Copper sulfate-pyridine

The copper sulfate-pyridine mixture is readily reoxIdized by passing a current of air through it for thirty-six hours (Note 4). To this resulting solution is now added 200 g. of pyridine and it is then used for oxidizing another batch of 1696 g. of benzoin. 

In comparing the copper sulfate-pyridine method with the nitric acid method (Org. Syn. 1, 25) it should be pointed out that the constants on the samples are as follows ... 

In other words, by the nitric acid oxidation it is difficult to obtain a product completely free from benzoin. The yields by the nitric acid method are generally about 95-96 per cent, whereas with the copper sulfate-pyridine method the yield drops to approximately 86 per cent. 

Sulfuric acid, concentrated and dilute Silver nitrate Copper sulfate-pyridine test Cyanates, OCN Vigorous effervescence, due largely to evolution of carbon dioxide, with concentrated acid producing a more dramatic effect Curdy white precipitate of silver cyanate Lilac-blue precipitate (interference by thiocyanates) reagent is prepared by adding 2 or 3 drops of pyridine to 0.25 M CuS04 solution... 

Oxidation of 5-arylazo-6-aminoquinoline 146 with copper sulfate in pyridine gave the corresponding 2-aryltriazolo[4,5-/]quinolines 147. Condensation of halo-genated nitrobenzenes with triazolo[4,5-/]quinoline 145 yielded the appropriate 2H- and 3//-aryl derivatives. The nitration of 3-phenyl-3//-triazolo[4,5-/]quino-line 147 occurred at position 4 of the phenyl ring (Scheme 46) (73T221). 

Aminopyridine has been prepared by heating nicotinamide in an alkaline potassium hypobromite solution at 70° by hydrolysis of 8-pyridylurethan with oleum by heating 3-amino-pyridine-2-carboxylic acid at 250° by reduction of 3-nitro-pyridine with zinc and hydrochloric acid and by heating 3-bromopyridine with ammonia and copper sulfate in a sealed tube. ... 

A solution of 5g of copper sulfate 5-hydrate in 40-ml of water is mixed with 9g of fresh ammonium persulfate (or llg of the potassium salt) in 40ml of water. The mixture is cooled in ice and stirred while 15ml of pure pyridine are added drop by drop from a buret. The violet-blue crystalline precipitate is suction-filtered, washed with two 15ml portions of 10% aqueous pyridine, and finally dried in a desiccator (not in vacuo, as the product loses pyridine). 

Bromo-3-penten-2-one oxime 111 is converted into 2-hydroxypyrazole 1-oxides 112, when treated first with copper sulfate using pyridine as the solvent and then with butyl nitrite and aq KOH (1994JHC281, 1994JHC1487) (Scheme 34). 

To a solution of 1.14 g of 3-methyl-trans-4a-cisoid-4a,5a-cis-5a-l,4a,5,5a,10b,10c-hexahydro-7-dioxino[5,4-a]cyclopenta[b]benzofuranyl-methanol in 10 ml of dimethoxyethane cooled in an ice bath was added 0.43 ml of anhydrous pyridine and 0.38 ml ofthionyl chloride, and the mixture was stirred for 3 hours at room temperature. After addition of ether to the reaction mixture, the precipitate was filtered, and water was added to the filtrate and the mixture was extracted three times with ether. The extract was washed with aqueous saturated solution of copper sulfate, water, aqueous saturated solution of sodium hydrogen carbonate and aqueous saturated solution of sodium chloride, dried, and concentrated to give 1.2 g of crude crystals. The crude crystals were recrystallized from ethyl acetate-hexane to yield 1 g of the pure titled chloride (m.p. 94-95°C, yield 83%). 

A mixture of 2-chloroadenosine (13 g, 43 mM), 1,3-dichloro-l,1,3,3-tetraisopropyldisiloxane (15 g, 47.6 mM) and pyridine (150 mL) is stirred at room temperature under nitrogen for 3 hours. The solvent volume is reduced in vacuo and the resulting residue is dissolved in CH2CI2 (250 mL), washed with a saturated copper sulfate solution (2x150 mL) and dried with sodium sulfate. The organic layer is concentrated in vacuo and purified by column chromatography on silica gel (200 g) with ethyl acetate/hexane (1 1) to yield the title compound as a white powder (14.7 g, 63%, MP 198-200°C). NMR, IR and elemental analysis are confirmed the structure of the title compound. 

EPOXIDES Alumina. Bisfbenzonltrile)-dichloropalladium(H). Copper(II) sulfate-Pyridine. Diborane. Diphenyl d isu Ifide-Tri-n-bu t y Iphosphine. Organo-cuprates. Sodium cyanoborohydride. Sodium phenyl selenide. Trimethyl-sllyl phenyl sclcnidc. Trimethylsilyl trifluoromethanesulfonate. Triphenyl-phospliine-Thiocyanogen. 

Copper(I) f-butoxide, 122 Copper(I) chloride, 123 Copper(II) chloride, 123 Copper(I) cyanide, 124 Copper(I) iodide, 124-125 CoppeKil) sulfate, 389, 462 Copper(ll) sulfate-Pyridine, 125-126 Corey-Kim reagent. 111, 365 Crown ethers, 99-100,126, 356, 387, 389, 392... 

Hydration of aryl-substituted epoxides. Treatment of aryl-substituted oxiranes with copper(II) sulfate and pyridine in an aqueous phosphate buffer (pH 7) affords cis-diols by reaction of water at the benzylic position. Less than 15% of trans cleavage products obtain. In the absence of pyridine, the oxides are rapidly destroyed. Triethylamine cannot be substituted for pyridine. cis-Chlorohydrins are obtained when aryl-substituted oxides are treated with copper(II) sulfate, pyridine, and kiCl in THF, When methanol is used as solvent, the corresponding cis-glycol monomethyl ether is obtained. In all cases substitution occurs at the benzylic position. Alkyl oxiranes do not react under these conditions. ... 

C(S,v(c-DIOLS Copper(II) sulfate-Pyridine. ThalUum(l) acetate. 

The replacement of an aryl halogen atom by the cyano group can be accomplished by the action of anhydrous cuprous cyanide at 150-250° with or without an organic base (usually pyridine) as a promoter or solvent (Rosenmund-von Braun nitrile synthesis). The reaction is autocatalytic and may be accelerated by the addition of small amounts of a nitrile and Copper sulfate. Typical laboratory procedures are found in the syntheses of a-naphthonitrile (90%) and 9-cyanophenanthrene (87%). The adaptation of the process to commercial practice has been discussed. ... 

The dehydration of alcohols under mild conditions is affected by copper(II) Lewis acids. Copper sulfate has long been utilized as a dehydrating agent. An example of its effectiveness for alcohol dehydration is demonstrated in the conversion of the sensitive propargylic alcohol 1 to enyne 2 (Sch. 1) [4]. A carbocation mechanism is suggested by the formation of bis ethers in these reactions [5]. The addition of pyridine... 

A mixture of 158 g. (0.63 mole) of copper sulfate pentahydrate, 210 g. of pyridine, and 90 g. of water is stirred and heated on a water bath until the solid is in solution. To this is added 57.6 g. (0.3 mole) of furoin (p, 169), and heating and stirring are continued for 2 hours. 

Proteins respond to the following color tests (a) biuret, pink to purple with an excess of alkali and a small amount of copper sulfate (b) ninhydrin. a blue color when boiled with ninhydrin (triketohydrindene hydrate), which is intensified by the presence of pyridine (c) Millon s test for tyrosine, a brick-F color or precipitate when boiled with mercuric nitrate in an excess of nitric acid (d) Hopkins-Cole test for tryptophan, a violet zone with a salt of glyoxylic acid and stratified over sulfuric acid and (e) xanthoproteic test, a brilliant orange zone when a solution in concentrated nitric acid is stratified under ammonia. Almost all so-called alka-loidal reagents will precipitate proteins in slightly acid solution. 

Oxidation. Copper sulfate in pyridine-water oxidizes a-ketols to a-diketones) the spent solution can be reoxidized with air. ... 

Preparation.1 Ninety-six grams of anhydrous aluminum chloride is added to 320 ml- of pyridine containing 2.5% of water wanned to 50°. The resulting melt is heated at 70° with 2 g. of a copper catalyst (prepared from copper sulfate solution and zinc dust according to Brewster and Groening2). 

By earlier procedures benzoins were converted into diketones by nitric acid, but this dehydrogenation is better effected by means of copper compounds. For instance, benzoin itself gives 86% of benzil on treatment with copper sulfate in pyridine.440 Cholestenone has been prepared as follows by Diels and Abderhalden 441... 

For the preparation of aromatic cyanides from aromatic halides Rosenmund and von Braun introduced copper cyanide in place of the alkali cyanide the halide is warmed with copper cyanide, if necessary with addition of a little pyridine, at 150-250°. The reaction can be accelerated by small amounts of a nitrile or of copper sulfate.444... 

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