Chloroethane physical properties

Alcohols and phenols are quite different from the hydrocarbons and alkyl halides we ve studied thus far. Not only is their chemistry much richer, their physical properties are different as well. Figure 17.1, which provides a comparison of the boiling points of some simple alcohols, alkanes, and chloroalkanes, shows that alcohols have much higher boiling points. For example, 1-propanol (MW = 60), butane (MW - 58), and chloroethane (MW = 65) have similar molecular weights, yet 1-propanol boils at 97"C, compared to 0.5°C tor the alkane and 12.5°C for the chloroalkane. 

The term S) represents the absolute configuration seen in 8 and the term R) represents the absolute configuration seen in 9. Which structure is ( ) -1-bromo-l-chloroethane, 8 or 9 Given only the name, it is impossible to know The names R) and (S) are determined by an arbitrary (but universally accepted) set of rules. The (+) or (-) label is the specific rotation, a physical property. Therefore, if only the names R or S) are given, that information does not allow one to correlate the structure with the sign of the specific rotation. It is necessary to identify 8, isolate it, put it into a polarimeter, and then determine its specific rotation. Alternatively, the same can be done for 9. Only after the physical measurement of each named compound can specific rotation of an enantiomer be correlated with the absolute configuration of that enantiomer. This is a very important lesson for this chapter. 

The physical properties of alcohols are quite different from the physical properties of alkanes or alkyl hahdes. For example, compare the boiUng points for ethane, chloroethane, and ethanol. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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