Assisted hydrolysis

The first P-chiral hydroxy phosphoryl compounds that were enzymatically resolved into enantiomers were o-hydroxyaryl phosphines and their oxides 75. The resolution was achieved via enzyme-assisted hydrolysis of their O-acetyl derivatives 74, the most effective enzymes being CE and Upase from C. rugosa (CRL) (Equation 35). The highest enanfioselectivity was observed in the case of naphthyl derivatives (Equation 36), having a P=0 moiety. ... 

Instead of the wet chemical hydrolysis and derivatization before GC/MS analysis, methods based on pyrolysis-GC/MS with in situ thermally assisted hydrolysis and methylation or silylation can be used, as described in detail in Chapters 11 and 12. 

J.M. Challinor, Review the Development and Applications of Thermally Assisted Hydrolysis and Methylation Reactions, Journal of Analytical and Applied Pyrolysis, 61, 3 34 (2001). 

Y. Ishida, S. Wakamatsu, H. Yokoi, H. Ontani and S. Tsurge, Compositional analysis of polyunsaturated fatty acid oil by one step thermally assisted hydrolysis and methylation in the presence of trimethylsulfonium hydroxide, J. Anal. Appl. Pyrol., 49, 267 276 (1999). 

F. Cappitelli, T. Learner and O. Chiantore, An initial assessment of thermally assisted hydrolysis and methylation gas chromatography/mass spectrometry for the identification of oils from dried paint films, J. Anal. Appl. Pyrol., 63, 339 348 (2002). 

A. Asperger, W. Engewald and G. Fabian, Thermally assisted hydrolysis and methylation a simple and rapid on line derivatization method for gas chromatographic analysis of natural waxes, J. Anal. Appl. Pyrol., 61, 91 109 (2001). 

Gamier, N., Richardin, P., Cheynier, V. and Regert, M. (2003). Characterization of thermally assisted hydrolysis and methylation products of polyphenols from modern and archaeological vine derivatives using gas chromatography-mass spectrometry. Analytica Chimica Acta 493 137-157. 

The classic case of assisted hydrolysis of phosphate diesters is neighbouring... 

The hydroxide ion can modify the reactivity of a system in acid medium. This has been known for a long time and an example is used in Section 1.1. The ability of hydroxide to modify a reactant is probably most important in the base-assisted hydrolysis of metal ammine and amine complexes. The overwhelming bulk of these studies have been with Co(III), for example,... 

In order to accelerate sample preparation, new extraction methodologies such as accelerated solvent extraction (ASE) and MAE, based on the use of elevated temperature and pressure to heat the mixture sample-solvent, have been recently developed and applied for PAH extraction from meat [695] and vegetables [696-698]. Garda Falcon et al. [699] used microwave treatment with hexane to accelerate PAH extraction from freeze-dried foods. The fat extracted in this way underwent microwave assisted saponification with ethanolic KOH. Hernandez-Borges et al. [700] combined microwave-assisted hydrolysis and extraction to isolate organic pollutants from mussels, while... 

The chiral auxiliary of alkylated A-acylbornane-10,2-sultams can be liberated by the use of hydroperoxide-assisted hydrolysis using lithium hydroxide/hydrogen peroxide9 in tetrahydro-furan/water (see Section 1.1.1.3.3.4.2.1.). This furnishes the chiral acids 2 in very high optical purities, along with the auxiliary which can be recycled. Other mild methods are available20. 

The chiral chloride salt is stable for years when kept dry and in the dark, preferentially in a refrigerator at — 15 °C. When heated, the solid salt dehydrates and undergoes racemization.11 In acid solution the A-cis-[Cr(en)2Cl2] + cation aquates to A-cis-[Cr(en)2(H20)Cl]2+ followed by racemization of this complex. In acid solution, Ag+-assisted hydrolysis leads to the A-cis-[Cr(en)2(H20)2]1+ complex.12... 

He, Y, Johansson, M. and Sterner, O. (2004) Mild microwave-assisted hydrolysis of acetals under solvent-free conditions. Synth. Commun., 34 (22), 4153-4158. 

The category BAC2 (ref. 1, p. 753) referred originally to alkaline hydrolysis, but included the then relatively small class of hydrolytic reactions proceeding in neutral solution. It is our picture of this class of reactions which has changed most dramatically in the past fifteen years, with the discovery of a multitude of catalytic processes which can assist hydrolysis in neutral solutions. Alkaline hydrolysis itself can be regarded as just one example, albeit a special case, of a large class of reactions which involve nucleophilic attack on esters... 

Reaction of the anion prepared by deprotonation of a ketene thioacetal (799) (LDA or s-butyllithium) with a carbonyl compound has been shown to afford generally the product of y-addition (800) (80JOC2236). Mercury ion-assisted hydrolysis of the 5-hydroxy ketene thioacetal provides access to a y-lactone (801 Scheme 187). The y-selectivity of carbonyl substrates is to be contrasted with the a-selectivity generally exhibited by alkyl halides in... 

The reaction of 5-methylpyrazole with cadmium tetrafluoroborate gives a complex which is formulated as the tetrameric species [Cd4F4Li2] [BF. 447 It is thought that the fluoride ion is generated by the (possibly metal-assisted) hydrolysis of tetrafluoroborate, and that a heterocubane Cd4F4 cluster core (63) is formed. 

Because sucrose is hydrolyzed by enzymes that specifically assist hydrolysis of both a glycosides (such as yeast a-glucosidase) and /3-fructosides (such as invertase), it is inferred that the glucose residue is present as an a glucoside and the fructose residue as a /3 fructoside. If so, the remaining uncertainty in the structure of sucrose is the size of the rings in the glucose and fructose residues. 

XPS will aid in understanding specifically the surface of the black deposit covering pictographs in Little Lost River Cave in Idaho. This work will complement other bulk analyses carried out with pyrolysis-GC-MS and thermally assisted hydrolysis /methylation (THM)-GC-MS (75). The objectives of this project were to use XPS to qualitatively determine the surface elemental composition of the black residue semiquantitatively characterize the surface, for comparison with other surface-related materials and examine the relationship between the chemistry and depth by using Ar+ sputtering. This, then, will aid in validating the radiocarbon date obtained through plasma-chemical oxidation and accelerator mass spectrometry by Steelman et al. (5). 

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