Quartz, absolute configuration

This section discusses some simple chemical reactions which convert a chiral nonracemic compound containing no electron absorption band in an easily accessible spectral range into a derivative with absorption in either the visible or quartz ultraviolet region. This is a useful operation if a reliable correlation exists between absolute configuration (conformation) and chiroptical properties. A collection of useful chromophoric systems is found in reference 167. 

De Vries, A. Determination of the absolute configuration of a-quartz. Nature (London) 181, 1193 (1958). 

Evaluation of absolute configuration of molecules using data from "Quartz-catalysis ... 

As found by Schwab et al. metal-ri-quartz catalysts preferentially adsorb and decompose (i )-(-)-butan-2-ol and the remaining unreacted butanol has the (+)-optical rotation. The strueture of quartz eonsists of endless networks of Si02 units forming spatial right- or left-handed helices Using data on adsorption and eatalysis on quartz eiystals the absolute configuration of butan-2-ol can be determined ... 

Condon, Altar, and Eyring came to the conclusion that the absolute configuration of (-)-butan-2-ol has a right-helix" structure if the dehydration of butanol over Cu-quartz catalysts results mainly in ( )-but-2-ene and has a "left-helix" if dehydration results in but-l-ene. This eonelusion followed from the data of Schwab (1934) and is based on the idea that the ehiral structure of the surface of quartz eomplements the reacting molecule of butan-2-ol. 

Errors in thermopower measurements can arise from several sources. The main source of error in this experimental configuration was an approximately lOZ uncertainty in the temperature difference AT across the samples due to uneven heating of the quartz blocks. For temperatures above 9IK, values of the samples absolute thermopower may be off by as much as 0.25 pV/K,... 

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