280 III. CHEMISTRY OF NEUTRAL FATS 



methanol solution, or as a fine powder, especially when suspended in xylene. 

 Eckey^^^ has reported that alkoxides of ethanol, isopropanol, ^erZ-butanol, 

 ethylene glycol, laurol and other alcohols, when suspended in xylene, have 

 approximately the same catalytic activity on a molecular basis as sodium 

 methoxide. The action of the catalyst can be immediately stopped by the 

 addition of water or of dilute acetic acid. 



(6) Directed Inter esterification. Under the usual conditions of perform- 

 ing an ester-ester interchange, either at high temperatures without a cat- 

 alytic agent or at lower temperatures with a catalyst, the net result of the 

 rearrangement is to change the fatty acid distribution in the mixed tri- 

 glycerides to a random one. However, when the reaction is performed at a 

 temperature sufl&ciently low so that one of the products formed can crystal- 

 lize from the molten mixture, the end product no longer involves a random 

 mixture but an extremely oriented product. Such a reaction is termed by 

 Eckey^^^ a "directed interesterification." 



Such directed ester-ester interchange can likewise be carried out some- 

 what more satisfactorily when inert solvents are used than with the molten 

 mixture. Eckey^®* has reported that pentane, hexane, benzene, and 

 toluene may serve well in that capacity. Lower temperatures are re- 

 quired when the reaction occurs in a solvent than when it takes place in the 

 melted fat. Since directed interesterification, to be effective, requires the 

 separation of a crystalline product, the volatile solvents are unsatisfactory 

 because the high-melting glycerides are more soluble in them. Alcohol 

 cannot be used, since the presence of this substance will cause an alcoholysis. 



Eckey^*^ found that, when cottonseed oil was subjected to undirected in- 

 teresterification at 120°F., the cloud point of the oil was increased only 

 from 27° to 56°F. On the other hand, when the directed procedure was 

 employed, the melting points of the resulting fat mixtures were much 

 higher. When the reactions Avere carried out at 70°, 60°, or 50°F. for 

 varying periods, maximum clouding temperatures were found to be 89°, 

 92°, and 89°F., respectively. The melting point of the solid phase which 

 crystallized out was 141°F., and its iodine number approached zero. 



By the application of directed interesterification, Eckey^^* has shown 

 that oils like cottonseed can be converted to a semi-solid type of shortening 

 without hydrogenation. Such a treated cottonseed fat has an iodine num- 

 ber and saponification value identical with that of the oil from which it 

 originated. Only the melting point and related properties are altered. 

 Under some conditions a shortening of this type may have an advantage 

 over the conventionally prepared hydrogenated fats in having a higher un- 

 saturated fatty acid content. However, this product does have the dis- 

 advantage of becoming rancid more readily, due to the presence of highly 

 unsaturated acids. 



Palm oil can be improved for use in blended shortenings by direct in- 



