Oxidation with Mercuric Oxide

A mixture of 13 g (0.066 mol) of benzophenone bydrazone, 15 g of anhydrous sodium sulfate, 35 g (0.16 mol) of yellow (or red) mercuric oxide, 200 mL of dry ether, and 5 mL (10 mL if red mercuric oxide is used) of ethanol saturated with potassium hydroxide is shaken for 75 min in a pressure bottle wrapped in a wet towel. The reaction mixture is filtered, and the solvent is evaporated under reduced pressure at room temperature. The dark red oil thus obtained is dissolved in petroleum ether (bp 30-60 °C), and the solution is filtered again. Removal of the solvent from the filtrate under reduced pressure at room temperature gives an oil, which crystallizes when frozen in a stoppered flask in dry ice. After the flask has warmed to room temperature, the dark-red crystals are spread over a porous plate to give 11.4 g (89%) of dipbenyldiazometbane, mp 29-30 °C. 

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Aminotriazoles and their derivatives can be prepared from bis hydrazones and from substituted bis hydrazones of a-diketones. The bis hydrazones may in some cases be prepared more conveniently from -bromoketones than from a-diketones. Oxidation with mercuric oxide or with manganese dioxide gives the 1-aminotriazoles directly (Scheme m-ns Although two isomeric triazoles would be ex-... 

Azoalkanes have also been produced by oxidation with mercuric oxide. This reagent is considered the reagent of choice for azoalkanes [76, 87, 93], as well as for the preparation of cyclic azo compounds [94], and 1-pyrazolines [95a]. When used in the preparation of a-carbonyl azo compounds, evidently mercury complexes are formed with the diacylhydrazine starting materials. These complexes are then treated with halogens (iodine or chlorine) to produce the azo compounds [92]. 

By more cautious oxidation with mercuric oxide, copper sulphate or ferric chloride, the salts of phenyl hydrazine yield salts of diazo benzene. 

Of aromatic ketone hydrazones, benzophenone hydrazone is oxidized with yellow mercuric oxide [387, 390] or red mercuric oxide [387], fluo-renone hydrazone is oxidized with mercuric oxide [5SS] or nickel peroxide [935], and di-a-thienyl ketone hydrazone and phenyl naphthyl ketone hydrazones are oxidized with silver oxide or manganese dioxide [370] (equations 459-461). 

Treatment of phenylarsenious oxide with mercuric oxide under alkaline conditions gives diphenylmercury (259). Dichlorophenylarsine and mercuric chloride do not react in refluxing ethanol (260) Lowe and... 

The reactions of dienes of the type of (301, R = H n = 1, 2) with an excess of dimethyl azobiscarboxylate leads to the formation of l 2-adducts the hydrolytic decarboxylation of which by boiling with hydrazine hydrate and oxidation with mercuric oxide gives compounds of the type of (305 n = 1, 2), which are derivatives of 11,12-diazasteroids. Their yield with n = 1 amounts to 34% and with n = 2 to 48% on the corresponding derivatives (301) [404]. 

Action of dilute sulfuric acid for a short period of time afforded a crystalline disaccharide (Vb), in a 20 to 30 % yield. It contained equal amounts of d-glucosamine and D-glucuronic add, and a free amino group. Esterification of the carboxyl group, followed by oxidation with mercuric oxide, gave the... 

Phenylbenzoyldiazomethane may be prepared by the oxidation of benzil-monohydrazone with mercuric oxide in the presence of dry etber as a solvent Tbe addition of a little alcoholic potassium hydroxide serves to catalyse the reaction ... 

Unsaturation value can be determined by the reaction of the akyl or propenyl end group with mercuric acetate ia a methanolic solution to give acetoxymercuric methoxy compounds and acetic acid (ASTM D4671-87). The amount of acetic acid released ia this equimolar reaction is determined by titration with standard alcohoHc potassium hydroxide. Sodium bromide is normally added to convert the iasoluble mercuric oxide (a titration iaterference) to mercuric bromide. The value is usually expressed as meg KOH/g polyol which can be converted to OH No. units usiag multiplication by 56.1 or to percentage of vinyl usiag multiplication by 2.7. 

Methylation of avermectins B and B2 leads to the corresponding derivatives of the A series (49). A procedure involving the oxidation of the 5-methoxy group with mercuric acetate and NaBH reduction of the 5-keto-intermediate allows the conversion of the A to the B components (50). The 23-hydroxy group of the "2" components, after selective protection of the other secondary hydroxy groups, is converted to a thionocarbonate, which can be elirninated to give the 22,23-double bond of the "1" components alternatively it can be reduced with tributyltin hydride to the 22,23-dihydro derivatives (= ivermectins) (51). 

Other ions, eg, ferrate, chloride, and formate, are determined by first removing the cyanide ion at ca pH 3.5 (methyl orange end point). Iron is titrated, using thioglycolic acid, and the optical density of the resulting pink solution is measured at 538 nm. Formate is oxidized by titration with mercuric chloride. The mercurous chloride produced is determined gravimetricaHy. Chloride ion is determined by a titration with 0.1 Ai silver nitrate. The end point is determined electrometricaHy. 

Boil the solution with mercuric oxide a violet solution of murexide is formed. 

The substituted 1,2,3,4-letrahydroisoquinolines studied by Knabe and Roloff (87) also produce some puzzling results difficult to rationalize when oxidized with mercuric EDTA. Compounds 88 and 89 are not attacked to... 

It was found, during a study of synthetic routes leading to quinine analogues, that oxidation of a specific bicydic pyrazoline derivative with mercuric acetate gives an enamine-like pyrazole (87b). 

A -Piperideine-N-oxide was obtained along with a dimeric product by oxidation of N-hydroxypiperidines with mercuric acetate or potassium ferricyanide (107-109). 2l -Pyrroline-N-oxide is formed by oxidation of N-ethylpyrrolidine with hydrogen peroxide with simultaneous formation of ethylene (110). 

The 1,2-, 1,2,5-, 1,3,4-, and 1,2,5-substituted pyrrolidines afford the corresponding pyrrolines very readily by oxidation with mercuric acetate. In the case of 1,2,2-trimethylpyrrolidine (35), the formation of a double bond... 

The most general method for synthesis of cyclic enamines is the oxidation of tertiary amines with mercuric acetate, which has been investigated primarily by Leonard 111-116) and applied in numerous examples of structural investigation and in syntheses of alkaloids 102,117-121). The requirement of a tram-coplanar arrangement of an a proton and mercury complexed on nitrogen, in the optimum transition state, confers valuable selectivity to the reaction. It may thus be used as a kinetic probe for stereochemistry as well as for the formation of specific enamine isomers. 

The key step in syntheses of if/-quebrachamine (122-127) and if/-dihydro-cleavamine (12S) is the oxidation of tertiary amines with mercuric acetate to cyclic imonium salts, which give rise to an intramolecular electrophilic attack on an indole. 

The oxidation of unsymmetrical tertiary amines with mercuric acetate may also lead to isomeric enamines. In such cases, structures can often be established by NMR and IR spectra of the enamines and their corresponding imonium salts, through comparison with model systems (202-205). 

Recently, Kochetkov and Khomutova have reported on the mercuration of isoxazoles with mercuric acetate. The reaction occurs quite smoothly, more readily than for benzene derivatives and results in a 90-100% yield of 4-acetoxymercury derivatives (74) whose structure was proved by converting them to known 4-bromoisoxazoles (75). Under these reaction conditions isoxazole itself is oxidized by mercuric acetate, mercurous salts being thereby produced. 

The cyclized analog of meralluride is prepared by a similar synthesis. Thus, condensation of camphoric acid (42) (obtained by oxidation of camphor) with ammonia gives the bicyclic succinimide (44). Reaction with allyl isocyanate followed by ring opening and then reaction with mercuric acetate affords the mercury derivative (45) as the acetate rather than the hydroxide as above. Reaction with sodium chloride converts that acetate to the halide (46). Displacement on mercury with the disodium salt of thioglycollic acid affords the diuretic mercaptomerine (47). ... 

Dehydrogenation of the hydrazide derivative 33 with mercuric oxide in the presence of ethylene diamine tetraacetic acid (EDTA) gave 34 and 35 (77AP588). The latter (35) was prepared from a reaction of ester 36 with the appropriate lactam 37 (Scheme 11). 

Cyclization of hydrazone 38 with mercuric oxide and EDTA gave dihy-drotriazine 39 (87AP198). On the other hand, methyl hydrazone 38, under 4-electron withdrawal and neighboring group participation reacts with the same reagent to give lactam 40, a useful precursor for the synthesis of the pyrrolo[2,l-c]triazinium salt 41 by cyclization with perchloric acid (87AP258) (Scheme 12). 

The hydration of triple bonds is generally carried out with mercuric ion salts (often the sulfate or acetate) as catalysts. Mercuric oxide in the presence of an acid is also a common reagent. Since the addition follows Markovnikov s rule, only acetylene gives an aldehyde. All other triple-bond compounds give ketones (for a method of reversing the orientation for terminal alkynes, see 15-16). With allqmes of the form RC=CH methyl ketones are formed almost exclusively, but with RC=CR both possible products are usually obtained. The reaction can be conveniently carried out with a catalyst prepared by impregnating mercuric oxide onto Nafion-H (a superacidic perfluorinated resinsulfonic acid). ... 

A related method for conversion of carboxylic acids to bromides with decarboxylation is the Hunsdiecker reaction.276 The usual method for carrying out this transformation involves heating the carboxylic acid with mercuric oxide and bromine. 

The earliest oxidations were effected with nitrous fumes and later with mercuric oxide and isoamyl nitrite.74 Lead tetraacetate in acetic acid is in many cases the reagent of choice, but the removal of by-products can present some difficulties.75 IV-Haloimides and amides in alcoholic solutions have been reported to yield essentially pure tetrazolium salts76 and have been found specially useful in the preparation of heteroaryl-substituted tetrazolium salt.77,78 The novel formazans 49 have been successfully oxidized to 50 using 7V-chloro succinimide (Eq. II).79 tert-Butyl hypo-... 

Diarylthioketones are converted in good yields into orthometallated complexes by diiron enneacarbonyl.141 These in turn can be transformed oxidatively (Ce4+) or photochemically into isobenzothiophenes (see Section IV,C,2), or by reaction with mercuric trifluoroacetate into isobenzofurans (Scheme 78)142 the formation of methoxy esters is a competing process in... 

A complex naturally occurring amino acid 5-hydroxypiperazic acid (5HyPip) 100 was prepared by a multistep procedure that included Diels-Alder addition of 2,4-pentadienoic acid to phthalazinedione 83a as a first step (Scheme 24). Adduct 97 was esterified and oxidized with mercuric acetate to 98, which on hydrogenation over rhodium on alumina and subsequent hydrolysis provided a mixture of enantiomers from which the required enantiomer 99 was obtained by resolution with quinine. Its hydrazinolysis provided 100 [71JCS(C)514 77H119],... 

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