2/ in naphthalene

The advantages offered by Eq. (5) can be demonstrated by an example. Suppose we want to know the orbital energies of a system which arises upon replacing the carbon 2pz orbital in position 2 in naphthalene by a 2pz orbital of a heteroatom, X. Substituting the... 

There are four nonequivalent types of C—C bonds in naphthalene, these being represented by C,—C2, C2—C3, C4—C10, and Q—C,(). By using the MO expressions in Table 7.2, the n bond order of each type may be computed. As before, in treating tetramethylenecyclobutane, the bond order, pmtn of the bond between atoms m and n is defined as the sum of contributions from each occupied MO, each contribution being given by twice (for two electrons) the product of the coefficients of 0OT and 0 in that MO. For p,2 in naphthalene we have... 

Thus in butadiene the central bond belongs to class 2, in benzene all are of class 2, in naphthalene the division is as indicated. 

Much of our knowledge of the frequency dependence of VER rates in polyatomic molecules stems from low-temperature studies of molecular crystals [2] such as pentacene (PTC 221 4) guest molecules in a crystalline naphthalene (N C,., H ) host. In naphthalene, the phonon cut-off frequency is -180 cm [97]. At low temperature,... 

The cross-conjugated system of two a,P-unsaturated carbonyl groups of both 1,2- and 1,4-quinones occurs in many polynuclear hydrocarbons, eg, 1,2-naphthoquinone [524-42-5] (8) and 1,4-naphthalenedione [130-15-4] (1,4-naphthoquinone) (9) (see Fig. 1). The carbonyl groups may be located in different rings, but occupy positions corresponding to the 1,2- or 1,4-orientation of monocyclic quinones, eg, in naphthalenes such as 2,6-naphthoquinone... 

The other important carbocycHc ring system used in dyes is naphthalene [91-20-3]. Here the preferred position of attack is the 1-position. However, 2-substituted naphthalenes are thermodynamically more stable, and under equiUbratiag conditions the 2-isomer is formed ia preference to the 1-isomer. 

Having its pyrazolic 4-position substituted, electrophilic attack on indazoles takes place in the 3-position and in the homocycle (the 5- and 7-positions). The condensation of a benzene ring results in a decrease of the aromaticity of the pyrazole moiety, as in naphthalene compared to benzene, and therefore basic ring cleavage is easier in indazoles than in pyrazoles (Section 4.04.2.1.7(v)). 

Bromomethyl)-naphthalene [939-26-4] M 221.1, m 52-54°, 56°, 56-57°, b 133-136°/0.8mm, 214°/100mm. Dissolve in toluene, wash with saturated aqueous NaHC03, dry (Mg SO4), evaporate and fractionally distil the residue and recrystallise the distillate from EtOH. [J Chem Soc 5044, 1952 Bull Soc Chim Fr 566 7955.]... 

Enzymatic oxidation of naphthalene by bacteria proceeds by way of the intermediate ciy-diol shown. Which prochiral faces of C-1 and C-2 of naphthalene are hydroxylated in this process ... 

The NMR spectrum of this compound shows a diamagnetic ring current of the type expected in an aromatic system. X-ray crystal structures of 1 and its carboxylic acid derivative 2 are shown in Fig. 9.2. Both reveal a pattern of bond lengths very similar to that in naphthalene (see p. 534). ... 

Two sites are available for substitution in naphthalene, C-1 and C-2, C-1 being normally the prefened site of electrophilic attack. 

The benzo-annellated derivative naphtho[l,2-c]furoxan is numbered according to the system (2)] shown. In the literature the name 1,2-naphthofuroxan may often be found, with the same numbering as for a 1,2-disubstituted naphthalene. Although the latter method is perhaps a little clearer to follow, the more systematic scheme (2) will be adhered to in this chapter. 

Interest in this reaction was revived when the relevance of a carbene mechanism was realized, particularly following the demonstration (cf. SectionI,B) of a similar ring expansion of indene to 2-chloro-naphthalene by dichlorocarbene via the cyclopropane adduct. Indeed, at this time Nakazaki suggested that these reactions occurred by the addition of dichlorocarbene to the indolyl anion and subsequent rearrangement to the indolenine and, with loss of chloride ion, to the quinoline [Eq. (12)]. The preference of dichlorocarbene for... 

To derive the maximum amount of information about intranuclear and intemuclear activation for nucleophilic substitution of bicyclo-aromatics, the kinetic studies on quinolines and isoquinolines are related herein to those on halo-1- and -2-nitro-naphthalenes, and data on polyazanaphthalenes are compared with those on poly-nitronaphthalenes. The reactivity rules thereby deduced are based on such limited data, however, that they should be regarded as tentative and subject to confirmation or modification on the basis of further experimental study. In many cases, only a single reaction has been investigated. From the data in Tables IX to XVI, one can derive certain conclusions about the effects of the nucleophile, leaving group, other substituents, solvent, and comparison temperature, all of which are summarized at the end of this section. 

The rate of amination and of alkoxylation increases 1.5-3-fold for a 10° rise in the temperature of reaction for naphthalenes (Table X, lines 1, 2, 7 and 8), quinolines, isoquinolines, l-halo-2-nitro-naphthalenes, and diazanaphthalenes. The relation of reactivity can vary or be reversed, depending on the temperature at which rates are mathematically or experimentally compared (cf. naphthalene discussion above and Section III,A, 1). For example, the rate ratio of piperidination of 4-chloroquinazoline to that of 1-chloroisoquino-line varies 100-fold over a relatively small temperature range 10 at 20°, and 10 at 100°. The ratio of rates of ethoxylation of 2-chloro-pyridine and 3-chloroisoquinoline is 9 at 140° and 180 at 20°. Comparison of 2-chloro-with 4-chloro-quinoline gives a ratio of 2.1 at 90° and 0.97 at 20° the ratio for 4-chloro-quinoline and -cinnoline is 3200 at 60° and 7300 at 20° and piperidination of 2-chloroquinoline vs. 1-chloroisoquinoline has a rate ratio of 1.0 at 110° and 1.7 at 20°. The change in the rate ratio with temperature will depend on the difference in the heats of activation of the two reactions (Section III,A,1). 

Condensation of the dianion of 1,2-dimercaptobenzene (380) with 1-chloro-8-nitronaphthalene (483) in DMF provided 45% of benzo[2,3]naphthalene [5,6,7-/j][l,4]dithiepin (484) and a small amount of its 5-oxide 485 (Eq. 44) (89JHC667). Though the structure of 485 was adequately determined (NMR studies, X-ray crystallography), its formation was not definitely explained. 

Methylisoquinolinium 2-carboxylate (230), originally prepared by Quast (70LA64), was recently identified as a defensive betaine from Photuris versicolor fireflies (99JNP378). It is a pseudo-cross-conjugated mesomeric betaine isoconjugate to the odd alternant hydrocarbon 2-isopropenyl-naphthalene anion which is an odd alternant hydrocarbon anion. This compound therefore is a member of class 13, which is very rare. The UV absorption maxima Imax (methanol) were found at 235 (4.35), 320 (shoulder, 3.97), and 326 (3.99) nm. This compound undergoes similar reactions as Homarine 19 (Scheme 75). The NMR data are presented in Table VIII. 

Methoxy-Naphthalene (Me thy 1-0-naphthyl-ether). Cryst, mp 13—14°, bp 274°. Sol in eth, chlf benz. Prepn from K-0-napthalate by heating with methyl chloride at 300°... 

CO 2 —220.52%, cryst from petr ether plus benz or from ale, mp 120—23° (decompn). Sol in ale petr eth plus benz. Prepn from an AcOH soln of 2-methoxy-naphthalene reacted with a HC1 satd suspension of paraformal dehyde in AcOH Ref Beil 6, 3020 ... 

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