Dichlorous oxide

Base-catalyzed addition of glycosyl oxides for anomeric O-activation has been extended meanwhile to trifluoroacetonitrile (see Scheme 9), to dichlor-oacetonitrile, to l-aryl-l,l-dichloroacetonitriles, and to ketene imines (46,51,52). Also 2-(glycosyloxy)-pyridine and -pyrimidine derivatives were readily prepared from the corresponding 2-halo precursors (78). However,... 

The product is a mixture of stereoisomers. The chloro analog, antimetabolite acivicin, was prepared in a similar manner from vinylglycine and dichlor-oformaldoxime (80JOC4817 82TL4563). /3-Isoxazolylalanines were prepared by 1,3-dipolar cycloadditions of nitrile oxides to substituted acetamidomalonates (Scheme 23) (92JMC107). 

In contrast to the reactions of pyrans with electrophiles and nucleophiles, oxidations of 2-amino-4H-pyrans are represented by very few examples. Oxidizing of 281 into 2-iminopyrans 296 with chloroanil or dichlor-odicyanoquinone (DDQ) (04JME6299) can be used to protect the amino group in Sandmeyer reaction (297), or to introduce a methyl group into position 4 of pyran 298. The latter is essential because the corresponding acetophenones do not give 298 with MN and aminophenols (Scheme 125). 

Bis-[3,5-dichlor-2-hydroxy-phenyl -furoxan-2-oxid zuganglich. 

Bei der Oxidation von 1,2-Benzochinon-dioxim mit Dichlor-diselenan entsteht Benzofurazan-l-oxid als Nebenprodukt C.L. Pedersen, Acta Chem. Scand. 30B, 675 (1976). 

Die Oxidation von 2,4,5-Trimethyl-anilin mit Dihydrogenperoxid/Meerrettich-Peroxidase liefert 2,2, 4,4, 5,5 -Hexamethyl-azobenzol zu 25% neben einem Benzochinon5. Eine ahn-liche Oxidation findet auch statt, wenn Aniline, die in Kontaktherbiziden Verwendung finden (z.B. Propansaure-3,4-dichlor-anilid) in die Erde gelangen. Propansaure-3,4-di-chlor-anilid wird zunachst mikrobiologisch zu 3,4-Dichlor-anilin reduziert und anschlie-Bend durch Peroxidase-Reaktion in 3,3, 4,4 -Tetrachlor-azobenzol iibergefuhrt6. 

The most intriguing difference between the chemical properties of cyclopolysilanes and those of cycloalkanes is the ability of the former to form either anion or cation radicals upon one-electron reduction or oxidation, respectively. For example, the cyclic pentamer (Mc2Si)5 is reduced to the corresponding radical anion by sodium-potassium alloy in diethyl ether [see eqn (4.1) in Section 4.1.3], whereas the hexamer (Me2Si)6 is oxidised by aluminium trichloride in dichlor-omethane to the corresponding cation radical. In both cases the EPR spectra of the radical ions can be interpreted in terms of a-electron delocalisation over the entire polysilane ring (see Section 10.1.4.1). In this respect, the cyclosilanes resemble aromatic hydrocarbons rather than their aliphatic analogues. 

This oxidant is a bright-orange solid that is soluble in organic solvents, and very convenient to store and manipulate, because of its lack of hydro-philicity. Pyridinium dichromate (PDC), which is normally used in dichlor-omethane at room temperature, is a very efficient oxidant able to transform alcohols in aldehydes and ketones in high yield. The absence of water in the reaction media prevents the over-oxidation of aldehydes into carboxylic acids. 

In a subsequent report, in 2005 [55], the same group described the preparation of imprinted polymer capable of oxidising alcohols and alkanes with 2,6-dichlor-opyridine /V-oxide (86) without mineral acid activation. The polymer was imprinted with a ruthenium porphyrin complex (87) using the diphenylmethana-mine (88) as pseudo-substrate template in order to achieve a shape of the cavity complementary to the substrates, diphenylmethane (89) and diphenylmethanol (84). The reaction, carried out with the imprinted polymer on the diphenylmethanol as substrate, showed a rate enhancement 2.5 higher than with the non-imprinted polymer. In the same conditions, but with diphenylmethane and... 

Formation of sodium l,3-dichloro-l,3,5-triazine-2,4-dione-6-oxide ( sodium dichlor-oisocyanurate ) from an aqueous slurry of the trione, cyanuric acid and sodium hydroxide is accompanied by evolution of nitrogen trichloride. Nitrogen purging will keep the concentration of the explosive gas below the lower explosive limit of 5—6%. 

Bicyclo[2.2.1]heptadien setzt sich mit Dichlor-methyl-phosphan zu 4-Methyl-4-phospha-tetracyclo[3.3.0.O. O ctan -oxid urn196,197. Je nach Art der Reaktionsfiihrung werden unterschiedliche Anteile an exo/endo-Isomeven erhalten197 ... 

Bei der Hydrolyse von Dichlor-(l,l,2,2-tetrafluor-ethyl)-phosphan mit Wasser bei 25° und anschlieBender Oxidation mit Wasserstoffperoxid (10 Min. Erhitzen) erhaltman nach dem Eindampfen 94% 1,1,2,2-Tetrafluor-ethanphosphonsaure (Schmp. 50—51°)51, bei der Oxidation von 1-Amino-ethanphosphonigsaure mit Bromwasser 100% 1-Amino-ethanphosphonsdure (Schmp. 275-2770)52 ... 

Hydroxy-],3,2-benzodioxaphosphol-2-oxid (100% Schmp. 86°) entsteht bei der Hydrolyse des 2-Chlor-Derivats in 1,2-Dichlor-ethan mit der aquimolaren Menge wasser-freier Essigsaure96 ... 

Ausgehend von Phosphor(V)-chlorid erhalt man mit 3-Anilino-propannitril-Hydrochlo-rid (8071,2-Dichlor-ethan) ein Zwischenprodukt (70%), das mit Schwefeldioxid bei 0° zum 1-Phenyl-2,4,6-trichlor-l,2-dihydro-l,3,2-diazaphosphorin-2-oxid (50% Schmp. 102,5-105°) zersetzt wird395 ... 

Bis-[alkylthio]-l,3,2,4-diazadiphosphetidin-2,4-bis-oxide sind aus den entsprechenden 2,4-Dichlor-Derivaten mit Alkylthio-triraethyl-silan in hohen Ausbeuten zuganglich z.B.914 ... 

Methyl-l-phenyl-4,5-dihydro- -1-oxid E2, 46 aus Isopren/Dichlor-phenyl-phosphan und 2,6-Di-tert.-butyl-4-methyl-phenol E2, 30 3-Mcthyl-l-tetradecyl-4,5-dihydro- -1-oxid E2,... 

Chlor-4-phenyl- -2-oxid XII/2, 277 2-Chlor-4,4,6-trimethyl- -2-oxid XII/2, 277 2-(2,2-Dichlor-vinyloxy)-4-methyl- -2-oxid XII/2, 357... 

Rates of exchange with NaOMe/MeOH at 50°C of the 2-, 4-, and 6-positions of 3-chloropyridine N-oxide and of the 2-position of 3,5-dichlor-opyridine N-oxide, relative to the 2-position of pyridine N-oxide, were 1840, 0.37, 12.2, and 11,800, respectively. These showed that the normal carbanion mechanism applied and emphasized further the importance of inductive effects in base-catalyzed exchange. The activating effects of substituents (relative to a position in benzene, at 50°C) were calculated as 2-C1, 1800 4-C1, 9 2-N + 0, 3.8 x 109 4-N+0", 7.6 x 10s (69JOC1405). 

If air is blown simultaneously with the tetrachlormethane vapors against the incandescent wire, there is produced phosgene, which is probably formed by direct oxidation of dichlor-methylene ... 

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