Naphthalene fluorination

Tanaka s research group reported the analysis of a series of alkylbenzenes (C6H5-(CH2) H, n = 0-6) and PAHs (naphthalene, fluorine, phenanthrene, anthracene, pyrene, triphenylene, and benzo[a]pyrene) on tetramethoxysilane-based macroporous silica gel monoliths and achieved efficiencies up to 80000 plates per meter. 

Eused-ring polycycHc fluoroaromatics can be made from the corresponding amino fused-ring polycycHc or from preformed fluoroaromatics, eg, 4-fluorophenyl-acetonitrile [459-22-3] (275). Direct fluorination techniques have been successfully appHed to polycycHc ring systems such as naphthalene, anthracene, benzanthracenes, phenanthrene, pyrene, fluorene, and quinoHnes with a variety of fluorinating agents xenon fluorides (10), acetyl hypofluorite (276), cesium fluoroxysulfate (277), and electrochemical fluorination (278,279). 

Fluorination of naphthalene in a stream of dilute fluorine over cobalt trifluoride yields a mixture of perfluorodecalins and partially fluorinated naphthalene derivatives that are fully fluorinated to perfluorodecalins by a subsequent treatment with dilute fluorine [23] Perfluorodecalins are also final products ot fluorination of tetralin over cobalt trifluoride at 250 °C. A more thorough investigation of this reacPon revealed seven additional compounds as products and intermediates [//] (equation 6). 

Perfluorodecalin is transformed to octakis(phenylthio)naphthalene by phenyl thiolate in dipol ar aprotic solvents The crucial first step of this reaction may involve an elimination of the tertiary fluorine atoms, which would lead to a symmetric perfluorobicyclic olefin as an intermediate [65] (equation 58). 

Many expensive reductions such as the Birch reduction of naphthalene to isotetralin, benzene to cyclohexene, with metallic sodium and liquid ammonia, or reduction with LiAlHa, can generally be carried out electrochemically at much lower cost and under safe conditions. Electrochemical processes allow fluorinations to be carried out without using fluorine gas. Conducting polymers have been made by electrochemical processes which operate under ambient conditions, and the polymer can be synthesized, doped and shaped in film form in a single step. 

Fluidized bed reactors were first employed on a large scale for the catalytic cracking of petroleum fractions, but in recent years they have been employed for an increasingly large variety of reactions, both catalytic and non-catalytic. The catalytic reactions include the partial oxidation of naphthalene to phthalic anhydride and the formation of acrylonitrile from propylene, ammonia, and air. The noncatalytic applications include the roasting of ores and Tie fluorination of uranium oxide. 

Synthesis of Fluorinated Poly(Aryl Ether)s Containing 1,4-Naphthalene Moieties... 

On the basis of the above studies reported thus far, we have designed and synthesized a series of novel poly(aryl ether)s containing both hexafluoroisopropylidene and 1,4-naphthalene moieties. We found these new polyarylethers to have good solubility, high Tg s, and excellent thermal stability. We report herein the synthesis and characterization of these poly(aryl ether)s containing fluorinated 1,4-naphthalene moieties. 

Poly(ether ketone)s 3, 4, 5, 6, and 7 were soluble in polar aprotic solvents such as DMAc and NMP and in chlorinated solvents such as chloroform. The improved solubility of these fluorinated poly(ether ketone)s can be explained by the presence of both the flexible hexafluoroisopropylidene groups and the bulky 1,4-naphthalene moieties, which inhibit polymer crystallization and facilitate the penetration of solvent molecules between the polymer chains. 

Six novel fluorinated poly(aryl ether)s containing 1,4-naphthalene moieties were synthesized in high yield using 2,2-bis[4-( 1 -naphthoxy)phenyl]hexafluoro-propane (1). Oxidative coupling ofl yielded a polymer with high 7, low moisture absorption, and low dielectric constant that could be cast into flexible films. The low dielectric constant and low moisture absorption of 6FNE may make it useful as a dielectric insulator in microelectronics applications. 

The DMS method has not been employed yet for the generation of 117 and 123, since the dibromocarbene adducts of norbomadiene and norbornene rearrange under the usual conditions for the preparation [89]. However, they could be synthesized at -60 °C by taking advantage of tetrabromomethane and methyllithium as a source of the carbene [90] and could prove stable enough to serve as precursors of 117 and 123. On the other hand, the adducts of bromofluorocarbene to norborna-diene and norbornene having the fluorine atom in a cis-orientation should be isol-able at room temperature and hence be usable as stable precursors of 117 and 123. These variations ofthe DMS method were published on the occasion ofthe preparation of cycloadducts of l-oxa-2,3-cyclohexadiene (351) (Section 6.3.6) [35, 91], 1,2,4-cyclohexatriene (162) and 3d2-lJ-f-naphthalene (221) (Section 6.3.4) [35, 92],... 

Anodic regioselective fluorination of a-phenylsulphenylated ethyl acetates, 1-naphthalene and 2-pyridine derivatives [80], l-aryl-3-(phenylthio)oxindoles and 2-substituted-3-oxo-4-(phenylthio)-l, 2, 3,4-tetrahydroisoquinolines [81], 2-benzo-thiazolyl and 5-chloro-2-benzothiazolyl sulfides [82], a-(phenylsulfenyl)lactams [83], as well as various heterocycles such as thiolanones, oxathiolanones, dithi-olanones, 3Fl-l,4-benzoxathian-2-ones [84] in Et3N-3HF or Etr NF- HF [n = 3,4), has been reported. 

Monohalogenated Benzenes and Naphthalenes Trends in aromatic toxicities (Table IV) are somewhat obscured in these two series by the toxicities of the individual substituents (2). Fluorine and chlorine substituents are reasonably inert however, the bromine and iodine atoms, particularly the latter, are extremely toxic. In the case of inert substituents (F, Cl) the results resemble those of the alkylbenzenes in terms of steric hindrance to adsorption. 

The difference in the reactivity of benzylic versus aromatic halogens makes it possible to reduce the former ones preferentially. Lithium aluminum hydride replaced only the benzylic bromine by hydrogen in 2-bromomethyl-3-chloro-naphthalene (yield 75%) [540]. Sodium borohydride in diglyme reduces, as a rule, benzylic halides but not aromatic halides (except for some iodo derivatives) [505, 541]. Lithium aluminum hydride hydrogenolyzes benzyl halides and aryl bromides and iodides. Aryl chlorides and especially fluorides are quite resistant [540,542], However, in polyfluorinated aromatics, because of the very low electron density of the ring, even fluorine was replaced by hydrogen using lithium aluminum hydride [543]. 

Kinetic parameters of metabolism of fluorinated analogues of propanolol by cytochrome enzyme (recombinant CYP1A2) have been determined. They clearly indicate that the A-dealkylation process was 10-fold lower for the N—CH2CF3 compound with respect to propanolol itself. Hydroxylation of the naphthalene ring process is not observed in the case of propanolol but it becomes the major process with the fluoro analogue (Figure 3.13)." The same decreased metabohsm trend has also been observed with lower pKa values for CYP2D6 cytochrome enzyme." ... 

There is rather little direct experimental evidence for the intermediacy of BZ. Cyclic ketenimine K has been detected by matrix IR spectroscopy, benzazirine BZ has not. However, fluorinated and naphthalenic derivatives of BZ have been generated as persistent species in cryogenic matrices and characterized. Parent benzazirine BZ has been intercepted with ethanethiol, and certain derivatives of BZ have been trapped with... 

---