Naphthalene, exchange with

When a bituminous coal was extracted with naphthalene-d8 at 380°C under N2, 4% of its protiurn content was exchanged with deuterium in the naphthalene-d8. Most of the protiurn was incorporated into the H position of naphthalene-d8, and the ratio of H to, Hp was 3.5. 

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. 

The only way to introduce two different electrophilic fragments in compounds such as 508 is to have a starting material with different halogens. This is the case with 510, which could be lithiated (bromide-lithium exchange) with t-butyllithium in THF at — 100°C giving intermediates 511, which reacted with a carbonyl compound R R CO and, after naphthalene-catalyzed lithiation, gave the new functionalized organolithium intermediate 512. Final reaction with 3-pentanone followed by hydrolysis yielded mixed products 513 (Scheme 142) °. 

This means that the electron goes from naphthalene A with a particular set of +V2, —V2 proton nuclei to naphthalene B with a different set. The result is that the lines broaden and, if the exchange is very fast, the splitting vanishes. Because the splittings are about 5 gauss (14 MHz), the mean lifetime before exchange has to be about 10-8 sec or less to obscure the splitting (see Sections 27-1 and 27-2). 

The a-position in naphthalene (and other condensed polycyclic aromatics) is sterically hindered. Hodges and Garnett have shown, for example, that at 100°C and in the presence of Pt(II)-salts the /1-hydrogen exchanges with deuterium 28 times faster than the a-hydrogen (55). This could suggest that Pt-catalyzed direct C6-cyclization will also favor the /3-position. 

The spent naphthalene-hs was examined by XH NMR for structural changes in the solvent. No hydrogenation of the naphthalene was detected. The naphthalene-ds was examined to determine the amount of deuterium which was exchanged with protium in the coal. After 10 h, 21.1% of the deuteriun in the a and e positions of naphthalene had exchanged. The a position was the most active position for exchange. 

The purpose of the final cooler is to remove the heat of compression added by the exhauster and to cool the gas to its final temperature so that downstream absorbers will operate more efficiently. Final cooling is typically achieved by direct contact with the cooling medium, either water or oil. An important function of final cooling is removal of naphthalene. In final coolers using wash oil, the naphthalene dissolves in the oil, and a side stream is steam stripped to remove the naphthalene. If water cooling is used, the condensed naphthalene must be absorbed by contacting the water with tar. The tar is continuously exchanged with fresh tar to prevent naphthalene buildup. 

They may be prepared by heating Cr(CO)g or Cr(CO)3(NH3)3 in the arene as solvent (Scheme 10.27) or, when use of excess arene is undesirable, by exchange with the naphthalene complex 10. The procedure works well for electron-rich arenes, but is of no value for electron-deficient aromatic compounds. Decomplexation can subsequently be... 

Solid-phase extraction of various analyte complexes on e.g. microcrystalline naphthalene (Ni [23] and Cu [24] with nitroso-R salt and tetradecyldimethylbenzylammonium chloride), ammonium tetraphenylborate-naphthalene (U with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol) [25], chitin column (Cr(VI) with 1,5-diphenylcarbazide) [26], strong anion-exchange cartridge (Cr(VI) at pH 8) [27], Cig cartridge (CL-azo dye) [28] and minicolumn (As with ammonium diethyl dithiophosphate) [29], silica modified chemically with A-allyl- or A-phenyl-TV -propylthiourea (OSO4) [30] and Sephadex DEAE A-25 (chloride form) (V with Eriochrome Cyanine R) [31] prior to the spectrophotometric determination has recently been reported. The application of solid-phase spectrophotometry to determine nitrite and nitrate in water samples has recently been described [32]. 

Aromatic molecules such as naphthalene will emit phosphorescence when adsorbed in zeolites exchanged with heavy ions such as thallium. This was exploited in a convenient, zeolite TlY-coated optical fiber format in order to detect naphthalene.[131]... 

Figure 3.18 Change in electrical resistance of an anion exchange membrane (strongly basic anion exchange) with and without anionic polyelectrolyte layers in the presence of sodium tetradecyl sulfate (STS). 1. without the layers and with STS 2. with the layers (immersion time 4 h) and with STS 3. with the layers (immersion time 24 h) and with STS 4. with the layers and without STS 1 left vertical axis 2,3 and 4 right vertical axis. After an anion exchange membrane had been immersed in 100ppm anionic polyelectrolyte (polycondensation product of sodium naphthalene sulfonate and formaldehyde MW ca. 1000) solution for the respective time at room temperature, electrodialysis was carried out at a current density of 2.5 mAcmr2 using 0.10 N sodium chloride solution containing 2.16 X 10 3 mol dm3 of STS.

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