In a
12-l. flask fitted with a
reflux condenser and an
efficient, liquid-sealed mechanical stirrer (Note
1) are placed
2.5 l. of 95 per cent ethyl alcohol,
872 g. (3.5 moles) of pure n-dodecyl bromide (
Org. Syn. Coll. Vol. I, 1941, 29, and
p. 246 above), and
278 g. (3.85 moles) of powdered 90 per cent potassium cyanide (Note
2). The mixture is refluxed for fifteen hours, with stirring, in a
water bath (Note
3). At the end of this time another
278-g. portion of potassium cyanide is added and the mixture refluxed, with stirring, for fifteen hours longer.
The flask is allowed to cool, and a solution of
670 g. of 90 per cent potassium hydroxide in 1 l. of water is added (Note
4). The solution is refluxed and stirred for thirty hours. The flask is fitted with a head for steam distillation (Note
5), and steam is passed in until foaming prevents further distillation. When the flask has cooled somewhat, the steam inlet is replaced by a
separatory funnel with a stem reaching to the bottom of the flask, and
1.5 l. of concentrated hydrochloric acid (sp. gr. 1.18) or the equivalent amount of more dilute acid is added. The flask is shaken occasionally to prevent stratification of the
hydrochloric acid. The
dropping funnel is then replaced by the steam inlet, and steam is passed through for about one-half hour. At the end of this time the water layer is siphoned off and discarded (Note
6).
The crude acid while still warm and fluid is treated with
815 cc. (14 moles) of 95 per cent ethyl alcohol containing 20–30 g. (3–5 per cent by weight) of anhydrous hydrogen chloride, and the solution is filtered from insoluble impurities. The filtrate is placed in a
3-l. flask fitted with a reflux condenser,
160 g. of anhydrous calcium chloride is added, and the mixture is refluxed for twenty-four hours (Note
7). The lower layer is siphoned off and diluted with twice its volume of water to recover any dissolved ester. The recovered ester is combined with the main portion,
408 cc. of alcohol containing 3–5 per cent of anhydrous hydrogen chloride and
80 g. of calcium chloride are added, and the mixture is refluxed for another twenty-four hours. The lower layer is siphoned off and the dissolved ester recovered as before. The upper layer is washed twice with an equal volume of warm water (30–40°) and transferred to a
2-l. separatory funnel; the volume of the oil is approximately 1 l. About 500 cc. of warm water and a few drops of
phenolphthalein are also placed in the funnel, and very dilute aqueous
ammonia (concentrated aqueous ammonia diluted with twenty volumes of water) is added, with shaking, until the resulting emulsion has a distinctly pink color (50–100 cc. is required).
Alcohol is added in portions of about 100 cc. until the emulsion is broken and the layers begin to separate quite rapidly; usually two or three additions of alcohol suffice. The lower layer is drawn off and set aside (Note
8). The oil is washed three times with warm water; if necessary, alcohol is added to break the emulsion. The ester is dried with anhydrous
calcium chloride, filtered, and distilled under reduced pressure. The yield of
ethyl tridecylate, b.p.
163–165°/5 mm. (
178–180°/20 mm.;
197–198°/60 mm.) is
615–660 g. (
73–78 per cent of the theoretical amount). By refractionating the fore- and after-runs, an additional
50–70 g. of product is obtained; 15–30 g. of ester and acid are recovered from the ammoniacal washings and from the
calcium chloride used to dry the main portion. The total yield is
685–710 g. (
81–84 per cent of the theoretical amount) (Note
9) and (Note
10).