Methylnaphthalene isomers

There are fewer UV absorbance studies of dinaphthylalkanes. Chandross and Dempster 9) have studied l,2-bis(l-naphthyl)ethane, l,3-bis(l-naphthyl)propane and l,4-bis(l-naphthyl)butane, as well as l,3-bis(2-naphthyl)propane and the compound l-(l-naphthyl)-3(2-naphthyl)propane. The latter had the same absorbance spectrum as a 50/50 mixture of 1- and 2-methylnaphthalene, while the bis compounds were shown to have the same absorbance spectrum as the corresponding methylnaphthalene isomer. These studies were made in a 90/10 v/v mixture of methylcyclohexane/isopen-... 

The volume change AV associated with intermolecular excimer formation has been determined for naphthalene and various alkyl derivatives through the application of pressure 74). For naphthalene and the two methylnaphthalene isomers, the value of AV = — 16cm3/mole was measured at room temperature. Assuming the sandwich structure for the excimer, and taking the projected area of the naphthalene molecule... 

Electric shaver 1 -ethoxy-2-propanol,cyclohexanone, 2 toluene, naphthalene, methylnaphthalenes (isomers), cyclohexanone, C3-/C4-benzenes, aliphatic hydrocarbons, BHT... 

We, at Sun Oil Co., are greatly interested in separating 2,6-dimethyl-naphthalene from 2,7-dimethyInaphthalene (2,7-DMN). These 2 di-methylnaphthalene isomers are too close-boiling (262.0°C for 2,6-DMN and 262.3°C for 2,7-DMN) to allow separation via fractional distillation. Furthermore, both isomers are solid at room temperature (mp 111°-112°C for 2,6-DMN and 96°-97°C for 2,7-DMN). Only a small fraction of the naturally-occurring 2,6-DMN in a refinery stream can be crystallized before a binary eutectic containing 42% 2,6-DMN and 58% 2,7-DMN begins to precipitate. 

After CLD modification, the zeolites exhibit excellent shape selectivity for separation and purification of various isomers. For instance, the pore-size-adjusted NaY zeolite after Si(OCH3)4 modification is very effective for the separation of methylnaphthalene and trimethylbenzene isomers. Because the pore size of NaY itself is large, before modification the zeolite shows no shape selectivity for the two methylnaphthalene isomers, and the adsorption capacities for 1-methylnaphthalene and 2-methylnaphthalene are similar. However, as the pore size decreases, the zeolite exhibits increasing adsorption capacity... 

Both methylnaphthalene isomers are present in coal tar, at levels of 0.7% (1-methylnaphthalene) and 1.5% (2-methylnaphthalene). 

Methylnaphthalenes are also found in petroleum-derived feedstocks, such as pyrolysis tar from ethylene production and cat-cracker residues (see Chapter 9.2.2). The l-/2-methylnaphthalene isomer ratio, which is around 1 2.5 for methyl-naphthalenes in coal tar, is higher in this case, because of the lower temperature exposition of the raw material, and is close to 1 1. Recovery of methylnaphthalenes from these sources is generally only carried out on a small scale, since it can be extremely intricate to separate co-boiling compounds petroleum-derived methylnaphthalenes has served as a feedstock for naphthalene production by dealkylation, especially in the USA in the 1960 s and 70 s. 

Mass 142—Use to quantitate the two methylnaphthalene isomers from their corresponding calibration curves. Ignore all other mass 142 peaks. 

In practice, the reference base is usually taken not as a-methylnaphthalene but as heptamethyinonane (HMN), a branched isomer of n-cetane. The HMN has a cetane number of 15. In a binary system containing Y% of n-cetane, the cetane number CN vyOl be, by definition (./ - V ... 

Because a-copaene is a sesquiterpene, a hydrocarbon, and because of very early reports that kerosene is a Hedfly attractant (17). hydrocarbons in kerosene were re-investigated. Also, in the Hawaiian 1950-1955 survey (6), 2-methylnaphthalene was indicated as active. This compound was found in kerosene and was tested for activity again. The positional isomer, 1-methylnaphthalene, has very little activity, but 2-methylnaphthalene did exhibit activity in olfactometer tests by Gothilf and in field trials by Cunningham. Although the activity of 2-methylnaphthalene is somewhat less than... 

The alkylation of naphthalene and 2-methylnaphthalene with methanol and their ammoxidation were investigated by F r a e n k e 1 et al. [22-25] on zeolites ZSM-5, mordenite and Y. In the alkylation over HZSM-5 - unlike on H-mordenite or HY - the slim isomers, namely 2-methylnaphthalene as well as 2,6- and 2,7-dimethylnaphthalene, again clearly predominated. These authors suggest that such shape selective reactions of naphthalene derivatives occur at the external surface of zeolite ZSM-5, in so-called "half-cavities" [22, 24, 25]. D e r o u a n e et al. [26,27] went even further and generalized the concept of shape selectivity at the external surface. Based, in part, on Fraenkel s experimental results, Derouane [26] coined the term "nest effect". This whole concept, however, is by no means fully accepted and has recently been severely questioned in the light of results obtained in catalytic studies with a much broader assortment of ten-membered ring zeolites [28]. 

In a preliminary screening, the alkylation of 2-methylnaphthalene was studied using a variety of acid zeolites with different pore widths. In principal agreement with the earlier work of Fraenkel et al. [22-25] it was found that the best selectivities for the slim alkylation products, i. e., 2,3-, 2,6- and 2,7-dimethylnaphthalene, are obtained on HZSM-5 and HZSM-11. On these catalysts it was observed that the alkylation is always accompanied by the undesired isomerization into 1-methylnaphthalene. Moreover, a peculiar deactivation behavior was encountered With time on stream, the yield of 1-methylnaphthalene always dropped while the yield of alkylation products remained practically constant or even slightly increased. An example for the conversion and yield curves is given in Fig. 4. The distribution of the dimethylnaphthalene isomers is shown for the same experiment in Fig. 5. Bearing in mind that in equilibrium one would expect roughly 12 mole-% of each of the slim isomers, the... 

In additional experiments, HZSM-5 was precoked by converting methanol alone (into hydrocarbons) at 400 °C. Afterwards the zeolite was exposed to the 2-methylnaphtha-lene/methanol mixture, under the usual reaction conditions. The initial yield of 1-methylnaphthalene was significantly reduced (1.5 % compared to 4 % for the fresh catalyst, cf. Fig. 4). Furthermore, the initial content of 2,6- + 2,7-dimethylnaphthalene in the dimethyl-naphthalene fraction was 84 % instead of 70 % for the fresh catalyst. In another run, HZSM-5 was loaded with 0.5 wt.-% of Pt, and H2 was used as carrier gas instead of N2. Under these conditions, the formation of coke was avoided or at least drastically diminished. In-line with our model, no changes in the product yields and in the distribution of the dimethylnaphthalene isomers were observed with time on stream. 

However, Fraser et al. (1998) noted that this canister sampling technique may underestimate the methyl-naphthalenes. Thus, their methylnaphthalenes/naph-thalene ratios were lower than those obtained by Arey et al. (1989a) using Tenax-GC solid adsorbent. This may be due to significant adsorption of the methyl isomers to the canister (Arey, personal communication). Zielinska and co-workers (1996) evaluated measurement methods for VOCs up to C2() emitted from motor vehicles and reported that C8-Cl2 hydrocarbons were more stable on the Tenax cartridge than in canisters. Similar problems with canister sampling for organics are discussed in Chapter ll.A.4e. 

As discussed earlier (see Fig. 10.26), the contributions of 1- and 2-nitronaphthalenes and the methylni-tronaphthalene isomers to the vapor-phase mutagenicity of extracts of daytime and nighttime samples of ambient air in Redlands, California, were determined by Gupta and co-workers (1996) and shown to be major contributors to the overall vapor-phase mutagenicity of ambient air. Furthermore, the researchers demonstrated that both daytime OH radical initiated and nighttime N03 radical initiated reactions of naphthalene and the methylnaphthalenes are important in pol-... 

Analytical studies of the tergal secretions of male B. germanica have identified a number of volatile compounds, none of which has so far been subjected to behavioral assays on females. Brossut et al. (1975) found p-hydroxybenzyl alcohol, o-hydroxybenzyl alcohol, di- and tri-methylnaphthalene, benzothiazole, two isomers of nonyl phenol, and myristic, palmitic, and oleic acids. The fatty acids constituted > 92% of the volatile fraction given their abundance in feces and frass, and their role as putative aggregation pheromones (Wileyto and Boush, 1983 Fuchs et al., 1985 Wendler and Vlatten, 1993 Scherkenbeck et al., 1999),... 

Boron trifluoride complexes are also often applied. BF3 when used with acyl fluorides showed in some cases distinct differences compared to other catalyst-reagent combinations. For example, acylation of 2-methylnaphthalene with isoBuCOF and BF3 gives high yield (83%) of the 6-substituted isomer in contrast to AICI3 (30%).40 A similar example is shown here ... 

Figure 3. Total ion chromatogram of extractable organics in a typical lot of Ambersorb XE-340 resin (SP-2100,10-m capillary column, temperature program 50(2)-250 at 5 °C/min, 1.0-pL splitless injection). 1, naphthalene 2,1- or 2-methylnaphthalene 3, biphenyl 4, 1,V-biphenyl, 2- or 3-methyl 5, fluorene 6, anthracene-phenanthrene 7tl- or 2-phenylnaphthalene 8, pyrene 9, fluoranthene 10, terphenyl isomer 11, benzo[b]naphthothiophene isomer 12, binaphthalene isomer 13, benzofluoranthene isomer. (Reproduced from...

The most extensive work on the subject so far has been carried out by Brink and Shrieve [44]. The highest yield of 2-methyl-1-nitronaphthalene they obtained was 57% of the theoretical. This was produced by nitrating 2-methylnaphthalene at low temperatures (0-30°C) with a 70% excess of 70% nitric acid The other isomers appeared as a by-product oil. When using a 15% excess of a nitrating mixture composed of 25% HNOs, 55% H2S04 and 20% H20 the yield of 1-nitro-2-methylnaphthalene was also 57%. Dinitration took place when acetic anhydride was used. The product was in the form of a solid with m. p. 209-213°C. No determination of the structure of the dinitroproducts was carried out. 

The effect of solvent polarity on the activity and selectivity of the HBEA zeolite was examined on the acetylation of 2MN with acetic anhydride as well as on the transacylation of 2MN with isomer I. The reactions were carried out in solvents of various polarities under the following conditions temperature of 120°C, 500mg of HBEA and 35mmol of 2MN (3,43 mol.l 1), 7mmol of AA (O Smol.l 1) and 4 cm3 of solvent (sulfolane, nitrobenzene, 1,2-dichlorobenzene or 1-methylnaphthalene) for acylation and 20 mmol of 2MN (4 mol.l 1), 4 mmol of I (1 mol.l 1) in 3,3 cm3 of solvent for transacylation. The Et parameter defined by Dimroth et alu was used for characterizing the solvent polarity. 

Draw all isomers named methylnaphthalene (with a position number). Naphthalene, a planar aromatic hydrocarbon, has the structure,... 

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