Melting point of naphthalene

Terminal olefins appear to be reactive only if they are not allylic in nature (e.g., styrene and 2,4,4-trimethyl-l-pentene). Allylbenzene (3-phenyl-l-pro-pene) is inert toward nitrosyl chloride, whereas propenylbenzene (1-phenyl-l-propene) reacts. The preparations are usually carried out at low temperatures. When molecular weights of the products are determined at 5°C, they correspond to dimeric structures. At the melting point of naphthalene, the products are predominantly monomeric. This observation is reasonably general for nitroso compounds [69]. 

In general, naphthalene reacts much more easily than benzene, and nitration of naphthalene takes place so energetically that polynitro compounds are formed easily. On the other hand, since the reaction is carried out at a temperature below the melting point of naphthalene, the larger particles may not be attacked by the nitric acid under the... 

Once the experimental work has been completed you then need to consider how to interpret the results, i.e. how to maximize the chemical information inherent in the data. Initial attempts are often centred around plotting the data, to visualize trends and to allow conclusions to be drawn. The simplest form of data visualization is simply to tabulate the results (Chapter 38). As an example, if a class of students has determined the melting point of naphthalene, it is a relatively simple matter to tabulate the data (see Table 43.1). One possibility for the data is then to calculate the mean and standard deviation. Another approach would be to plot the data as a histogram, as in Fig. 43.1, so we are then able to make a visual interpretation of the quality of this univariate (one-variable) data. 

Fig, 14. Effect of addition of biphenyl on the melting point of naphthalene... 

Problem The melting point of naphthalene is 80.2° C, and its molar heat of fusion at this temperature is 4,540 cal. mole . Determine its ideal solubility at 20° C. 

The melting point of naphthalene is lowered 6.85°C per mole of solute in 1000. g of solvent. Perform the calculations in TABLE 20.5 including the sample calculations on the back of TABLE 20.5. 

Polycyclic aromatic compounds have significantly higher melting points than other hydrocarbons of similar size. TTie melting point of naphthalene is much higher than that of cyclodecane, and anthracene s is much higher than cyclotetradecane s. 

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