ALIPHATIC ALCOHOLS
REACTIONS AND CHARACTERIZATION OF
ALIPHATIC ALCOHOLS
Carry out the following simple experiments ; these have been selected to illustrate some of the general properties of alcohols.
(i) Miscibility with water. Measure out 3-1 ml. (2-5 g.) of n-butyl alcohol into a dry 100 ml. conical or flat-bottomed flask provided with a well-fitting stopper. From a burette add distilled water to the alcohol, a few drops at a time and shake vigorously after each addition, until a slight but permanent turbidity is produced. Note the volume of water added and calculate the solubility of water in n-butyl alcohol at the temperature of the laboratory. Continue the addition of water, 2-3 ml. at a time and with vigorous shaking, until the contents of the flask are just homogeneous : near the point of homogeneity the additions should be reduced to portions of 1 ml. Note the total volume of water which has been added from the burette, and calculate the solubility of n-butanol
in water at the temperature of the laboratory.
The student will doubtless be aware of the fact that methyl, ethyl, n-propyl and tso-propyl alcohols are completely miscible with water. The solubilities of the higher alcohols decrease progressively as the carbon content increases. The solubilities of all types of alcohols with five carbon atoms or more are quite smal miscible.
Divide the saturated solution of n-butyl alcohol in water into three approximately equal parts. Treat these respectively with about 2*5 g. of sodium chloride, potassium carbonate and sodium hydroxide, and shake each until the solids have dissolved. Observe the effect of these compounds upon the solubility of n-butanol in water. These results illustrate the phenomenon of salting out of organic compounds, i.e., the decrease of solubility of organic compounds in water when the solution is saturated with an inorganic compound. The alcohol layer which separates is actually a saturated solution of water in n-butyl alcohol.