Rotation measurement

Determined from optical rotation measurements that arc compared with reported values. e Based upon isolated products purified by distillation. 

Marvel, Dec, and Cooke [J. Am. Chem. Soc., 62 (3499), 1940] have used optical rotation measurements to study the kinetics of the polymerization of certain optically active vinyl esters. The change in rotation during the polymerization may be used to determine the reaction order and reaction rate constant. The specific rotation angle in dioxane solution is a linear combination of the contributions of the monomer and of the polymerized mer units. The optical rotation due to each mer unit in the polymer chain is independent of the chain length. The following values of the optical rotation were recorded as a function of time for the polymerization of d-s-butyl a-chloroacrylate... 

When microelectronics and solid state devices developed over the last five to four decades, the development of solid-state sensors followed suit, resulting in the introduction of NTC and PTC resistors to monitor temperature, and first Reed relais and inductive sensors to determine position and distance, or tachometers for rotational measurements in washing machines and dish washers over the past two decades. 

See Section IV.1 for alternative methods of chiral resolution. Partial chemical hydrolysis of proteins and peptides with hot 6 M HC1, followed by enzymatic hydrolysis with pronase, leucine aminopeptidase and peptidyl D-amino acid hydrolase, avoids racemiza-tion of the amino acids281. The problems arising from optical rotation measurements of chiral purity were reviewed. Important considerations are the nonideal dependence of optical rotation on concentration and the effect of chiral impurities282. 

This definition refers to an enantiomeric mixture produced in an asymmetric synthesis. In some cases where a diastereomeric mixture is produced, the definition has to be altered accordingly. Percent optical purity is an operational term that depends on optical rotation measurements. It is not necessarily equal to the percent enantiomeric purity (13), which is a more meaningful term and is the extent to which one enantiomer is formed in excess over the other ... 

Reliance on the use of optical purity as a means of evaluating an asymmetric synthesis may give erroneous results (3). Optical rotation measurements may be sensitive to the presence of impurities. Furthermore, the optical rotation of the pure enantiomer may not be accurately established. Even in the absence of nonenantiomeric impurities, and where the rotation of a single pure enantiomer is known, there are cases where the enantiomeric purity is not equal to the optical purity (19). 

The optical rotation measurements ( ) can be used to determine the amount X of left handed helices present in solution, which is given by ... 

Starting with a sucrose concentration AO = 1.0 millimol/liter and an enzyme concentration Ceo = 0.01 millimol/liter, the following kinetic data are obtained in a batch reactor (concentrations calculated from optical rotation measurements) ... 

Optical rotation measurements were made using the sodium D line at 25°C in a 1 dm cell and the readings obtained were as follows ... 

Enantiomeric Purity (ep) - General measure of the composition of a mixture of enantiomers, to be applied except when the determination is based on optical rotation measurements see Optical Purity. 

As the specific rotation also depends on temperature, the temperature at which the rotation is measured is often shown in the equation. A specific rotation measured at 25 °C is denoted more precisely as... 

Polarimetric detectors have demonstrated significant advantages for identification of optically active drug residues because optical activity is an extremely rare characteristic usually associated with biological activity. Specific rotation measurements on drug residues as they elute from the LC column have the potential to identify closely related structural analogues even when present in a compli-... 

NMR and optical rotation measurement demonstrated that deuterium incorporation on the chiral C-4 in 9-hydroxy-6-methyl-3,4-dihydro-2H-pyrido[2,l-b][l,3]thiazinium-4-carboxylate in 0.4 N sodium hydroxide at 40°C occurred without racemization (73ACS1059). 

Optical rotation measures the degree that light is rotated (see Table Gl.5.7 in Anticipated Results). In citrus oils, d-limonene is the major enantiomer in the sample. Since other optically active compounds are often present in racemic mixtures, there is no net rotation and thus they are ignored. If a compound is a racemic mixture, the polarimeter will not give a reading. Readings can be verified with known standards. 

---