Solvents phenol, equilibration

Microautoclave data was also obtained with Wilsonville Batch I solvent utilizing Indiana V coal. Batch I solvent was obtained from Wilsonville in mid-1977. Other batches of recycle solvent were received later. Batch I solvent had inspections most like the Allied 24CA Creosote Oil used for start-up at the Wilsonville Pilot Plant. Succeeding batches of solvent received by CCDC showed substantial differences, presumably due to equilibration at various operating conditions. As the Wilsonville solvent aged and became more coal derived, the solvent aromaticity decreased with an increase in such compounds as indan and related homologs. The decrease in aromaticity has also been verified by NMR. A later solvent (Batch III) also showed an increase in phenolic and a decrease in phenanthrene (anthracene) and hydrogenated phenanthrene (anthracene) type compounds. 

The same authors describe an interesting interaction between phosphites (e.g. 188) and acetylenedicarboxylates in the presence of alcohols, phenols or carboxylic acids. For example, with benzoic acid present, (188) gives the ylide (189) which is in equilibrium with the isomer (190). This equilibration is very solvent dependent, and after several hours in dichloromethane solution finally yields the phosphonate (189a Scheme 31) (8iPS(10)18i). 

The cell was loaded with 10 5g phenol blue, evacuated, and pressurized with the solvent. A spectrum was obtained at a given pressure after the temperature and absorbance equilibrated. The absorption band was scanned over a range of 450-600 nm 2-3 times to obtain the average X. The reproducibility in X was 0.2 nm... 

Some further details of the mechanisms of photo-equilibration and fragmentation of cholest-5-en-3/3-o and -4-en-3/3-ol have been elucidated by the use of a variety of aromatic compounds as sensitizers.249 Reaction is favoured by use of phenolic compounds which can associate with the reactant. Fragmentation, which leads via the unsaturated aldehyde (314) to the oxetan (315), is particularly favoured by the presence of phenol, with dioxan as solvent, and is most efficient with the 4-en-3/3-oI. 

Knowles and co-workers have studied the stereochemical consequences of the presumed S>jl(P) reaction. They have shown that the methanolysis of chiral 0 0 0-substituted phenol- and 2,4-dinitrophenylphosphate and phosphocreatine (13, 14), under conditions where they were expected to react by the metaphosphate pathway, all undergo complete inversion of configuration at phosphorus. This result implies that the putative metaphosphate is not a free intermediate that it is not even long-lived enough to equilibrate with the solvent cage in which it is formed. It was concluded that the reaction must be preassociative at least in aqueous-alcoholic media. A recent report (24) has shown that the Conant-Swan fragmentation described earlier also occurs with inversion about the phosphorus atom. 

To tackle the above discussed challenge in detecting potential PCET intermediates, an intricate experimental approach has been developed to measure the rate constant of the PT step independently from the ET (see e.g. ref. 188 193). When performing experiments in unbuffered solutions, pH indicators, such as phenol red, can be used as reporters of the PT step. The rate constants obtained from the colour change of the dye correspond to the PT of interest, assuming that the equilibration between the protons in the active site and the bulk solvent is not rate-limiting. 

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