Isopropyl alcohol, from acetone reduction

For reductive amination of acetone with ammonia two types of catalysts were designed (i) skeletal Ni catalyst prepared form a Ni-Al alloy and Ci) its tin modified versions. Both types of catalysts were used in a continuous flow gas phase reactor. The requirements for these catalysts were as follows high thermal and mechanical stability, high rates for the formation of both primary and secondary amines and suppression of the formation of isopropyl alcohol from acetone. 

Other Processes. Isopropyl alcohol can be prepared by the Hquid-phase oxidation of propane (118). It is produced iacidentaHy by the reductive condensation of acetone, and is pardy recovered from fermentation (119). Large-scale commercial biological production of isopropyl alcohol from carbohydrate raw materials has also been studied (120—123). 

Place 35 ml. of a M solution of aluminium tsopropoxide or 7 g. of solid aluminium tsopropoxide, 450 ml. of dry isopropyl alcohol and 21 g. of purified benzaldehyde (Section IV,115) in a 1 litre round-bottomed flask. Fit a short reflux condenser (no water in the cooling jacket) or better a Hahn condenser (2) (containing a 1 cm. layer of ethyl alcohol in the iimer tube) to the flask and arrange for slow distillation from a water bath at the rate of 3-6 drops per minute. Continue the heating until a negative test for acetone is obtained after 5 minutes of total reflux (6-9 hours) if the volume of the mixture falls below 200 ml. during the reduction, add more isopropyl alcohol. Remove the reflux or Hahn condenser and distil off (Fig. II, 13, 3) most of the isopropyl alcohol under atmospheric pressure from a suitable oil bath. Hydrolyse the... 

In 1904, Schardinger discovered the bacteriological formation of acetone from carbohydrates, and Pringsheim, in the years 1905-1909, described the reduction of carbohydrates to isopropyl alcohol and n-butyl alcohol. The subsequent work of Fernbach and Weizmann led to the development of an industry for the production of these substances by the fermentation of carbohydrates. ... 

The reduction of aldehydes and ketones is carried out very easily. The carbonyl compound and aluminum isopropoxide, prepared from aluminum and isopropyl alcohol, are heated in boiling isopropyl alcohol solution with provision for slow distillation until no more acetone is formed. The general equation may be represented as follows. 

Gobolos et al. studied reductive amination of acetone with ammonia in a flow system at 169-210°C and 0.8 MPa H2 (H2/NH3 = 0.5) on Raney Ni that had been modified by organic tin compounds with general formula of SnR l (R = Et, Bu, or benzyl) in order to suppress the formation of isopropyl alcohol.16 By introducing tin from tetraalkyl tin, the selectivity to the formation of secondary amine significantly increased at the expense of the primary amine (isopropylamine/diisopropylamine ratio = 68.2/24.1 at 192°C, compared to 83.6/8.6 at 190°C with unmodified catalyst). By modifying the catalyst with SnBzl2Cl2, the lowest selectivity (<1%) for the formation of isopropyl alcohol was obtained at temperatures of 171-202°C. The isopropy-lamine/diisopropylamine ratio was close to the values obtained on the unmodified catalyst (7.3% selectivity to isopropyl alcohol at 190°C). 

Isopropyl alcohol may be prepared from propylene by the catalytic reduction of acetone, or by fermentation of certain carbohydrates. 

It does not form, however, an addition-product with ammonia similar to that derived from aldehyde, but complex condensation products. When reduced by nascent hydrogen generated by the action of sodium amalgam on water, addition takes place as indicated above, and isopropyl alcohol is formed, but at the same time a dihydroxy alcohol, which contains six carbon atoms, is produced in appreciable quantities. This substance, called pinacol, is the first member of a series of such alcohols which are formed by the reduction of ketones. The equation for the reaction in the case of acetone is,... 

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