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Naphthalene photoadduct

Additions to Aromatic Hydrocarbons. A variety of photochemical additions to aromatic hydrocarbons have been reported. Benzene and its derivatives add to maleic anhydride74-76 as well as to simple olefins,77-80 isoprene,81 acetylene derivatives,79,82 and alcohols.83 The mechanism of the maleic anhydride-benzene reaction is discussed in Section IV. A.4. Naphthalene forms a photoadduct with dimethyl acetylenedicarboxylate62 and with acrylonitrile8211 while anthracene behaves similarly with maleic anhydride84 and with 1,2-benzanthracene.85 The photoaddition of several aromatic amines to anthracene has been reported to proceed via a charge transfer complex86,87 in fact, the majority of these addition reactions may proceed in this manner. [Pg.257]

Intramolecular photocycloaddition of naphthalene and anthracene has been studied by Chandross and Schiebel [327], At concentrations above 10 3 M, bi-molecular photodimerization of the anthracene occurs in deaerated methylcyclo-hexane solution. In contrast, irradiation of much more dilute ( 2 X 105 M) solutions resulted in the formation of intramolecular adduct 342 (Scheme 94). Bouas-Laurent et al. showed that the CH2—O—CH2 link is more efficient than the (CH2)3 chain in bridging the two chromophores [328], Irradiation of diethyl ether or methylcyclohexane solution of 343 (5 X 10 5 M) with a high-pressure mercury lamp and liquid filter (X > 335 nm) gave a single photoadduct 344, which was isolated quantitatively. The quantum yield of 344 is 10 times higher than that of 342. [Pg.192]

Since alcohols are less effective as hydrogen donors than amines, a PET photoaddition can occur only when the oxidized component of the reaction is the alkene. Furthermore, if the photosensitizer is chiral, the polar addition would occur in an enantiodifferentiating manner to some degree. Thus, the photoaddition of 2-propanol to 1,1-diphenylpropene, when sensitized by chiral naphthalene(di)carbox-ylates, formed the anti-Markovnikov photoadduct with enantiomeric excesses of up to 58% [53]. Unfortunately, the reaction is far from attracting synthetic interest as the yields are still too low. [Pg.81]

The reaction with benzothiophens provides a route to substituted naphthalenes by thermal ring-opening and sulphur extrusion of the photoadducts (equation 80) >... [Pg.32]

In a similar manner the photoadduct 34 of 4-phenyl-l,2,4-triazole-3,5-dione and naphthalene underwent a photochemically induced di-n-methane rearrangement to give (after hydrolysis and oxidation) a precursor 35 to naphthvalene (36). The photochemical deazetization suffered a competitive retro-[3-I-2] reaction leading to benzofulvene (37). ... [Pg.1103]

Naphthalene and triethyl benzene-1,2,4-tricarboxylate underwent photochemical additions to diphenylacetylene and to cyclooctene to give 1 1 photoadducts containing three-membered rings, but generally in low yield. [Pg.1140]

Few examples of photocycloaddition of the nitrogen-nitrogen double bond to alkenes are known and these are usually restricted to molecules in which the double bonds are held in close proximity to each other. A hitherto unknown [6 + 2] intramolecular addition to a benzene ring has been reported in the azoalkane (141) which is converted on irradiation into the 1, 2-diazetidine (142). Irradiation of 4-phenyl-4H-1,2,4-triazole-3,5-dione (143) in the presence of naphthalene, however, affords the [4 + 2] photoadduct... [Pg.394]

Photoadducts of aromatic hydrocarbons, benzene and naphthalene, and N-methylindole with acetylenic compounds often undergo electrocyclic ring opening to give stable products. The following examples are illustrative ... [Pg.284]


See other pages where Naphthalene photoadduct is mentioned: [Pg.794]    [Pg.794]    [Pg.143]    [Pg.306]    [Pg.94]    [Pg.339]   
See also in sourсe #XX -- [ Pg.705 ]




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