Sodium dichromate alcohols

By the controlled oxidation of primary alcohols with a solution of potassium or sodium dichromate in dilute sulphuric acid. To avoid the further oxidation to the corresponding acid, the aldehyde is removed as rapidly as possible by distillation through a fractionating column, for example ... 

Methyl ethyl ketone. Use the apparatus of Fig. Ill, 61, 1 but with a 500 ml. round-bottomed flask. Place 40 g. (50 ml.) of see. butyl alcohol, 100 ml. of water and a few fragments of porous porcelain in the flask. Dissolve 100 g. of sodium dichromate dihydrate in 125 ml. of water in a beaker and add very slowly and with constant sturing 80 ml. of concentrated sulphuric acid allow to cool, and transfer the resulting solution to the dropping funnel. Heat the flask on a wire gauze or in an air bath until the alcohol mixture commences to boil. Remove the flame and run in the dichromate solution slowly and at such a rate that the temperature... 

The synthesis of fluoroalkyl and chloroalkyl fluoromethyl ketones is achieved by oxidation of the corresponding alcohols by sodium dichromate and sulfunc acid in methylene chlonde in the presence of a phase transfer catalyst [49] (equation 45)... 

Write the structural formula for the product of (a) the reaction of glycerol (1,2,3-trihydroxypropane) with stearic acid, CH5(CH2)16COOH, to produce a saturated fat (b) the oxidation of 4-hydroxybenzyl alcohol by sodium dichromate in an acidic organic solvent. 

Propionaldehyde. Use 34 g. (42-6 ml.) of n-propyl alcohol, and a solution containing 56 g. of sodium dichromate dihydrate, 300 ml. of water and 40 ml. of concentrated sulphuric acid. The experimental details are identical with those for n-butyraldehyde, except that the addition of the dichromate solution occupies 20 minutes, the temperature at the top of the column is not allowed to rise above 70-76°, and during the subsequent heating for 15 minutes the liquid passing over below 80° is collected the receiver must be cooled in ice. The yield of propionaldehyde, b.p. 47-50°, is 12 g. 

Alcohol (125 c.c. 2 moles C2H5OH) is now poured into the flask along with about one-third of a mixture of 150 c.c. (270 g.) of sulphuric acid and 250 c.c. of water and this alcohol-sulphuric acid-water mixture is heated to boiling. To the main portion of the diluted sulphuric acid 100 c.c. of water are added, 200 g. of sodium dichromate are dissolved in the liquid so prepared, and the solution is poured while still warm into the dropping funnel, the delivery tube of which is completely filled. After the funnel has been fixed in position its contents are allowed to run at a moderate speed into the... 

The mixture of alcohols is placed in a 1000-mL round-bottomed flask, dissolved in 300 mL of ether, and cooled to 0°C. To this solution is added via an addition funnel over a 30-min period a mixture of sodium dichromate dihydrate (27.5 g, 0.092 mol), 100 mL of water, and 10.2 mL of coned sulfuric acid. The mixture is stirred at 0°C for 1 hr, warmed to room temperature where stirring is maintained overnight, diluted with 200 mL of water, and poured into a separatory funnel. The layers are separated and the aqueous phase is extracted with ether (3 x 200 mL). The combined organic layers are washed with saturated sodium bicarbonate solution (200 mL) and brine (200 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated by rotary evaporation to give 16.8-17.8 g (61-65%) of verbenone (Note 7). Final purification is achieved by distillation of the oil through a 5-in Vigreux column at reduced pressure (dry ice-acetone cooled receiver) 13.1 g (47%), bp 108-110°C (5 mm) (Note 8). 

If the ratios of the starting materials are changed slightly the yield of ester is further increased. Thus when 148 g. (2 moles) of n-butyl alcohol, 187 g. (0.62 mole) of crystallized sodium dichromate and 500 g. (5.1 moles) of sulfuric acid (sp. g. 1.84) are used and the reaction mixture heated after the addition of the butyl alcohol the yield of ester is 57-61 g. (70-75 per cent of the theoretical amount). (Private communication from W. J. Hickinbottom.) (Compare also Reilly and Hickinbottom, Scientific Proceedings of the Royal Dublin Society, 16, 246 (1921).)... 

In tonnage production, acetaldehyde may be manufactured by (1) the direct oxidation of ethylene, requiring a catalytic solution of copper chloride plus small quantities of palladium chloride, (2) the oxidation of ethyl alcohol with sodium dichromate, and (3) the dry distillation of calcium acetate with calcium formate. 

Laboratory oxidation of alcohols most often is carried out with chromic acid (H2Cr04), which usually is prepared as required from chromic oxide (Cr03) or from sodium dichromate (Na2Cr207) in combination with sulfuric acid. Ethanoic (acetic) acid is a useful solvent for such reactions ... 

To 80 gms. (excess) of finely powdered potassium or sodium dichromate, and 100 gms. of 50% sulphuric acid placed in a reflux apparatus (see p. 212), 70 gms. (1 mol.) of 25% alcohol are slowly added. The mixture is heated for 30 minutes and distilled until only very little acid passes over. The distillate is neutralised with caustic potash, and evaporated to dryness on a water bath. The residue is powdered and distilled with cone. 

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