2.7- Dimethyl naphthalene, oxidation

Similar regiospecific syntheses employing PMBs and diaLkylnaphthalene have been used to prepare 2,6-dimethyl naphthalene [581-42-0] which is oxidized to the corresponding 2,6-naphthalenedicarboxyHc acid [1141-38-4] also used as a monomer for Hquid crystal polymers. 

Voluminous studies have been made to distinguish the reactivity of singlet oxygen, triplet oxygen, and electron transfer-generated superoxide (228). For example, while superoxide gives both endoperoxide and side chain oxidation of 1,4-dimethyl-naphthalene, eq. 73 (229),... 

The reaction of the relatively unstable phosphine oxide (20) with dimethyl acetylenedicarboxylate gives dimethyl naphthalene-2,3-dicarboxylate. This... 

The most apparently desirable of the minor components is the 2,6-dimethyl naphthalene which can be used to make naphthalene-2,6-dicarboxylic acid, which in turn can be used to make special polyesters (3). Following oxidation of the alkylated naphthalenes (the alkyl groups do not necessarily have to be methyl, but the substitution pattern is important) the resulting dicarboxylic acids should be readily marketable. However, since the overall yields of naphthalene derivatives in the synthetic gasoline are low, this fraction is unlikely to be of commercial value in the near term. This is unfortunate, because these compounds are also unsuitable for gasoline as their boiling points lie outside the required specification. 

The HO radical-initiated atmospheric oxidation of 2,7-dimethyl naphthalene (27DMN) has been investigated at BBIK and G3MP2-RAD//BH HLYP levels. The adduct Rl is formed by addition of HO to the C(l) position and reacts with atmospheric O2 via two slow comparable pathways consisting of direct H abstraction... 

Cyclization of 3,3-dimethyl-2-hydroximino-4-tosyloxybutane (272) with 1,6-bis-(dimethylamino)naphthalene is reported to occur via iV-alkylation to give the 1-azetine Af-oxide (273) as an unstable oil which decomposes over a few days at room temperature (74TL4283). 

Treatment of isoquinoline tV-oxide (55) with sodium hydride in dimethyl sulfoxide results in ring expansion, albeit in poor yield, to the 3//-3-benzazepine 56, along with a trace of naphthalene (0.8%), and much tar.26... 

Photo-oxidation of protoporphyrin IX and its dimethyl ester Norrish type II reaction of amphiphilic ketoacid Quenching of naphthalene fluorescence by Ni2 +... 

Although the superior properties of PEN have been known for many years, the unavailability of the naphthalate monomer has delayed the development of commercial markets, until relatively recently (1995) when the Amoco Chemical Company offered high purity naphthalene-2,6-dimethyl dicarboxylate (NDC) in amounts of up to 60 million pounds per year. This diester is produced by a five-step synthetic route, starting from the readily available compounds, o-xylene and 1,4-butadiene [3], Prior to this, the NDC diester was obtained by extraction of 2,6-dimethylnaphthalene (DMN) from petroleum streams, where it was present in relatively low abundance. Oxidation of DMN to crude 2,6-naphthalene dixcarboxylic (NDA) is conducted by a similar process to that used for conversion of p-xylcnc to purified terephthalic acid (TA), crude NDA is esterified with methanol, and is then distilled to yield high purity NDC. Other companies (e.g. the Mitsubishi Gas Chemical Company) followed Amoco s introduction with lesser amounts of NDC. Teijin [4] has manufactured PEN for many years for its own captive uses in films. 

PEN is produced from 26DMN analogously to how PET is produced fromp-xylene. The 26DMN is oxidized to dimethyl 2,6 naphthalene dicarboxylate and then polymerized with ethylene glycol to produce PEN. The 26DMN can be synthesized by a number of methods mentioned by Lillwitz [44]. 

Later in 1965, Chart and Davidson [2] reported the first example of cyclometal-lation of an sp C—H bond in [Ru(dmpe)2] (3) dmpe = dimethyl phosphinoethane. These authors found not only that this complex spontaneously cyclometaUates at the phosphorus methyl groups to produce complex [Ru(H)(CH2P(Me)CH2CH2PM 62)(dmpe)] (4 see Scheme 13.4) (a later examination by Cotton and coworkers [9] of this compound provided crystallographic evidence that the cyclometalated form of [Ru(dmpe)2] is in fact a dimer (5) of the type shown in Scheme 13.3), but also that the system reacts with free naphthalene via the oxidative addition of a C—H bond to the zero-valent rathenium center to produce complex [cis-Ru(H)(2-naphthyl)(dmpe)2] (6). This species was in equilibrium with the r-coordinated naphthalene ruthenium complex [Ru(naphthalene)(dmpe)2] (7) (Scheme 13.4). 

Tanaka et al. (1996,2000) studied the behavior of a series of naphthalene derivatives in AN solution containing NaN02 and CF3SO3H at 0°C in air. Naphthalene showed very low reactivity, and most of the starting material was recovered after the reaction. In case of 1-methylnaphthalene, a coupling reaction took place to produce 4,4 -dimethyl-l,T-binaphthyl in 91% yield alongside mononitro derivatives of the dimer in 1.5% yield. However, when the reaction is carried out on the same conditions but in inert (Nj) atmosphere, the yield of the dimer decreased from 97 to 15%, and no mononitro derivatives were formed. Therefore, the oxidation of NO with O2 to form NO2 (after the electron transfer to NO from 1-methylnaphthalene) is an obvious step of the reaction depicted in Scheme 4.42. 

Synthesis of racemic naproxene Friedel-Crafts acylation (aluminum chloride - nitrobenzene) of p-naphthol methyl ether affords 2-acetyl-6-methoxy naphthalene, which, when treated with either dimethyl sulfonium or dimethylsulfoxonium methylide, gives 2-(6-methoxynaphthalen-2-yl)propylene oxide. Treatment of the latter with boron trifluoride etherate in tetrahydrofuran gives 2-(6-methoxynaphthalen-2-yl)propionaldehyde, which is oxidized using Jones reagent (4 M chromic acid) to yield the racemic 2-(6-methoxynaphthalen-2-yl)propionic acid. 

REPELLENT. 1. A substance that causes and insect of animal to turn away from it or reject it as food. Repellents may be in the form of gases (olfactory), liquids, or solids (gustatory). Standard repellents for mosquitos, ticks, etc., arc dtronella oil, dimethyl phthalatc, w-butylmcsityl oxide oxalate, DEET, and 2-ethyl hexanediol-1,3. Actidione is the most effective rodent repellent, but is too toxic and too costly to use. Copper naphthenate and lime/sulfnr mixtures protect vegetation against rabbits and deer. Shark repellents are copper acetate or formic acid mixed with ground asbestos. Bird repellents are chiefly based on taste, but this sense varies widely with the type of bird so that generalization is impossible. G -Naphthol, naphthalene, sandalwood oil, quinine, and ammonium compounds have been used, with no uniformity or result. 

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