene, remaining in a pipe after cleaning operations, exploded under 27 bar pressure of oxygen at ambient temperature. It was later found possible to explode stoicheiometric mixtures [2], Chlorotrifluoroethylene and bromotriflu-oroethylene each react explosively with oxygen at ambient temperature [3], but controlled oxidation of the former produces an explosive cyclic peroxide, 4.5-dichloro-3,3,4,5,6,6-hexafluoro-1,2-dioxane [4]. 

Compounds in which the carbons are sp3 hybridized display the same confused situation. Erickson 78> reports that the trans vicinal H—H coupling constant of c//-dibromosuccinic anhydride (which is reasonably rigid) varies from 2.5 Hz in CHC13 to 6.0 Hz in acetone and dioxane. The same paper reports that the meso dibromosuccinic anhydride and the two corresponding dichloro compounds do not display any solvent dependence of their coupling constants. (Erickson also reports that lJc.H of the dl- dibromide decreases from 172 Hz in chloroform to 166 Hz in acetone and 165 Hz in dioxane exactly the opposite behavior from that observed for any other 1JC H coupling ever studied). It is at least possible that these data result from chemical degradation of the solute rather than from true solvent effects as discussed here. 

The molecules of trans-2,3- and -2,5-dichloro-l, 4-dioxanes in the crystal are in the chair conformation with both chlorine atoms occupying axial positions (29). In solution, too, there is a preference for this conformation however, the dipole moment for the former molecule in solution is higher than expected for the purely diaxial conformation (30). 

A solution of 100 mg. (0.41 mmole) of 4,4 -dimethoxybibenzyl (Note 1) in 1.5 ml. of anhydrous dioxane (Note 2) was placed in a 10-ml. round-bottomed flask. To this was added 103 mg. (0.45 mmole) of 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ Note 3) dissolved in 1.5 ml. of anhydrous dioxane. The flask was fitted with a reflux condenser and heated in an oil bath at 105° for 18 hours. The solution, which was initially deep green, became pale yellow as the hydroquinone crystallized out. The mixture was cooled, and the solid was filtered off. It was washed with 1 ml. of warm benzene followed by 6 ml. of warm chloro-... 

In trans-2,3-di-F- and rrans-2,3-di-Cl-l,4-dioxane, as in the OR analogs, the halogens adopt the diaxial conformation [79NJC145, 79JOC2274 84SPL307]. The corresponding cis isomers, c/s-rrans-2,3,5,6-tetrachloro-, trans-anti-trans-2,3,5,6-tetTachloTO-, 2,2,3,3-tetrachloro-, and 2,2-dichloro-... 

Hydroxy-l,2,3,4-tetrahydroquinolines 304 were obtained by cyclization of oxime 2,4-dinitrophenyl ethers 303 in the presence of system NaBH3CN/NaH/l,4-dioxane (equation 131) . If the reductive cyclization was followed by oxidation with DDQ (2,3-dichloro-4,5-dicyano-p-benzoquinone) the corresponding 8-hydroxyquinolines 305 were obtained . ... 

Halogenation of dibenzofuran produces the 2-halo compounds. Bromina-tion can be achieved in good yield with bromine in acetic acid " or with N-bromosuccinimide in boiling carbon tetrachloride. The 2,8-dibromo compound has been made, using dioxane dibromide. Chlorination of dibenzofuran in acetic acid in the presence of iron powder can be controlled to yield the 2-chloro or the 2,8-dichloro compounds. 2-Chlorodi-benzofuran is best prepared by reaction of dibenzofuran with phosphorus pentachloride. 2-Iododibenzofuran (45%) results from treatment of dibenzofuran with iodine in boiling chloroform in the presence of nitric acid. 2,8-Diododibenzofuran is best prepared by reaction of dibenzofuran with iodine and iodic acid in aqueous acetic acid. ... 

An interesting formation of a 1,3-dioxan -one from a geminal dichloride and salicylic acid is displayed in Scheme 103. Langer et al. have found that phthaloyl chloride cleanly reacted with salicylic acid. The product was not the expected nine-membered ring but spirotetracycle 219 in 82% yield. The product formation can be explained by assuming an initial equilibration of phthaloyl chloride and 3,3-dichloro-3//-isobenzofuran-l-one <2001EJ01511>. 

Dichloro-l,4-dioxane and 2,3-dibromo-l,4-dithiane react smoothly with tin dithiolates 95 in the presence of BF3 Et20 to give the corresponding tricyclic adducts 96 as single m-diastereoisomers in good yields <1998JOC3952>. 

Synthesis of 2,3-dihydro-l,4-dithiin 11 was accomplished from l,3-dithiol-2-one 247 in the presence of dibro-moethane and potassium hydroxide <1998JOG3952>, while reaction of 2,3-dichloro-l,4-dioxane with powdered Zn in hexamethylphosphoramide (HMPA) was used for the synthesis of 1,4-dioxene 10 <1998JPP10067773>. To obtain substituted 1,4-oxathianes, the hydrogenation of the corresponding partially saturated compounds has been employed <2001J(P1)2604>. 

In order to obviate the formation of a formic ester, the reaction of l,2 3,4-di-0-isopropylidene-a-D-galactopyranose (42) was performed in p-dioxane. The 6-chloro-6-deoxy derivative (45) was again obtained, but only in low yield the major product was assigned the novel structure of 6-0-(4,6-dichloro-l,3,5-triazin-2-yl)-l,2 3,4-di-0-isopropylidene-a-D-galactopyranose (54). 

Acrylonitrile 3 - Amino-1,2,4-triazole Carbon tetrachloride Chloroform 1,4-Dichloro-2-butene Dioxane Epichlorohydrin Ethylene dibromide Ethylenethiourea Lead chromate Methylenedianiline Styrene... 

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