Benzene derivatives table

The IR spectra of (1) and its derivatives show a well-defined aromatic system, evidenced by the correlation of the C—C and C—H stretching frequencies of (1) and its 4- and 5-substituted derivatives (Me, Cl and Br) with the corresponding frequencies for benzene derivatives (Table 13) (69CHE180, 69KGS235). 

TABLE 9.3 The nitration of benzene derivatives containing positively charged substituents ... 

Table 7.9 Electronic Absorption Bands for Representative Chromophores Table 7.10 Ultraviolet Cutoffs of Spectrograde Solvents Table 7.11 Absorption Wavelength of Dienes Table 7.12 Absorption Wavelength of Enones and Dienones Table 7.13 Solvent Correction for Ultraviolet-Visible Spectroscopy Table 7.14 Primary Bands of Substituted Benzene and Heteroaromatics Table 7.15 Wavelength Calculation of the Principal Band of Substituted Benzene Derivatives...

TABLE 7.15 Wavelength Calculation of the Principal Band of Substituted Benzene Derivatives In ethanol. 

U.S. petroleum benzene prices since 1974 are Hsted in Table 6 (64). Until 1978, benzene prices were relatively stable and through 1985 they increased considerably, peaking in 1981 because of the increased demand for aromatics in the gasoline pool. At that time, there was also a large surplus of low priced imported benzene and a softening of the ethylbenzene—styrene market. The decline of cmde oil prices in 1986 caused a dramatic drop in domestic benzene prices. In 1987, U.S. benzene production increased 13.9% over 1986, and this rise was largely ascribed to a favorable export market for benzene derivatives... 

Acetophenone is one of the commonly encountered benzene derivatives listed in Table 11.1. 

Phenol and anisole are among the commonly encountered benzene derivatives listed in Table 11.1. Electrophilic aromatic substitution in phenol is discussed in more detail in Section 24.8. 

It should be pointed out that the existence of stable structures of the intermediate-complex type (also known as a-complexes or Wheland complexes) is not of itself evidence for their being obligate intermediates in aromatic nucleophilic substitution. The lack of an element effect is suggested, but not established as in benzene derivatives (see Sections I,D,2 and II, D). The activated order of halogen reactivity F > Cl Br I has been observed in quantita-tivei36a,i37 Tables II, VII-XIII) and in many qualitative studies (see Section II, D). The reverse sequence applies to some less-activated compounds such as 3-halopyridines, but not in general.Bimolecular kinetics has been established by Chapman and others (Sections III, A and IV, A) for various reactions. 

The reactivities of 4- and 2-halo-l-nitronaphthalenes can usefully be compared with the behavior of azine analogs to aid in delineating any specific effects of the naphthalene 7r-electron system on nucleophilic substitution. With hydroxide ion (75°) as nucleophile (Table XII, lines 1 and 8), the 4-chloro compound reacts four times as fast as the 2-isomer, which has the higher and, with ethoxide ion (65°) (Table XII, lines 2 and 11), it reacts about 10 times as fast. With piperidine (Table XII, lines 5 and 17) the reactivity relation at 80° is reversed, the 2-bromo derivative reacts about 10 times as rapidly as the 4-isomer, presumably due to hydrogen bonding or to electrostatic attraction in the transition state, as postulated for benzene derivatives. 4-Chloro-l-nitronaphthalene reacts 6 times as fast with methanolic methoxide (60°) as does 4-chloroquinoline due to a considerably higher entropy of activation and in spite of a higher Ea (by 2 kcal). ... 

In conditions of base catalysis, the acetylenylpyrazolecarboxylic acid hydrazides, as opposed to benzene derivatives, are more difficult to cyclize compared with the benzoic acid derivatives and are isomerized only after heating in alcohol in the presence of KOH, forming not five- but six-membered lactams. The yields of pyri-dopyrazoles were 80-90% (Scheme 133 Table XXVIII) (85IZV1367 85MI2). 

Table 18-IV shows the structures of a few simple benzene derivatives that are important commercial products. Study these structures so that you can see their relationship with the simple compounds from which they are derived.

Benzene-1,2-diamine or derivatives are generally employed as the diamino component in ring-closure reactions with 1,2-dicarboxylic acids or derivatives (Table 2). 

The effect of the diazonio group on the reactivity of benzene derivatives was studied quantitatively by Lewis and Johnson (1959) by measuring the acidity constants of 3- and 4-diazoniobenzoic acid, of the 4-diazonio-anilinium ion, of 3- and 4-diazo-niophenol, and of 4-diazoniophenylacetic acid. The results are given in Table 7-3. 

NATURE OF THE Table VI. CHEMICAL Benzene derivatives. BOND. VI 615... 

Substituent effects of the benzene ring in the alkylation of benzene derivatives with I were studied by comparison with benzene it.self. These results are summarized in Table HI. 

In the alkylation of benzene with (dichloroalkyl)chlorosilanes in the presence of aluminum chloride catalyst, the reactivity of (dichloroalkyl)silanes increases as the spacer length between the C—Cl and silicon and as the number of chloro-groups on the silicon of (dichloroalkyl)chlorosilanes decreases as similarly observed in the alkylation with (cD-chloroalkyl)silanes. The alkylation of benzene derivatives with other (dichloroalkyl)chlorosilanes in the presence of aluminum chloride gave the corresponding diphenylated products in moderate yields.Those synthetic data are summarized in Table XI. 

Comparison (Tables 7-9) shows that 47 and 48 are similar in their host properties, but they are not equivalent in hehavior. Thus, host compound 48 is more qualified to select according to spatial aspects (see benzene derivatives) and, as a rule, it also forms the thermally more stable inclusions. This may be attributed to the rigid molecular geometry of the spirane 48, whereas the biaryl 47 allows sterical adaptation to different guests via the flexible hinge to a certain degree. 

The zirconacyclopentadiene prepared from unsymmetrical trimethylsilylpropyne and diphenylacetylene reacts with DMAD in the presence of 2 equivalents of CuCl and 3 equivalents of DMPU to give the corresponding benzene derivative 72c in 56% yield as a single product in a one-pot reaction. Some other examples are shown in Table 2.3. 

In this context see also Refs. [83a, 83b]. Comninellis and Plattner [287,287a, 288] have developed a simple method for estimating the facility of the electrochemical oxidation of organic species based on a newly defined electrochemical oxidizability index (EOI) and the degree of oxidation using the electrochemical oxygen demand (EOD). Electrochemical oxidizability index for various benzene derivatives obtained at Pt/Ti and Sn02-ABB-anodes are listed in Table 23. 

Taking into account the limitations discussed in the preceding section, the constants determined by various methods for a series of homologous compounds may be compared with one another and, if related to a reference substance, may be represented in the form of a basicity scale. In general, p-xylene has been chosen as the reference substance within the series of benzene derivatives (Andrews, 1964). In Table 15 benzene is taken as equal to 1, since this aromatic substance has been measured... 

Table 15 summarizes the values obtained for all methylbenzenes by various methods. Asr has already been repeatedly mentioned, the basicity increases with the number of methyl groups. The differing increase in basicity obtained by different methods is particularly clear if one compares the values for hexamethylbenzene, which vary between 4 and 140. The best agreement between the various methods is found for the first members of this series, including the trimethyl-substituted benzene derivatives. 

A large number of papers has been devoted to the influence of substituents upon the reactivity of benzene nucleus. Extensive studies concerning various benzene derivatives and catalysts from the platinum group metals have been published by H. A. Smith and his co-workers (for a summary see 36). The most consistent sets of data on alkylbenzenes are available from him and other groups of authors. Table VI summarizes the influence of the structure of a single alkyl group Table VII (94, 95, 97-103) summarizes the influence of the number and position of the methyl groups. Both series show very similar behavior on all metal catalysts, a decrease in rate with the size... 

The effects of ring constituents in the alkylation of benzene derivatives (Ph-R) with la are summarized in Table I. 

Benzene derivatives exhibit medium to strong absorption in the UV region. Bands usually have characteristic fine structure and the intensity of the absorption is strongly influenced by substituents. Examples listed in Table 2.3 include weak auxochromes (-CH3, -Cl, -OCH3), groups which increase conjugation (-CH=CH2, -C(=0)-R, -NOj) and auxochromes whose absorption is pH dependent (-NH2 and -OH). 

Table 2.3 UV Absorption Bands in Common Benzene Derivatives...

Table 5.6 gives characteristic chemical shifts for the aromatic protons in benzene derivatives. To a first approximation, the shifts induced by substituents are additive. So, for example, an aromatic proton which has a -NO2 group in the para position and a -Br group in the ortho position will appear at approximately 7.82 ppm [(7.26 + 0.38(p-NO2) + 0.18(o-Br)]. 

---