B:
Transfer 40 mL of water and 10 g of calcium undecylenate to a 250-mL separator. Cautiously and slowly add 10 mL of hydrochloric acid, while swirling. Insert the stopper, and shake.
[NOTE—The separator will become quite warm, and pressure must be carefully and frequently relieved through the stopcock. If a curdy, white material remains after 5 minutes of shaking, add additional hydrochloric acid, 1 mL at a time, and shake until a clear oily phase is formed.
] Allow the phases to separate, drain, and discard the bottom aqueous layer. Drain and discard the middle oily layer, if present. Filter the top layer of undecylenic acid through a pledget of cotton into a 10-mL graduated cylinder, noting the volume obtained. Transfer the filtrate to a 250-mL flask, and add an equal volume of aniline. Reflux for 1 hour, swirling the flask occasionally. Allow to cool, and pour 60 mL of alcohol through the condenser into the flask. Remove the flask from the condenser, add 1 g of charcoal, and stir. Filter the slurry into a 250-mL beaker. Add water dropwise until a few crystals form or the solution becomes slightly cloudy.
[NOTE—If too much water is added, an oil will form. Add alcohol dropwise until the oil dissolves.
] Allow the mixture to stand or refrigerate until crystals are formed. Collect the crystals on a filter paper inserted in a 45-mm porous glass filter funnel. Wash the crystals with 75 mL of 25% alcohol: the crystals have a clean, white, glossy appearance. If not, recrystallize by dissolving the crystals in about 50 mL of alcohol. Add about 1 g of charcoal, stir, filter into a 150-mL beaker, and continue as directed above, beginning with “Add water dropwise.” Dry the crystals in vacuum at 50
for 2 hours: the crystals so obtained melt between 66
and 67.5
, the procedure for
Class Ia being used (see
Melting Range or Temperature 
741
).
[NOTE—If the melting point is low, additional drying or recrystallization may be necessary.
]
;)
