Physical Properties of Benzene and Its Derivatives

The melting points, boiling points, and densities of benzene and some derivatives are given in Table 16-1. Benzene derivatives tend to be more symmetrical than similar aliphatic compounds, so they pack better into crystals and have higher melting points. For example, benzene melts at 6°C, while hexane melts at —95°C. Similarly, para-disubstituted benzenes are more symmetrical than the ortho and meta isomers, and they pack better into crystals and have higher melting points. 

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Physical Properties of Benzene and Its Derivatives 742 16-15 Spectroscopy of Aromatic Compounds 743 EssentialTerms 746 Study Problems 748... 

The physical properties of benzene and its derivatives are quite similar to those of other hydrocarbons. The compounds are nonpolar, insoluble in polar solvents such as water, but generally soluble in nonpolar solvents. In fact, derivatives of benzene are widely used as the solvent for many nonpolar organic compounds. Like other hydrocarbons of comparable molar mass, benzene is a liquid at room temperature. 

Giovanni Speroni s scientific interests ranged from synthetic organic chemistry to physical properties of organic compounds, to consideration of important structural information obtainable from these studies. These latter studies were so well-known that Speroni was commissioned to write the chapter on Physical and Chemical Properties of Isoxazole and its Derivatives in the review on isoxazole chemistry edited by Adolfo Quilico [6]. This chapter collected various properties of isoxazole and its derivatives density, surface tension, water solubility at various temperatures. Data from these measurements indicated augmented self-association in compounds with the 3-position free. Extensive research was directed to determining the dipole moments of isoxazoles in benzene and, for comparison, in dioxane. Speroni invented and constructed the device to measure dielectric constants, from which the dipole moments of organic substances were obtained. 

THTOPHENE. [CAS 110-02-1]. (CH C.H)2)S, formula weight 84.H, colorless liquid resembling benzene in odor, mp —30°C, bp 84°C. sp gr 1,070. Thiophene and its derivatives closely resemble benzene and its derivatives in physical ancl chemical properties. Thiophene is present in coal tar and is recovered in the benzene distillation fraction (up to about 0.5% of the benzene present). Its removal from benzene is accomplished by mixing with concentrated sulfuric acid, soluble thiophene sulfonic acid being formed. Thiophene gives a characteristic blue coloration with isatin in concentrated sulfuric add. 

Since 1987 many new synthesis methods have appeared in the literature, designed to obtain improved PPP. The physical and electrochemical properties of PPP are now better understood, in particular for PPP synthesized by electrooxidation of benzene or its derivatives [5]. 

In general, pyridazine can be compared with pyridine. It is completely miscible with water and alcohols, as the lone electron pairs on nitrogen atoms are involved in formation of hydrogen bonds with hydroxylic solvents, benzene and ether. Pyridazine is insoluble in ligroin and cyclohexane. The solubility of pyridazine derivatives containing OH, SH and NH2 groups decreases, while alkyl groups increase the solubility. Table 1 lists some physical properties of pyridazine. 

Thiophene was found in tar, gas and industrial benzene obtained from coal in the nineteenth century. A large number of thiophene derivatives are described in the literature and their physical properties, nucleophilic substitution and biological activity are still of current interest [ ] As for polymers, thiophene was oxidized by such acidic materials as orthophosphoric acid or a synthetic silica-alumina catalyst to yield liquid oligomer which consisted of its trimer containing a small amount of its pentamer. A report on this was published as early as 1883 [2], However, modem studies on polythiophene, aiming at the preparation of electrically conductive polymers, started at the beginning of the 1980s [3-5]. 

The separations listed in Table HI result from a combination of differences in solubility and diffusivity. A difference in physical solubility of benzene derivatives would be expected and is observed. In general, as the substituted side chain on benzene becomes longer its solubility in water is reduced due to its more organic nature. Therefore, if the separation was based solely on the differences in solubility, the order of decreasing flux values would be benzene > toluene > ethylbenzene > cumene. A difference in diffusion coefficients of the benzene derivatives would also be expected. In general, diffusion coefficients decrease as molecular size increases. Therefore, the order of decreasing diffusivity would be benzene > toluene > ethylbenzene > cumene. Both physical properties predict the trends seen for Na+-Nafion membranes. While incorporation of Ag+ ions into the... 

Elemental composition Fe 30.02%, C 64.56%, H 5.42%. An alcohohc or benzene solution of the compound may be analyzed by GC/MS. Additionally, the cyclopentadienyl hgand may be identified from the IR (303 cm-i) and nmr spectra and x-ray crystallographic analysis. Furthermore, the compound may be derivatized with an electrophile (See Reactions) and the derivative formed may be identified by its physical and chemical properties and elemental composition. 

Abstract. A comparative investigation of C6o fiillerene solubility and donor force of alkyl derivatives of benzene has been performed. Based on the found correlation, which was determined by current methods, between C6o solubility and donor force of solvents, it has been concluded that the process of Cgo dissolution in aromatic hydrocarbons is a process of intermolecular interaction combined with charge-transfer and formation of complexes of the donor-acceptor type. The agreement between a series of physical and chemical phenomena (factors, properties) observed in studies of C60 solubility and a number of existing criteria which allow the phenomena to be interpreted as a manifestation of the charge-transfer interaction substantiates our conclusion. 

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