Pyridine 1-oxide, 3,5-dimethyl

Pyridine 1-oxide, 3,5-dimethyl-kinetie data, 2, 197 (73JCS(P2)1065)... 

Substrates 1-3 are readily prepared with a few steps as illustrated in Scheme 4. After methylation of pyridine with dimethyl sulfate, oxidation with potassium ferricyanide in the presence of sodium hydroxide leads... 

A tricyclic heterocycle incorporating the pyridine oxide structure, compound 314, is produced from 3,5-dimethyl-4-nitroisoxazole (312) and 1-morpholinocyclopentene via the intermediate 313 (equation 128)156. 

The sulfur trioxide-pyridine activated dimethyl sulfoxide oxidation was also a key step in an excellent synthesis of the Pielog-Djerassi lactonic acid, being highly recommended as the test method to avoid epimerization of the C-2 center in the aldehyde (33). ... 

SAFETY PROFILE Poison by inhalation and ingestion. A corrosive eye, skin, and mucous membrane irritant. Potentially explosive reaction with water evolves hydrogen chloride and phosphine, which then ignites. Explosive reaction with 2,6-dimethylpyridine N-oxide, dimethyl sulfoxide, ferrocene-1,1 -dicarboxylic acid, pyridine N-oxide (above 60°C), sodium -L heat. Violent reaction or ignition with BI3, carbon disulfide, 2,5-dimethyl pyrrole + dimethyl formamide, organic matter, zinc powder. Reacts with water or steam to produce heat and toxic and corrosive fumes. Incompatible with carbon disulfide, N,N-dimethyl-formamide, 2,5-dimethylpyrrole, 2,6-dimethylpyridine N-oxide, dimethylsulfoxide, ferrocene-1,1-dicarboxylic acid, water, zinc. When heated to decomposition it emits highly toxic fumes of Cl" and POx. 

In contrast, the chemistry of the oxidation of a primary alcohol to an aldehyde differs sharply from the oxidation of an aldehyde to a carboxylic acid (case (b)). Advantage, in this case, must be taken of the difference in the mechanisms of these steps. Among the reagents which can effectively oxidize alcohols and remain rather inert toward aldehydes are pyridinium chlorochro-mate (a chromium trioxide-hydrogen chloride complex of pyridine) or dimethyl sulfoxide-Lewis acid. 

The oxidants dimethyl sulfoxide and nitroso compounds react easily with oL-bromo ketones and convert them into a-dicarbonyl compounds. The reaction with nitroso compounds is usually carried out in the presence of pyridine and proceeds through a nitrone stage. Phenacyl bromide (a-bromoacetophenone) is thus transformed first into phenacylpyridinium bromide and further, with nitrosobenzene, into a-ketoaldonitrone, which is subsequently treated with hydroxylamine to give phenylglyoxal monoxime or with phenylhydrazine to give phenylglyoxal osazone [985] (equation 411). 

Dehydrohalogenation Benzyltrimethylammonium mcsitoate. r-Butylamine. Calcium carbonate. j Uidine. Diazabicyclo[3.4.0]nonene-5. N.N-Dimethylaniline (see also Ethoxy-acetylene, preparation). N,N-Dimelhylformamide. Dimethyl sulfoxide-Potassium r-but-oxide. Dimethyl sulfoxide-Sodium bicarbonate. 2,4-Dinitrophenylhydrazine. Ethoxy-carbonylhydrazine. Ethyldicyclohexylamine. Ethyidiisopropylamine. Ion-exchange resins. Lithium. Lithium carbonate. Lithium carbonate-Lithium bromide. Lithium chloride. Methanolic KOH (see DimethylTormamide). N-PhenylmorphoKne. Potassium amide. Potassium r-butoxide. Pyridine. Quinoline. Rhodium-Alumina. Silver oxide. Sodium acetate-Acetonitrile (see Tetrachlorocyclopentadienone, preparation). Sodium amide. Sodium 2-butylcyclohexoxide. Sodium ethoxide (see l-Ethoxybutene-l-yne-3, preparation). Sodium hydride. Sodium iodide in 1,2-dimethoxyethane (see Tetrachlorocyclopentadienone, alternative preparation) Tetraethylammonium chloride. Tri-n-butylamine. Triethylamine. Tri-methyiamine (see Boron trichloride). Trimethyl phosphite. 

CI3OP Noncombustible liquid. Fumes in moist air. Contact with water, steam, or alcohols produces hydrochloric acid, phosphoric acid, and phosphine gas, which is pyrophoric, with possible ignition or explosion (may be a delayed reaction). Contact with air produces corrosive fumes. Violent reaction with acetone and possibly other ketones carbon disulfide, 2,6-dimethylpyridine-A-oxide, dimethyl sulfoxide, ethers (especially when metal salts are present) ferrocene-l,l -dicarboxylie acid, pyridine, zinc powder or dust. Reacts, possibly violently, with acids, bases, amines, amides, inorganic hydroxides alkali metals, alkalis, combustible materials, dimethyl... 

New spectroscopic data on the 1 2 adduct (18) of pyridine and dimethyl acetylenedicarboxylate have been reported together with the products derived from it by oxidation and by thermolysis. Oxidation with potassium dichromate yields a mixture of the indolizine (19) and the quinolizinone (20).38... 

Isotwistanol 273 (3.2.3.) was oxidized with pyridine-SOs/dimethyl sulfoxide to the ketone 341 (60%). NaBH4-reduction in 1,2-dimethoxyethane yielded exclusively the 10 -alcohol 342, which was acetylated (-> 323, see also 3.4.3.) and tosyl-... 

Other oxidation reactions using DMSO as an oxidant include the Pfitzner-Moffatt Oxidation (DMSO/dicyclohexylcarbodiimide), Swem oxidation (DMSO/oxalyl chloride or trifluoroacetic anhydride), Onodera oxidation (DMSO/phosphorus pentoxide), Parikh-Doering Oxidation (DMSO/pyridine-sulfur trioxide), Corey-Kim Oxidation (dimethyl sulfide/Ai-chlorosuccinimide), and Liu oxidation (DMSO/phenyl dichlorophosphate). 

ClaHi8Cl2N202Zn, Dichlorobis(2,6-lutidine N-oxide)zinc(II), 33B, 458 C1 aH2 2ClijCu2N20i S2, Di-jU (pyridine oxide)-bis(dichloro(dimethyl sulfoxide)copper(II)), 41B, 1120... 

Phosphoryl chloride Carbon disulflde, A,A-dimethylformamide, 2,5-dimethylpyrrole, 2,6-dimethyl-pyridine 1-oxide, dimethylsulfoxide, water, zinc... 

Organophosphorus Derivatives. Neopentyl glycol treated with pyridine and phosphorus trichloride in anhydrous dioxane yields the cycHc hydrogen phosphite, 5,5-dimethyl-l,3-dioxaphosphorinane 2-oxide (2) (32,33). Compounds of this type maybe useful as flameproofing plasticizers, stabilizers, synthetic lubricants, oil additives, pesticides, or intermediates for the preparation of other organophosphoms compounds (see Flame retardants Phosphorus compounds). 

Pyrrole oxidizes in air to red or black pigments of uncertain composition. More usehil is the preparation of 2-oxo-A -pyrrolines, which is best carried out by oxidation of the appropriate pyrrole with in pyridine (37), eg, 3,5-dimethyl-ethyl-3-pyrrolin-2-one [4030-24-4] from... 

Esters derived from the primary alcohols are the most stable and those derived from the tertiary alcohols are the least stable. The decomposition temperature is lower in polar solvents, eg, dimethyl sulfoxide (DMSO), with decomposition occurring at 20°C for esters derived from the tertiary alcohols (38). Esters of benzyl xanthic acid yield stilbenes on heating, and those from neopentyl alcohols thermally rearrange to the corresponding dithiol esters (39,40). The dialkyl xanthate esters catalytically rearrange to the dithiol esters with conventional Lewis acids or trifluoroacetic acid (41,42). The esters are also catalytically rearranged to the dithiolesters by pyridine Ai-oxide catalysts (43) ... 

Pyridine 1-oxide, 2,6-dimethyl-rate eonstants, 2, 190 (75JCS(P2)1600)... 

Pyrrolo[3,4-d]pyridazinium salts, 2,3-dimethyl-synthesis, 4, 291 Pyrrolo[ 1,2-6]pyridazinones oxidation, 4, 298 Pyrrolo[2,3-6]pyridine, 1-acetyl-cycloaddition reactions, 4, 509 Pyrrolo[2,3-6]pyridine, 3-bromo-nitration, 4, 505... 

The contents of the flask while still hot are poured into a 30-cm. evaporating dish and the alcohol is evaporated on a steam bath. The dry salt is pulverized and thoroughly mixed with 390 g. of calcium oxide, placed in a 2-I. copper retort (Note 3), and heated with the full flame of a Meker burner. The distillate is placed in a distilling flask and heated on a steam bath all material distilling under 90 is removed and discarded. The residue is then allowed to stand over solid potassium hydroxide for twelve hours and is finally fractionated. The dimethyl-pyridine distils at i42-i44°/743 mm. The yield is 35-36 g. or 62-64 per cent of the theoretical amount based on the 3,5-dicarb-ethoxy-2,6-dimethylpyridine, or 30-36 per cent based on the original ethyl acetoacetate. 

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