Thomas H. Applewhite

Castor-based derivatives: Synthesis of some acrylate esters

Acrylate esters of various hydroxy acid derivatives obtainable from castor oil have been synthesized and characterized. Synthetic methods evaluated include acid- and base-catalyzed alcoholysis of methyl acrylate, esterification with acrylic acid, acrylyl chloride, or acrylic anhydride, and esterification with β-chloropropionyl chloride or anhydride followed by dehydrohalogenation. The two-step esterification-dehydrohalogenation procedure gives most satisfactory yields and purity. Preparation, purification, and characterization of the compounds are described and the various synthetic methods are evaluated.

Correction of dietary fat availability estimates for wastage of food service deep-frying fats

Because of the renewed interest in the consumption of hydrogenated fats, reliable estimates of the dietary fat available to the United States population require correction for the considerable amount of deep-frying fats used in food service operations that are discarded after use and thus are not available for consumption. We estimated this fat wastage from food service sources from published data on fat exchange during cooking and on numbers of specific entrees purchased away from the home by United States households. Among food items considered, fat rendered from hamburgers and chicken contributed substantially to the total gross fat available for discard; fried chicken, french fries and doughnuts accounted for a large portion of total fat uptake by foods. To calculate waste frying fat, expressed as a percent of net waste fat, we subtracted fat uptake by foods from the total visible frying fat available for usage and from the level of gross fat available for discard. Dividing the resulting values gave a percent waste frying fat of 60%. For calculation of fat available for consumption, we recommend that contributions from deep-frying fats be reduced by 50% of the total available to correct for wastage. This value is conservative and representative of actual experience of major food service operations and agrees closely with estimates derived from spent grease recovery reported in the United States.

Conversion of methyl ricinoleate to methyl 12-ketostearate with Raney nickel

A convenient laboratory preparation of methyl 12-ketostearate is described. Methyl ricinoleate is converted to methyl 12-ketostearate in 70–75% yield by Raney nickel. The type and quantity of Raney nickel have a marked influence on the yield as well as on the time and temp required for the conversion. The reaction is not a direct isomerization as previously assumed but appears to be a two-step process. Methyl ricinoleate is hydrogenated rapidly to methyl 12-hydroxystearate which is then dehydrogenated slowly to the product. Hydrogenolysis of the alcohol function is a competing reaction which is minimized by the proper choice of reaction conditions.

Saturated keto esters from lesquerolic, dimorphecolic, and densipolic acids

SummaryThe naturally occurring, unsaturated, hydroxy fatty esters, methyl lesquerolate (methyl 14-hydroxy-cis-11-eicosenoate), methyl dimorphecolate (methyl 9-hydroxy-trans, trans-10,12-octadecadienoate), and methyl densipolate (methyl 12-hydroxy-cis,cis-9,15-octadecadienoate) have been converted to the corresponding saturated keto esters by tow routes. The unsaturated esters were subjected to a hydrogenation-dehydrogenation reaction in the presence of Raney nickel or their saturated derivatives were dehydrogenated by copper chromite catalysis. Yields of the keto esters are 65–82% in the nickel-catalyzed reactions, and 71–94% by copper chromite-catalyzed dehydrogenation. In the hydrogenation-dehydrogenation system the order of reactivity is: methyl lesquerolate>methyl dimorphecolate>methyl densipolate. Relationships between structure and reactivity of these compounds, methyl 12-hydroxystearate, and methyl ricinoleate are discussed.

Castor-based derivatives: Synthesis of some amides

Various amides of ricinoleic acid and the related ricinelaidic, hydroxystearic, dihydroxystearic, and trihydroxystearic acids have been synthesized and characterized. Ester aminolysis in methanol solution with sodium methoxide catalyst at room temperature has limited utility since it suffers severe rate retadations due to steric effects with secondary amines. In addition, with primary amines and ammonia, extended reaction times are generally necessary for reasonable, yields. The use of mixed carboxylic-carbonic anhydrides in amide syntheses was investigated and found applicable without interference from the secondary hydroxyl groups. Also, no appreciable steric effects were observed with most amines. This rapid, high yield method has been employed in the synthesis of a number of new amides from castor-based acids, ammonia, and primary and secondary amines.

Dehydrogenation of methyl 12-hydroxystearate to methyl 12-ketostearate with Raney nickel

Suitable conditions have been found for the dehydrogenation of methyl 12-hydroxystearate to methyl 12-ketostearate with Raney nickel. Crude reaction mixtures contained 95% product when analyzed by gas-liquid chromatography (GLC). Isolated yields were 83%. Both catalyst concentration and type strongly influence the reaction. Laboratory-made methyl 12-hydroxystearate gave significantly better yields than commercial material, but satisfactory conversions were obtained from citrate-free commercial material. The extent of the dehydrogenation was determined by hydrogen evolution and GLC. Synthetic and analytical techniques used in studying this reaction are discussed.

Catalytic dehydrogenation of methyl 12-hydroxystearate to methyl 12-ketostearate

Economically attractive catalytic methods for the conversion of methyl 12-hydroxystearate to methyl 12-ketostearate have been developed on a laboratory scale. With 1.0 wt% copper chromite catalyst, pure methyl 12-hydroxystearate is dehydrogenated at 180–263C to methyl 12-ketostearate in 99% yield and 97% purity. Commercial methyl 12-hydroxystearate required 3% catalyst but gave a 98% conversion to product and 100% crude yield.

Some new derivatives of lesquerolic acid

A series of derivatives was prepared for evaluation purposes from lesquerolic (14-hydroxy-cis-11-eicosenoic) acid. Preparative procedures, isolation, and purification of these materials are reported, and the new derivatives described.