Physicochemical measurements

Conder, J.R. and Young, C.L., Physicochemical Measurements by Gas Chromatography. Wiley, New York, 1979. 

The position of the equilibrium is determined not only by ring size and polar and steric factors but also by the environment of the molecule. The experimental evidence for the existence of three tautomeric forms has been based on the study of their reactivity and, to a lesser degree, on physicochemical measurements 175-177). Often the existence of the corresponding carbinolamine or its acyclic tautomeric form in addition to the basic dehydrated form is quite important. 

The real Willamson synthesis with metallic sodium and sodium chloroacetate is only used for the preparation of pure ether carboxylates for analysis purposes or to obtain physicochemical measurements [229]. 

Lombardo F, Obach RS, Shalaeva MY and Gao F. Prediction of volume of distribution values in humans for neutral and basic drugs using physicochemical measurements and plasma protein binding data. J Med Chem 2002 45 2867-76. 

As in CljSn—P(CMe3)3 the metal-coordinated 39 may be interpreted as an ylide-type compound. Reactions and physicochemical measurements indicate that the phosphane acts as a simple donor130>. 

Decomposition of the primary products of lipid oxidation generates a complex mixture including saturated and unsaturated aldehydes such as hexanal. Hexanal is the most commonly measured end product of lipid oxidation, and both sensory and physicochemical methods are used for its determination. Where other antioxidant activity tests may be nonspecific, physicochemical measurement of hexanal offers the advantage of analyzing a single, well-defined end product. 

The method depended upon the availability of phosphorus oxydichlorofluoride, a compound described by Booth and Dutton,2 who devised an elaborate apparatus for the preparation of the compound in a pure condition for physicochemical measurements. We modified their process to suit the particular needs of this work. The generator which we developed for this step-... 

Locke, D.C. "Physicochemical Measurements Using Chromatography," Adv. Chrom., 14, 87(1976). 

Possible difficulties in obtaining accurate retention data for physicochemical measurements should be recognized, however. The evaluation of to, the elution time of an "unretained peak (274) is often connected with systematic error and the measurement of the retention time of asymmetrical peaks may not be accurate. Moreover, no satisfactory methods are available for the precise evaluation of the phase ratio in the column. Consequently, the measurement of the equflibrium constant proper is beset with difficulties as discussed in Section VII.B. 

Since VD is a function of relative tissue and plasma binding, it follows that if these measurements could be made in vitro, then the data could be used to predict VD. Furthermore, if tissue binding is driven by physicochemical properties, such as lipophilicity, then it also follows that physicochemical measurements could serve as surrogates for tissue binding propensity. In vitro tissue binding and physicochemical measurements form the basis of in vitro approaches to predict human VD. 

This methodology can be helpful in relating strict quantitative measures of olfactory quality with quantitative physicochemical measures. However, the results for this specific study suggest that the range of molecular structures and olfactory quality are too broad to derive practical information for the rational design of molecules with specific flavor qualities. 

Type B azapentalenes behave as one ring, but aromatic character in systems such as 485 seems to be more localized in the ring that lacks the heteroatom X. The nature of X is important, since sulfur derivatives are the most stable this is probably due to a reduction of angle strain and/or to the participation of -orbitals. Physicochemical measurements, chemical reactivity, and quantum-mechanical calculations show... 

The place of gas chromatography (GC) in chemical analysis has been well established. Recent developments in theory and improvements in technique have made it possible to apply GC to a variety of physicochemical measurements. The advantages of GC over other techniques lie in its accuracy, convenience, specificity, versatility, speed, and ability to use only small quantities of sample. Thus, in recent years, many reviews and hundreds of papers emphasizing nonanalytical applications have appeared. 

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