91-57-6 2-Methylnaphthalene

Polynuclear Aromatics. The alkylation of polynuclear aromatics with olefins and olefin-producing reagents is effected by acid catalysts. The alkylated products are more compHcated than are those produced by the alkylation of benzene because polynuclear aromatics have more than one position for substitution. For instance, the alkylation of naphthalene [91-20-3] with methanol over mordenite and Y-type zeoHtes at 400—450°C produces 1-methylnaphthalene [90-12-0] and 2-methylnaphthalene at a 2-/1- ratio of about 1.8. The selectivity to 2-methylnaphthalene [91-57-6] is increased by applying a ZSM-5 catalyst to give a 2-/1- ratio of about 8 (102). 

Methylnaphthalene [91-57-6] M 142.2, m 34.7-34.9 , b 129-130 /25mm. Fractionally crystd repeatedly from its melt, then fractionally distd under reduced pressure. Crystd from benzene and dried under vacuum in an Abderhalden pistol. Purified via its picrate (m 114-115°) as described for 1-methylnaphthalene. 

Figure 14.19 Typical GC chromatogram of the separated di-aromatics fraction of a middle distillate sample Peak identification is as follows 1, naphthalene 2, 2-methylnaphthalene 3, 1-methylnaphthalene 4, biphenyl 5, C2-naphthalenes 6, C3-naphthalenes 7, C4-naph-thalenes 8, C5+-naphthalenes 9, benzothiophene 10, methylbenzothiophenes 11, C2-ben-zotliiopIrenes. Note the clean baseline between naphthalene and the methylnaphthalenes, which means that no overlap with the previous (mono-aromatics) fraction has occuned.

Figure 15.9 Use of heart-cutting for the identification of target compounds in 90% evaporated gasoline. Peak identification is as follows 1, 1,2,4,5-teti amethylbenzene 2, 1,2,3,5-teti amethylbenzene 3, 4-methylindane 4, 2-methylnaphthalene 5, 5-methylindane 6, 1-methylnaphthalene 7, dodecane 8, naphthalene 9,1,3-dimethylnaphthalene. Adapted from Chromatography, 39, A. Jayatilaka and C.F. Poole, Identification of petroleum distillates from fire debris using multidimensional gas chromatography , pp. 200-209, 1994, with permission from Vieweg Publishing.

Dinitro-1 -Methylnaphthalene, mp 14.2—43°, needles from ale. Prepn from 5-nitro-1-methyl-naphthalene by nitration on a steam bath using nitric (d 1.52g/cc) coned sulfuric acids in glac AcOH Acj O... 

X-Dinitro-1-Methylnaphthalene, mp 176°, brown plates from AcOH. Prepn from 4-nitro-1-methylnaphthalene by nitration in the cold with nitric acid (d 1.5g/cc)... 

X.X-Dinitro-1 -Methylnaphthalene, mp 168°, needles from benz. Prepn from 1-Methylnaphthalene by nitration with fuming nitric acid at 0° Ref Beil 5, 1627 ... 

Salts of diazonium ions with certain arenesulfonate ions also have a relatively high stability in the solid state. They are also used for inhibiting the decomposition of diazonium ions in solution. The most recent experimental data (Roller and Zollinger, 1970 Kampar et al., 1977) point to the formation of molecular complexes of the diazonium ions with the arenesulfonates rather than to diazosulfonates (ArN2 —0S02Ar ) as previously thought. For a diazonium ion in acetic acid/water (4 1) solutions of naphthalene derivatives, the complex equilibrium constants are found to increase in the order naphthalene < 1-methylnaphthalene < naphthalene-1-sulfonic acid < 1-naphthylmethanesulfonic acid. The sequence reflects the combined effects of the electron donor properties of these compounds and the Coulomb attraction between the diazonium cation and the sulfonate anions (where present). Arenediazonium salt solutions are also stabilized by crown ethers (see Sec. 11.2). 

Complexation with polyaromatic systems has also been observed. For instance, Mlnaphthalenelj, M = Cr (88,183), Mo (183), V (183), or Ti (183) may be synthesized in a solution reactor with the appropriate, metal vapors at liquid-nitrogen temperature. The Cr/naphthalene complex is less stable (dec. 160°C) than CrtCsH ) (m.p. 283-284° C). In fact, the naphthalene ligand is sufficiently labile to allow reaction under mild conditions, to afford CrL (L = CO or Bu NC), or Cr(naphth)Ls [L = PFj, P(OMe)3, or PMea]. The Mo, V, and Ti species are equally reactive. Analogous 1-methylnaphthalene complexes were also isolated (183). In addition, the complexes shown in Fig. 38 were synthesized by reaction, at the temperature of liquid nitrogen, of Cr atoms with 1,4-diphenylbutane (35, 201, 202). Analogous complexes were formed with 1,5-diphenylbutane (202). 

Miscellaneous. Symmetrical olefins were obtained from reactive ylides and sulphur under fairly vigorous conditions. Yields were high when R = Ar, but the ethylidenephosphorane gave only 28% of hex-3-ene at 150 ""C in 1-methylnaphthalene. 

C11H10 C11H10 C11H1402 C11H22 C11H22 C11H24 1- METHYLNAPHTHALENE 2- METHYLNAPHTHALENE BUTYL BENZOATE N-HEXYLCYCLOPENTANE 1-UNDECENE N-UNDECANE... 

Laser flash photolysis techniques offer the possibility of examining in detail the transient processes responsible for the photostabilizing effect discussed above. The triplet lifetimes are frequently too short, even for this technique however, they can still be estimated using as a probe the quenching by 1-methyl-naphthalene, which leads to the formation of its easily detectable triplet. The optical absorbance due to the 1-methylnaphthalene triplet (Aft) produced as a result of energy transfer is related to the Stern-Volmer slope by equation 5, where N stands for... 

Figure 1. Plot according to Equation 5 for CoPT(l). Triplet 1 -methylnaphthalene was monitored at 420 nm.

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