Naphthalene deuterium effect

Considering the deuterium effect on naphthalene, Ci0H8, in which all the hydrogen atoms are replaced by deuterium, the Franck-Condon factor is decreased and consequently the rate of internal conversion... 

Temperature, pressure and deuterium effects on the phosphorescence decay-rate constant of naphthalene in single crystals of durene show that photo-induced hydrogen abstraction... 

In 1966 Stryer [463] and Wehry and Rogers [464] reported deuterium effects on acid dissociation in excited states. Stryer studied a collection of naphthalene derivatives, phenols, and indoles, and concluded that both the forward and reverse reaction rates were slower in D2O than in H2O. Wehry and Rogers examined a series of phenols and aromatic carboxylic acids and found that for the phenols the pK s in the excited singlet states were about 6-7 pK units lower than in the corresponding ground states. In contrast, the excited-state pK s of benzoic and naphthoic acids were found... 

In the spent solvents from E10, Table II, naphthalene and tet-ralin were the major products, and the four others were minor products which totaled 8 mole %. In El9, Table III shows that 20 mole % of the four minor products were formed, indicating that an appreciable fraction of tetralin was converted to species less effective in the donor process. Protium from the coal, deuterium from the gas phase or deuterium from the Tetralin is needed to form these products. An examination of the isotopic composition of each of the four products as shown in the bottom halves of Tables II and III allows observations to be made about their formation. 

The importance of the strength of tt complex adsorption on the reaction rate through the operation of displacement effects is further demonstrated by naphthalene randomization reactions. Naphthalene exchanges very slowly with deuterium oxide. That this is due to the displacement of water by normal naphthalene and not due to a toxic side reaction, such as polymerization, is shown in randomization experiments with mono a-deuterated naphthalene. Randomization is completed within 24 hours at 120°, whereas no significant deuteration occurs under the same reaction conditions with water. This result furnishes additional proof for the dissociative exchange mechanism. 

It is clear that deuterium as a substituent has the electron-donating effect. In other words, it can decrease electron affinity of the whole molecule. Potentials of reversible one-electron reduction for naphthalene, anthracene, pyrene, perylene, and their perdeuteriated counterparts indicate that the counterparts exhibit slightly more negative potentials (Goodnow and Kaifer 1990, Morris and Smith 1991). For example, the measurable differences in the reduction potentials are equal to -13 mV for the pair of naphthalene-naphthalene-dj or -12 mV for the pair of anthracene-anthracene-djo. The possible experimental error does not exceed 2 mV (Morris and Smith 1991). In another example, in DMF with 0.1 M n-Bu4NPFg, the deuterated pyrenes were invariably found to be more difficult to reduce than pyrene itself. The largest difference observed, 12.4 mV, was between perdeuteriated pyrene and pyrene bearing no deuterium at all with standard deviations between 0.2 and 0.4 mV (Hammerich et al. 1996). 

When hypofluorous acid reacts with aromatic substrates 7 the isomeric distribution of phenols formed suggests the nature of the transformation is electrophilic, rather than radical 4-methoxy(2-2H)phenol (8) isolated from (4-2H)anisole shows a marked NIH effect (77% incorporation of deuterium).11 A similar reaction with naphthalene gives a mixture of up to three products in low yield (1-naphthol 2.9%, 2-naphthol 0.75% and 1.4-naphthoquinone 7.4%).9... 

Rate constants for deuterium or tritium exchange of benzene, naphthalene, and other aromatic molecules have been measured in concentrated solutions of sulfuric or perchloric acid. Conveniently, Cox has extrapolated values to aqueous solution from plots of log/cx against Xa and corrected them for isotope effects (e.g., k /kp) to yield kA.72... 

To confirm reaction scheme (4) for the formation of naphthalene and biphenyl, phthalic anhydride was allowed to react with benzene-dx (Fields and Meyerson, 1966c). Barring an appreciable isotope effect, two-thirds of the naphthalene should contain a deuterium atom and one-third only protium. Biphenyl arises in two ways insertion of benzyne into a C—H bond of benzene and pyrolysis of benzene. Biphenyl from benzyne insertion should form with retention of the deuterium atom biphenyl from benzene pyrolysis should—again ignoring any isotope effect—be d0, dlt and dz on the statistical basis of losing two, one, or zero deuterium atoms from a total of twelve protiums and deuteriums in the over-all reaction of two benzene molecules. The amount of biphenyl-... 

The observations that the pH-independent reactions of deuterium-labeled 5-met-hoxyindene oxide and 6-methoxy-1,2,3,4-tetrahydronaphthalene-1,2-oxide show significant primary kinetic deuterium isotope effects for the ketone-forming reactions, whereas the pH-independent reactions of deuterium-labeled naphthalene oxide and benzene oxide do not, are quite puzzling. Clearly, more work needs to be done to fully understand why transition-state structures for rearrangement of arene oxides to phenols differ from those for rearrangement of benzylic epoxides to ketones. 

The inhibitory effects of deuterium on the cellular level were not reversed by gibberellic acid, naphthalene-acetic acid or indoleacetic acid. In some instances the inhibitory effects on growth were even greater than that attributable to the D2O in the nutrient. It is interesting to note that maleic hydra-zide, usually considered to be a plant growth inhibitor, actually stimulated the growth of peppermint cultured in deuterated media. 

Stemlicht H, McConnell HM (1960) Effect of deuterium substitution on the lifetime of the phosphorescent triplet state of naphthalene. J Chem Phys 33 302-303... 

The substituted cyclobutenone (391) and its derivatives have been thermo-lysed to substituted naphthalenes. Full details of the primary and secondary deuterium kinetic isotope effect investigation into the mechanism of the ene reaction of perfluorocyclobutanone and allene have now been reported. ... 

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