Solubility of Alcohols in Water

The solubility of alcohols in water gradually decreases as the hydrocarbon portion of the molecule lengthens. 

There is a gradation in the solubility of alcohols in water. The lower alcohols (methanol, ethanol and propan-l-ol) are miscible with water because they can hydrogen bond with water molecules. Heptan-l-ol and longer chain alcohols are insoluble in water. So, as the chain length increases, the solubility decreases because the long non-polar hydrocarbon part of the molecule masks the polar hydroxyl group. 

Alcohols with three or fewer carbons atoms are miscible in water in all proportions. The solubility of alcohols in water decreases with increasing number of carbon atoms, so that alcohols with more than six carbon atoms are nearly insoluble. As the number of carbon atoms increases, the solubility in nonpolar solvents increases. 

Solubilities, of alcohols in water, 1046 of stereoisomers in water and in alcohol, 1047... 

The oldest publication on structure-activity relationships (SARs) known to us from the literature is a paper by Cros from 1861. He compared the toxic effect of alcohols in various species after different routes of administration. He found an increase in toxic effect with decreasing water solubility, that is increasing lipophilicity. Cros was also the first to detect a maximum in activity followed by a decrease, i.e. a non-linear relationship, as a function of solubility of alcohols in water. 

Kinoshita, K., Ishikawa, H., Shinoda, K. (1958) Solubility of alcohols in water determined by the surface tension measurements. Bull. Chem. Soc. Japan 31, 1081-1082. 

Refer to Table 27-8, and explain the trends in boiling points and solubilities of alcohols in water. 

Fig. 2 Solubility of alcohols in water calculated from Henry s law. (View this art in color at www.dekker.com.)...

Low-molecular weight alcohols are soluble in water. The hydrogen bond formation plays a key role in the solubility of alcohols in water. In other words, hydrogen bonds enhance the solubility of alcohols in H O. As the number of carbons increases, the solubility of alcohols decreases as they become more and more similar to hydrocarbons with longer and longer nonpolar hydrocarbon chains. 

Methanol, ethanol, both propyl alcohols, and rerr-butyl alcohol are completely miscible with water (Table 11.1). The solubility of alcohols in water gradually decreases as the hydrocarbon portion of the molecule lengthens long-chain alcohols are more alkanelike and are, therefore, less like water. 

Describe the classification of alcohols describe the solubility of alcohols in water. 

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