P-substituted naphthalenes

Scheme 4.17 Catalytic cycle for the formation of p-substituted naphthalenes.

Anthraquinone dyes are derived from several key compounds called dye intermediates, and the methods for preparing these key intermediates can be divided into two types (/) introduction of substituent(s) onto the anthraquinone nucleus, and (2) synthesis of an anthraquinone nucleus having the desired substituents, starting from benzene or naphthalene derivatives (nucleus synthesis). The principal reactions ate nitration and sulfonation, which are very important ia preparing a-substituted anthraquiaones by electrophilic substitution. Nucleus synthesis is important for the production of P-substituted anthraquiaones such as 2-methylanthraquiQone and 2-chloroanthraquiaone. Friedel-Crafts acylation usiag aluminum chloride is appHed for this purpose. Synthesis of quinizatia (1,4-dihydroxyanthraquiQone) is also important. 

It is not only p-substituted phenols that have been connected by methylene groups an extended calixarene based on naphthalene units [57] has also been synthesized and its acidity constants have been measured (see Table 25 Poh and Lim, 1989, 1990). In contrast to the calix[4]arenes, the pKa of the expanded calixarene [57] did not differ much from the of the analogue [58]. This may have two explanations (i) the conformation of the expanded calixarene is different from phenol-based calix[4]arenes and a special stabilization of the anion does not occur, (ii) this stabilization occurs but it is also present in the analogue. A stabilization by the neighbouring... 

Betzemeier et al. (1998) have used f-BuOOH, in the presence of a Pd(II) catalyst bearing perfluorinated ligands using a biphasic system of benzene and bromo perfluoro octane to convert a variety of olefins, such as styrene, p-substituted styrenes, vinyl naphthalene, 1-decene etc. to the corresponding ketone via a Wacker type process. Xia and Fell (1997) have used the Li salt of triphenylphosphine monosulphonic acid, which can be solubilized with methanol. A hydroformylation reaction is conducted and catalyst recovery is facilitated by removal of methanol when filtration or extraction with water can be practised. The aqueous solution can be evaporated and the solid salt can be dissolved in methanol and recycled. 

MacIntyre, W.G. and deFur, P.O. The effect of hydrocarbon mixtures on adsorption of substituted naphthalenes by clay and sediment from water, Chemosphere, 14(1) 103-111, 1985. 

Quantitative Property-S T) Relationship Dickhut et al. [67] developed a QP-5VV(7 )R based on experimental mole fraction solubilities for alkylbenzenes, PAHs, PCBs, chlorinated dibenzofuranes and p-dioxins, and alkyl- and halo-substituted naphthalenes and p-terphenyls in the range 4 to 40°C ... 

In support of this view the p-amino-phenols themselves readily yield quinones. Also most p-substituted primary amines, e.g., p-diamines, p-alkylamines, such as p-toluidine, sulphanilic acid and its derivatives, behave similarly. In fact, the reaction can be used as a test for p-substi-tuted primary amines. p-Benzoquinone is usually made from aniline for the other p-quinones the p-amino-phenols, which are easily obtained by reduction of the p-nitroso-phenols and of azo-phenols, are employed. These reactions also apply, but not so widely, in the naphthalene series. 

Substituents have considerable influence on emission characteristics of aromatic compounds. Heavy atom substituents tend to reduce the fluorescence quantum yield / in favour of phosphorescence emission p. In halogen series the effect increases in the order F < Cl < Br < I. In Table 5.1 are recorded experimental data for halogen substituted Naphthalenes. 

Substitution Products.— The halogen derivatives of naphthalene include both substitution and addition products. The tetra- and penta-chlor substituted naphthalenes have already been referred to as furnishing proof that in naphthalene there are present two benzene nucleii (p. 771). Other halogen substituted naphthalenes are known but none need be discussed in detail. ... 

As we would expect, introduction of these groups opens the way to the preparation of a series of u/p/ra-substituted naphthalenes from 1-nitronaphthalene via the amine and diazonium Its, and from 1-bromonaphthalene via the Grignard reagent. 

Introduction. The quinones are intermediate products in the oxidation of the aromatic nucleus. They may be prepared in some cases by the direct oxidation of aromatic hydrocarbons. For example, anthracene, naphthalene, and phenanthrene are oxidized to the corresponding quinones by chromic acid mixtures. Quinones are prepared more conveniently by oxidation of primary aromatic amines, particularly the p-substituted amines. p-Benzoquinone is obtained by the oxidation of aniline, p-toluidine, sulfanilic acid, p-aminophenol, and other similar compounds. Similarly the a-naph-thoquinone is obtained by oxidation of 1,4-aminonaphthol, and /9-naphthoquinone by the oxidation of 1,2-aminonaphthol. In the laboratory, although it is possible to prepare p-benzoquinone by the oxidation of aniline with acid-dichromate mixture, the method is tedious and the yield poor. Since hydroquinone is used extensively as a photographic developer and is made industrially, it is more convenient to prepare quinone by its oxidation. 

The highiy oxygenated antifungai/anticancer naturai product ( )-diepoxin o was prepared in the laboratory of P. Wipf. The coupling of the two substituted naphthalene rings was achieved via the Ullmann condensation of a phenolic compound with 1-iodo-8-methoxynaphthalene. The aryl iodide coupling partner was used in excess and the condensation was conducted in refluxing pyridine in the presence of a full equivalent of copper(l)-oxide. 

The acylation of 2-substituted naphthalenes usually occurs at l-(a-) position [2]. But there are some exceptions where it can give rise to different kind of isomers by changing the reaction conditions [9]. 2-Methoxy naphthalene (2-MON) has been shown to be acetylated mostly either in l-(a)-position to yield l-acetyl-2-methoxynaphthalene or at 6-(P)-position to yield 2-acetyl-6-methoxynaphthalene depending on the catalyst and solvent systems used [10]. The a-isomer is rep)orted in most of the cases. But in the case of AICI3 catedysed acylation of 2-MON in presence of certain solvents, especially nitro compounds, a solvated nitro complex is formed by which acylation at the P-position is preferred [3]. 

TH. J. Nieuwstad, P. Klapwijk, H. Van Bekkum. Hydrogenation of Alkyl-substituted Naphthalenes over Palladium. J. Catal. 29 404-411, 1973... 

Photocyanation of aromatic compounds is dealt with in several papers this year. In the presence of an electron acceptor such as p-dicyanobenzene, aromatic hydrocarbons such as naphthalene (81), substituted naphthalenes, phenanthrene, or anthracene give mixtures of products on irradiation with sodium cyanide. The major products involve substitution of hydrogen by cyanide or addition of hydrogen cyanide to the aromatic hydrocarbon. When oxygen is present, the product mixture is less complex, and a good yield of cyano-substituted compound is obtained. It is proposed that the aromatic radical cation is involved in the... 

Irradiation of aromatic hydrocarbons such as phenanthrene, anthracene, naphthalene, and certain substituted naphthalenes in the presence of NaBH4 and m- or p-(NC)2C6H4 promotes a Birch-type photoreduction.The reaction seems to occur by electron transfer from the excited singlet state of the arene to the electron acceptor giving the arene radical cations, which are then reduced by the borohydride. Other reducing agents such as NaBH, NaBHjCN, and NaBH(OMe)3 have been found to be effective and all lead to different isomer ratios. In a mechanistically related reaction, both fluoren-9-ol and the corresponding acetate are reported to be photoreduced to the parent hydrocarbon in the presence of aliphatic amines. The products arise by photoinduced electron transfer followed by proton transfer from the amine. The yield depends on the structure of the amine and increases in the order primary < secondary < tertiary amine. In... 

Raton, J.J., R.D. Bereman, and N.J. Glass An analytical method has been developed for naphthalene and methyl substituted naphthalenes found in mainstream cigarette smoke using gas chromatography coupled with mass spectrometry 57th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 57, Paper No. 13, 2003, p. 25. 

An analysis of the triplet-triplet absorption spectra of m- and p-dicyanobenzenes and 1,3,5-tricyanobenzene indicates that the T-T bands correspond to transitions from the locally (benzene ring) excited state to the intramolecular charge-transfer state.186 T-T absorption spectra for some substituted naphthalenes have also been studied.187 An attempt to provide evidence for the formation of triplet benzyne has failed.1880... 

An example in which the regioselectivity of addition is different under kinetic versus thermodynamic control is the naphthalene series. In the addition of LiC(Me)2CN to naphthalene-Cr(CO)3, a mixture of products is observed from addition at C-o and C p in the ratio 42 58 under conditions where equilibration is minimized (0.3 h, —65°C, THF/HMPA). With the same reactants, but in THF and at 0 °C, the product is almost exclusively the a-substituted naphthalene (equation H7).i83,i89... 

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