Physical properties of alkynes

The physical properties of alkynes closely resemble those of alkanes and alkenes already described in sections 15.1.4 and 15.2.3: alkynes are less dense than water, insoluble in water, and reasonably soluble in less-polar organic solvents such as ether, benzene and carbon tetrachloride. As shown in Table 15.5, both the melting point and the boiling point of alkynes rise steadily with increasing molecular mass -- ethyne (198 K) and propyne (250 K) are gases at room temperature, but by the time the chain reaches pent-1-yne (313 K) and hex-1-yn …