Temperature naphthalene

Lin, S.D., and C. Song, Noble metal catalysts for low-temperature naphthalene hydrogenation in the presence of benzothiophene. Catal. Today, 31, 93-104 (1996). 

Naphthalene Metalation hy Potassium in THF at Room Temperature Naphthalene Carbanions ... 

At low temperatures naphthalene-1-sulfonic acid predominates whereas at higher temperatures (up to 160°C) the 2-product is formed in higher yields (85 percent). Further sulfonation at 150 to 160°C gives rise to di-, tri-, and tetra-sulfonic acids. The important naphthalene-1, 3,6-trisulfonic acid can be obtained directly from naphthalene by progressive sulfonation with fuming sulfuric acid first at 40°C, then at 60°C, and finally at 150 to 155°C [11]. 

Mechanism of the reaction. At ordinary temperatures naphthalene is inert to oxygen and at high temperatures burns with a smoky flame. The final products of combustion are, as usual with hydrocarbon oxidation, carbon dioxide and water. Its heat of combustion is 1,233,000 gram calories per gram mol at 20° C. Studies on the mechanism of combustion have shown that a stepwise process involving successive amounts of oxygen is effective. 

Fig. 6.4. The logarithm of the solubility of solid naphthalene (expressed as a mole fraction) as a function of reciprocal temperature. naphthalene in benzene, O naphthalene in cyclohexane. The solid line is calculated using the ideal-solubility equation.

Lin, S.D., and C. Song. Noble Metal Catalysts for Low-Temperature Naphthalene Hydrogenation in the Presence of Benzothiophene. Catalysis Today, 1996, 31 (1), 93-104. Matsuda, T., K. Yogo, Y. Mogi and E. Kikuchi. Shape Selective Catalysis by ZSM-5 in Disproportionation of 2-Methylnaphthalene. Chemistry Letters, 1990, 1085-1088. 

The first set of experiments involved fluorescence resonance energy transfer (FRET) between the naphthalene and pyrene-laheled polymers. A 5 1 mixture of PNIPAM-Py to PNIPAM-Na was used. When assembled in micelles, the pyrene acts as a quencher to the naphthalene, leading to high pyrene fluorescence and low naphthalene fluorescence. When the mixture is added to DMPC (liquid phase) or DSPC (gel phase) vesicles at room temperature, naphthalene fluorescence is increased, while pyrene fluorescence is dramatically decreased. This effect is not seen with the PNIPAM-Py-Na polymer, so the reduction in FRET is not due to the hydrophobic environment. This means that the hydrophobic anchors of the PNIPAM-Py and the PNIPAM-Na likely enter the membrane and the dyes are moved apart from one another. The fact that the anchor appeared to insert into the gel-phase DSPC membrane was somewhat surprising. The authors attribute the effect to defects between crystalline domains in the membrane. To test if the LCST transition still occurs when the polymers are anchored to the membrane, differential scanning calorimetry (DFC) was used. The LCST transition of the PNIPAM-Py/PNIPAM-Na mixture in solution was observed in the DFC ttace. When combined with DSPC or DMPC vesicles, the same peak was observed, indicating that the transition does indeed stiU occur, even in the presence of the lipid. 

Lin, S.D., and Song, C. Noble Metal Catalysts for Low-Temperature Naphthalene Hydrogenation in the Presence of Benzothiophene. Catalysis Today, 1996,31(1), 93-04. 

Usually prepared on the large scale by caustic soda fusion of sodium naphthalene-1-sulphonate, but can also be obtained by high-temperature alkaline digestion of... 

Schaffer s acid, CioHg04S. 2-hydroxy-7-naphthalene sulphonic acid. Obtained by sulphonating 2-naphthol with a small amount of sulphuric acid at a higher temperature than is used for the preparation of crocein acid. A valuable dyestuff intermediate. 

Molten naphthalene at its melting point of 82°C has the same density as does water at this temperature. Suggest two methods that might be used to determine the naphthalene-water interfacial tension. Discuss your suggestions sufficiently to show that the methods will be reasonably easy to cany out and should give results good to 1% or better. 

Much of our knowledge of the frequency dependence of VER rates in polyatomic molecules stems from low-temperature studies of molecular crystals [2] such as pentacene (PTC 221 4) guest molecules in a crystalline naphthalene (N C,., H ) host. In naphthalene, the phonon cut-off frequency is -180 cm [97]. At low temperature,... 

Effect of impurities upon the melting point. Let us take a specific example and examine the effect of the addition of a small quantity of naphthalene to an equilibrium mixture of pure solid and liquid a-naphthol at the temperature of the true melting point (95 5°) at atmospheric pressure. 

The naphthalene wUl dissolve in the liquid a-naphthol and, according to Raoult s law, the vapour pressure of the latter will be reduced. Hence a-naphthol will pass preferentially into the liquid phase and, if the external temperature is maintained at 95 5°, the ultimate result will be the complete melting of the solid a-naphthol since melting requires heat and no heat is imparted to the system, the temperature will fall. 

A somewhat different method of plotting the results will help the reader to appreciate the significance of the eutectic temperature. In Fig. 1,11, 2 melting points are plotted against composition. The curve AC portrays the decreasing melting point of a-naphthol as naphthalene is added up to a mol fraction of 0 605. The curve BG represents the... 

The sulphonation of toluene at 100-120° results in the formation of p-toluene-sulphonic acid as the chief product, accompanied by small amounts of the ortho and meta isomers these are easily removed by crystallisation in the presence of sodium chloride. Sulphonation of naphthalene at about 160° 3uelds largely the p-sulphonic acid at lower temperatures (0-60°) the a-siil-phonic acid is produced almost exclusively. 

The unit Kureha operated at Nakoso to process 120,000 metric tons per year of naphtha produces a mix of acetylene and ethylene at a 1 1 ratio. Kureha s development work was directed toward producing ethylene from cmde oil. Their work showed that at extreme operating conditions, 2000°C and short residence time, appreciable acetylene production was possible. In the process, cmde oil or naphtha is sprayed with superheated steam into the specially designed reactor. The steam is superheated to 2000°C in refractory lined, pebble bed regenerative-type heaters. A pair of the heaters are used with countercurrent flows of combustion gas and steam to alternately heat the refractory and produce the superheated steam. In addition to the acetylene and ethylene products, the process produces a variety of by-products including pitch, tars, and oils rich in naphthalene. One of the important attributes of this type of reactor is its abiUty to produce variable quantities of ethylene as a coproduct by dropping the reaction temperature (20—22). 

Some selected chemical and physical properties of naphthalene are given in Table 1. Selected values from the vapor pressure—temperature relationship for naphthalene are Hsted in Table 2, as are selected viscosity—temperature relationships for Hquid naphthalene. Naphthalene forms a2eotropes with several compounds some of these mixtures are Hsted in Table 3. 

Table 2. Selected Values of Vapor Pressure—Temperature and Viscosity—Temperature Relationship s for Naphthalene ...

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