Chromous acetate

Isophorone usually contains 2—5% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). The term a-isophorone is sometimes used ia referring to the a,P-unsaturated ketone, whereas P-isophorone connotes the unconjugated derivative. P-lsophorone (bp 186°C) is lower boiling than isophorone and can be converted to isophorone by distilling at reduced pressure ia the presence of -toluenesulfonic acid (188). Isophorone can be converted to P-isophorone by treatment with adipic acid (189) or H on(Ill) acetylacetoate (190). P-lsophorone can also be prepared from 4-bromoisophorone by reduction with chromous acetate (191). P-lsophorone can be used as an iatermediate ia the synthesis of carotenoids (192). 

AC2O, 20° Cr(OAc)2/THF-H20, 25-65°, 75-95% yield. Chromous acetate also cleaves unsubstituted oximes, but the reaction is slow and requires... 

A new synthesis of substituted 1,3-dienes by reductive elimination of allylic nitro derivatives has been reported (Eq. 7.134).180 Tertiary allylic nitro compounds, bearing an acetate group in the (3-position, smoothly undergo reductive elimination to give conjugated 1,3-dienes when treated with chromous acetate and 2,2-dipyridine in DMF at 111-120 °C. 

Zard and coworkers have developed a synthesis of substituted dienes by reductive elimination of allylic nitroacetates (equation 33)66. Allylic nitroacetates can be prepared by condensation of nitromethane with the carbonyl compound followed by addition of formaldehyde and acetylation67. Reductive elimination can be carried out by employing either chromous acetate or samarium iodide. 

Divalent chromium salts show very strong reducing properties. They are prepared by reduction of chromium(III) compounds with zinc [187] or a zinc-copper couple and form dark blue solutions extremely sensitive to air. Most frequently used salts are chromous chloride [7SS], chromous sulfate [189], and less often chromous acetate. Reductions of organic compounds are carried out in homogeneous solutions in aqueous methanol [190], acetone [191], acetic acid [192], dimethylformamide [193] or tetrahydrofuran [194] (Procedure 37, p. 214). 

Additional Exercises Chromous acetate, Cr(C2H302)2 chromous sulfate, CrS04-7H20 chromous chloride, CrCl2-4H20 Anderson and Riffe, J. Ind. Eng. Chem., 8, 24 (1916) Reeoura, Ann. Chim. Phys., (6) 10, 6 (1887). 

It is well-known that an extensive chemistry of mononuclear chromium(II) exists in addition to the dimeric chemistry relevant to this review. Furthermore, oxidation of chromous acetate with a variety of oxidants has been shown to produce monomeric chromium(III) species. The rate law for disappearance of the chromous dimer has been interpreted as indicating that dissociation of the acetate dimer precedes the oxidation step (45). 

The preparation of chromous acetate, as it is usually carried out,1,2 depends upon the insolubility of the salt in cold water. Its preparation is sometimes troublesome because chromous compounds are extremely sensitive to atmospheric oxidation. 

A filtered solution of 84 g. of sodium acetate in 100 ml. of water is now introduced into the reaction flask through the funnel K, and the mixture is stirred for a short time. The liquid is filtered off, and the precipitate is washed with freshly boiled distilled water. If the chromous acetate is to be removed from the reaction flask, it must be thoroughly dried before exposure to the air, as it oxidizes much more rapidly when moist than when dry. The drying is carried out by washing the precipitate with alcohol and ether, the last traces of ether being removed by the stream of nitrogen. 

Chromous acetate is a deep-red powder, slightly soluble in cold water but readily soluble in hot water. It dissolves in and reacts with most acids. Even in the dry condition, it absorbs oxygen from the air. 

Chromous acetate is made as described in synthesis 45 and is cooled to 0°C. by immersing the reaction flask in an ice-salt mixture. The chromous acetate is dissolved in 60 ml. of previously cooled concentrated hydrochloric acid with stirring. A current of hydrogen chloride gas (see synthesis 52) is now passed through the flask along with the nitrogen for about one hour. Unless the current is... 

Cement, laboratory, 189 Cerium amalgam, 15 Cesium, metallic, 79 Chloroamine, 59 Chlorides, anhydrous, 28, 29 of silicon, 42 Chloroplumbic acid, 48 Chromi-oxalates, 37 Chromous acetate, 122 Chromous chloride, 124, 125 solution, 124 tetrahydrate, 126 trihydrate, 126 Cinnabar, 20 Cobalti-oxalates, 37... 

The partial synthesis from solasodine of nitrogen-containing analogues of ecdysone has been explored.22 In the successful route, 7V,0-diacetylsolasodine (16b) was treated with TV-bromo acetamide and HCI04. The bromohydrin (26a) that was formed was reductively debrominated with chromous acetate and butanethiol to... 

SYNS ACETIC ACID, CHROMIUiM (2+) SALT (SCI, 9CI) CHROMIUiM(2+) ACETATE CHROMIUM(II) ACETATE CHROMIUM DIACETATE CHROMOUS ACETATE CHROMOUS ACETATE MONOHYDRATE... 

Reduction of at,p-oxidoketones. In a study of potential routes to the A/B ring system of cardiac-active steroids (periplogenin, strophanthidin), Robinson and Henderson studied the reduction of 4/ ,5/ -oxidocholestane-3-onc (1) with chromous acetate. The best results were obtained by reduction of (I) with a large excess of freshly... 

Chromous Sulphate, CrSOi.VHgO, is produced by dissohdng chromous acetate in dilute sulphuric acid, or by interaction of chromium and sulphuric acid. It forms blue crystals, isomorphous with those of FeSO. THjO, and is soluble in water, though not in alcohol. It is readily oxidised by the oxygen of the air. Moissan describes a hydrate, CrSO. HgO, as a white powder, which with water regenerates the hepta-hydrate. ... 

A series of double carbonates has been prepared by acting on chromous acetate, or tartrate, mth alkali carbonates. ... 

Potassium Chromous Carbonate, KgCOg.CrCOg.SHgO, formed when chromous acetate is treated with a 20 per cent, solution of potassium carbonate, yields yellow hexagonal crystals. 

Sodium Chromous Carbonate, NaaCOj.CrCOj.lOHgO, separates as a reddish-brown powder when moist chromous acetate is mixed with a solution of sodium carbonate in an atmosphere of carbon dioxide. It yields microscopic, tabular, lozenge-shaped crystals. If heated at 100° C. in a current of a dry inert gas, the monohydrate, Na3CO3.CrCO3.H2O, is obtained. 

A red-brown magnesium compound has also been obtained. The carbonates of the alkaline earth metals have no action on chromous acetate. 

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