Temperature in situ

Yoo C S, Akella J and Nicol M 1996 Chemistry at high pressures and temperatures in-situ synthesis and characterization of p-SijN by DAC x-ray/laser-heating studies Advanced Materials 96 ed M Akaishi et al (Tsukuba National Institute for Research in Inorganic Materials) p 175... 

In situ CO titration experiments have also been conducted on multicomposition systems, that is, inverse model catalyst. Schoiswohl et al. [68] in their studies compared the CO titration reaction on three surfaces clean Rh(l 1 1) surface, Rh (111) surface covered with large 2D V309 islands (mean size >50 nm), and Rh(l 11) surface covered with small 2D V309 islands (meansize<15 nm). Prior to CO titration, the three surfaces were exposed to 10-7 mbar 02 to form a (2 x l)-0 phase at room temperature. In situ STM was used to follow the titration reaction in the presence of 10 x-10 7 m liar CO. CO titration on the clean Rh(l 1 1) surface or the Rh(l 1 1) surface with large V309 islands exhibits similar reaction kinetics. Figure 3.19 shows... 

Several nickel catalysts for the carbonylation of methanol have been reported,54"57 and an IR study has been described.58 The carbonylation of MeOH to form MeOAc and HOAc was studied using phosphine-modified Nil2 as the metal catalyst precursor. The reaction was monitored using a high-pressure, high-temperature, in situ Cylindrical Internal Reflectance FTIR reactor (CIR-REACTOR). 

Cracking tendency, crystallization temperature, in situ atmosphere, active nucleation sites. 

A thorough investigation has shown that the Tanigawa amination of alcohols, in which the corresponding alkoxide (282) is treated in DMF with A-methyl-A-phenylamino-triphenylphosphonium iodide (283) and a secondary amine at 80 °C, does not proceed at this temperature. In situ generation of the A.A-dimethylamino analogue (284) by reaction of (283) with dimethylamine, however, does lead to a smooth reaction at 90 °C. The proposed mechanism involves a pentacoordinated intermediate (285). " ... 

Figures 3.24(a) and (b) show morphodroms of silicate crystals growing from silicate solutions Fig. 3.24(a) shows the results of observations on quenched products, and Fig. 3.24(b) summarizes the results obtained by a high-temperature in situ observation method of growth [23]. In these cases also, as apart from the liquidus of solid-solution component, it is seen that the morphology of crystals changes from polyhedral, through hopper, to dendritic, then spherulitic. The predictions described in Section 3.12 are thus confirmed by experiment.

Few authors considered the reactivity of hydroxyl groups at catalyti-cally interesting temperatures. In situ infrared spectroscopy showed that in the cumene cracking reaction the 3550 cm-1 hydroxyls in a HY sample are only affected above 325° C. The 3650 cm-1 hydroxyl decreased in intensity at 250° C (6). During the cracking of hexane on a similar sample the gradual deactivation of the catalyst is accompanied by the progressive... 

Low Temperature, in situ. Direct Nucleophilic Acylation with the RLi/CO Reagent... 

Direct Nucleophilic Acylation by the Low Temperature, in situ Generation of Acyllithium Reagents a-Hydroxyketones from Ketones Synthesis of 3-Hydroxy-2,2, 3-trimethyloctan-4-one from Pinacolone R. Hui and D. Seyferth, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139... 

Hui, R. Seyferth, D. Direct nucleophilic acylation by the low-temperature, in situ generation of acyllithium reagents a-hydroxy ketones from ketones 3-hydroxy-2,2,3-trimethyloctan-4-one from pinacolone. Org. Synth. 1993, Coll. Vol. VIII, 343-346. 

Seyferth, D. Weinstein, R. M. Hui, R. C. Wang, W.-L. Archer, C. M. Synthesis of a-hy-droxy ketones by direct, low-temperature, in situ nucleophilic acylation of aldehydes and ketones by acyllithium reagents./. Org. Chem. 1992, 57, 5620-5629. 

Bjorgen, M., Lillerud, K. P., Olsbye, U., Bordiga, S. and Zecchina, A. 1-Butene oligomerization in Bronsted acidic zeolites mechanistic insights from low-temperature in situ FTIR spectroscopy. J. Phys. Chem. B, 2004, 108, 7862-7870. 

S.K. Verma, G.M. Raynaud, R.A. Rapp. Hot-stage scanning electron microscope for high-temperature in-situ oxidation studies // Oxid.Metals.- 1981.- V.15, No.5/6 -P.471-483. 

DIRECT NUCLEOPHILIC ACYLATION BY THE LOW TEMPERATURE, IN SITU GENERATION OF ACYLLITHIUM REAGENTS a-HYDROXY KETONES FROM KETONES 3-HYDROXY-2,2,3-TRIMETHYLOCTAN-4-ONE FROM PINACOLONE (4-Octanone, 3-hydroxy-2,2,3-trimethyl-)... 

Methane high-temperature, in-situ cracking to carbon and easily disposed of gaseous by products is practiced in the carbon/graphite composites industry where additional layerings of amorphous or microstructured carbon deposits are fabricated on preformed scaffolds. These are utilized primarily in the aerospace industry. Thin diamond coatings are also fabricated by the low-vacuum, in-situ chemical vapor deposition from methane decomposition. 

Compounds 5,6,7, and 8 are liquids at room temperature and a low temperature in situ crystallization was performed on the diffractometer using a miniature zone melting procedure with focused infrared light or C02 laser beam [/]. All bond lengths given are corrected for libration [54]. 

Other cyclizing agents include the Vilsmeier-Haack reagent prepared from DMF and phosphoryl chloride (27CB119) which permits the formylation and cyclization of 4,5-diaminopyrimidines to be carried out at low temperatures (6UCS5048) and is especially valuable for the preparation of chloropurines from chloropyrimidines. A modified Vilsmeier-Haack procedure which involves cyclization of an intermediate azomethine (253) at low temperatures in situ has also been applied to chloropurine synthesis (6UCS5048). 

J. M. Thomas, C. Williams and T. Rayment, Monitoring cation-site occupancy of nickel-exchanged zeolite Y catalysts by high-temperature in situ X-ray powder diffractometry, J. Chem. Soc. Faraday Trans. 2, 1988, 84, 2915. 

Dubrovinsky L. S., Saxena S. K., and Lazor P. (1998) High-pressure and high-temperature in situ X-ray diffraction study of iron and corundum to 68 GPa using an internally heated diamond anvil cell. Phys. Chem. Mineral. 25, 434—441. 

The catalysts (50 mg) were heated up to 673 K in He at a rate of 6 K/min and pretreated at this temperature in situ either in He or in a mixture of 5% HgS in H2 for 1 h. Thiophene HDS test reactions were carried out at 673 K and atmospheric pressure in a flow reactor system (30 cm min flow of 3% thiophene in Hg). Thiophene and the products were detected by GC. The conversion is the fraction of thiophene converted to coke and gaseous products, the yield is the fraction of thiophene converted to gaseous products. The catalytic properties were characterized by activities in C-S hydrogenolysis without C-C bond breaking (yield - (Ci+Cj+Cg products)), cracking (yield - C4 products), and coking (conversion - yield). The catalytic conversions determined after 5 minutes time on stream are discussed here, because all samples deactivated fast due to coke formation. 

Skeletal methyl substitution in the aminoolefin can increase the rate of cycliza-tion very strongly. Thus, for the cyclization of 2,2-dimethyl-l-amino-4-pentene (eq. (3)) the highest TON of 95 mol amine/(mol La) per h at 25 °C was obtained. By variable-temperature in-situ NMR studies of the catalytic solution... 

The extent of reduction of the titania support was found to be a function of the reaction temperature. In situ electron diffraction analysis showed that the oxide underwent transformation from TiOo to Ti4O7 at 1070 K (see inset of Figure 5 and Table II). This pattern was not found at lower temperatures however, it is possible that Ti407 was formed in the vicinity of the nickel under these conditions but that its pattern was masked by the strong rutile signal. 

---