Pyridine-iodine chloride

Batsanov, A.S., Howard, J.A.K., Lightfoot, A.P., Twiddle, S.J.R. and Whiting, A., Stereoselective chloro-deboronation reactions induced by substituted pyridine-iodine chloride complexes, Eur. J. Org. Chem. (9), 1876-1883 (2005). 

Electrophilic addition to 9-vinylcarbazole occurs in the Markovnikov sense, thus hydrogen chloride,hydrogen bromide,chlorine, and bromine in carbon tetrachloride, and iodine chloride in pyridine are recorded as adding with initial electrophilic attack at the methylene. Mercuric acetate in methanol gave 9-(2-acetoxymercuri-l-methoxyethyl)carbazole. Although 9-vinylcarbazole gave an iodohydrin, comparable reaction with methanolic sodium hypochlorite led to 9-(2-chlorovinyl)carbazole. Catalytic reduction of the latter produced 9-(2-chloroethyl)carbazole. Tri-phenyltin hydride gave 96. ... 

A very large number of complexes of pyridines and quinolines with all the halogens and interhalogen compounds are known, and as they have been enumerated elsewhere (74HQ14-S2)407,77HC(32-1)319) just a few examples are illustrated (Scheme 14). Treatment of pyridine with chlorine or bromine in the presence of aluminum chloride yields 4-pyridylpyridinium salts (equation 29), but rather curiously the action of iodine chloride on pyridinium hydrochloride at 250 °C produces the 2-isomer (51 equation 30). 

Many reagents convert primary amines into nitriles. Some of these have been mentioned above and represent serious limitations on methods for generating carbonyl compounds. Other ways of oxidizing amines to nitriles are the use of nickel peroxide,lead tetraacetate," copper(I) chloride plus oxygen and pyridine," iodine pentafluoride and benzeneseleninic anhydride. double bromination-dehy-drobromination can be effected for the preparation of nitriles with 2 equiv. of NBS and trimethyl-amine. Likewise, fluorination and elimination of HP gives nitriles." ... 

Several papers on the chemistry of longifolene derivatives have been published. These include the conversion of the two half-esters (225) and (226) into the same olefinic ester (227) with Pb(OAc)4-Cu(OAc)2, the reaction of longifolene (228) with mercuric acetate followed by iodine chloride to give (229) and (230), and the reaction of longicyclene (231) with bromine in pyridine and iodine chloride-pyridine complex in acetic acid to yield (232) and (233) respectively. 

Dehydration Alumina (see also Dihydropyrane, preparation). Boric acid. Boron triSuoride. N-Bromoacetamide-Pyridine-SOj. Dicyclohexylcarbodiimide. Diketene. Dimethylform-amide-Thionyl chloride. Dimethyl sulfoxide. Ethylene chlorophosphite. Florisil. Girard s reagent. Hydrobromic acid. Iodine. Mesyl chloride-Sulfur dioxide. Methyl chlorosulfite. Methylketene diethylacetal. Naphthalene-d-sulfonic acid. Oxalic acid. Phenyl isocyanate. Phosgene. Phosphorus pentoxide. Phosphoryl chloride. Phthalic anhydride. Potassium bisulfate. Pyridine. Thionyi chloride. Thoria. p-Toluenesulfonic acid. p-Toluenesulfonyl chloride. Triphenylphosphine dibromide. 

Dehydration Alumina. Alumina-Pyridine-Diluent (sand). Dicyclohexylcarbodiimide. N,N-Diethyl-l-propynylamine. Dimethyl sulfoxide. Diphenylcarbodiimide. Iodine. Methoxya-cetylene. Oxalic acid. Phenylcyanate. Phosphorus pentoxide-t-Amine. Phosphoryl chloride-Phosphoric acid-Phosphorus pentoxide. Phosphoryl chloride-Pyridine. Thionyl chloride. 

P(C3H3N)]C1 or mCsHsNiai Monopyridineiodine(I) chloride or chloro(pyridine)iodine-(I), 7 176... 

Several new methods for the preparation of 1-haloalkynes have been described. High yields of bromo compounds, e.g. 28, are obtained by treatment of alkynes with triphenylphosphine/carbon tetrabromide, or with a concentrated aqueous solution of potassium hypobromite and potassium hydroxide (equation 1). 1-Iodoalkynes are produced from terminal alkynes and bis(pyridine)iodine(I) tetrafluoroborate in methanol in the presence of sodium methoxide (equation 2) or from alkynes with a mixture of iodine, potassium carbonate, copper(I) iodide and tetrabutylammonium chloride under phase-transfer catalysis. Lithium acetylides 29 (R = Ph, t-Bu, HOCH2 etc.) react with zinc iodide and bis(trimethylsilyl) peroxide to yield 1-iodoalkynes. The method has been... 

Oxidation of 1,4-Dihydropyridines to Pyridines with Stoichiometric Oxidants Many of the known stoichiometric oxidants were examined in the oxidation of 1,4-dihydropyridines to the corresponding pyridines. Thus, halogen-based oxidants, such as potassium bromate [251], sodium chlorite [252], calcium hypochlorite [253], iodic acid [254], its anhydride [255], iodine chloride [256], or hypervalent iodine species [257], give good results (Scheme 13.144). 

Reaction of the potassium salt of salicylaldehyde with chlo-roacetone affords first the corresponding phenolic ether aldol cyclization of the aldehyde with the ketonic side chain affords the benzofuran (1). Reduction of the carbonyl group by means of the Wolf-Kischner reaction affords 2-ethyl-benzofuran. Friedel-Crafts acylation with anisoyl chloride proceeds on the remaining unsubstituted position on the furan ring (2). The methyl ether is then cleaved by means of pyridine hydrochloride (3). lodina-tion of the phenol is accomplished by means of an alkaline solution of iodine and potassium iodide. There is thus obtained benziodarone (4)... 

Redox titrants (mainly in acetic acid) are bromine, iodine monochloride, chlorine dioxide, iodine (for Karl Fischer reagent based on a methanolic solution of iodine and S02 with pyridine, and the alternatives, methyl-Cellosolve instead of methanol, or sodium acetate instead of pyridine (see pp. 204-205), and other oxidants, mostly compounds of metals of high valency such as potassium permanganate, chromic acid, lead(IV) or mercury(II) acetate or cerium(IV) salts reductants include sodium dithionate, pyrocatechol and oxalic acid, and compounds of metals at low valency such as iron(II) perchlorate, tin(II) chloride, vanadyl acetate, arsenic(IV) or titanium(III) chloride and chromium(II) chloride. 

Only a little 3,5-di- and penta-iodopyridine is obtained when pyridine reacts with iodine in the vapour phase. Treatment of pyridine with iodine in 50% oleum furnishes 3-iodo-(18%) and some 3,5-di-iodo-pyridine. This is probably the result of electrophilic substitution by I+, with oleum performing in the role already discussed (57JCS387). The products of iodination of quinoline are not well defined however, a reviewer (77HC(32-1)319) has pointed out that one such product (formed by heating quinoline with iodine and potassium iodide at 160-170 °C in the presence of mercury(II) chloride) has a melting point identical with that of 3-iodoquinoline. 

To a stirred solution of 120 ml of methylene chloride, 18 ml of dry pyridine, and 5 ml of iodine pentafluoride maintained at —10°C to —20°C in a Dry Ice-carbon tetrachloride slurry is added a solution of 13.5 gm (0.1 mole) of cumyl-amine in 10 ml of methylene chloride over a 1 hr period. The reaction mixture is stirred for another hour at —10°C, and then for 1 hr at 0°. After this time, water is added to the reaction mixture and stirring is continued until the yellow solid which had formed is dissolved. The lower organic layer is separated and washed in turn with water, 1 N hydrochloric acid, a saturated sodium thiosulfate solution, and again with water. After drying with anhydrous magnesium sulfate and filtration, the product solution is partially evaporated by means of a rotary evaporator at a temperature below 30°C. The brown solid obtained on cooling is separated and recrystallized twice from methylene chloride yield 4.75 gm (17.9%), m.p. 86.9°-88.7°C. 

Excess pyridine was distilled from the flask, and the resulting product was dried under high vacuum at room temperature to a constant weight. The amount of pyridine utilized in the reaction could then be determined by weight difference before and after reaction. Complete analytical results for the crude products obtained with the chlorides and oromides are given in Table II. Because the tantalum(V) and niobium(V) iodides both yielded free iodine in the reaction with pyridine, their products were washed with chloroform, as described later, before analysis. 

Solvent systems used for thin layer chromatography were 1) n-butanol acetic acidiwater (4 1 5 upper phase), 2) acetic acid water (15 85), 3) ethyl acetate pyridine water (12 5 4), and 4) chloroform acetic acid water (50 45 5). Silica gel plates were used for chromatography of flavonoid aglycones and cellulose plates for all other components. Aluminum chloride was used for detection (under long UV light) of flavonoids, aniline phthalate for sugars, ninhydrin for amino acids and iodine for other components. Cellulose thick layer plates were developed with solvents 1 or 2. 

Similarly with the raising of the b.p. in violet or reddish-violet soln. of iodine in benzophenone, carbon disulphide, ethyl chloride, chloroform, carbon tetrachloride, ethylene chloride or benzene or in brown soln. of ethyl alcohol, methyl alcohol, thymol, ethyl ether, methylal, or acetone. The values for the last three solvents were rather low, presumably because of the chemical action of solute on solvent. High values with benzene are attributed to the formation of a solid soln. of solvent and solid. Confirmatory results were found by J. Hertz with naphthalene, and by E. Beckmann and P. Wantig with pyridine. The results by I. von Ostromisslensky (o-nitrotoluene), by G. Kriiss and E. Thiele (glacial acetic acid), and by H. Gautier and G. Charpy indicate polymerization, but they are not considered to be reliable. 

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