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Original Articles

Differences in the UV-Spectra of the Hop-Derived cis- and trans-Iso-α-Acids

Diferencias en los Espectros UV de cis- y trans-Iso-Alpha-Ácidos Derivados de Lúpulo

Pages 47-51 | Received 07 Sep 2004, Accepted 29 May 2005, Published online: 01 Feb 2018
 

Abstract

The cis- and trans-iso-α-acids are known to have different UV-absorption spectra. This has implications for the analytical quantification of these compounds (for bitterness control and commercial transaction of isomerized products) because these analyses are very often based on UV-absorption. Here, these differences are rationalized on the basis of differences in the tautomeric ratios of the cis- and trans-iso-α-acids, with these ratios being determined by application of ab initio computational chemistry techniques. While there is a significant amount of computational time required to complete the calculations, this approach makes this complex example of tautomerism amenable to detailed study.

RESUMEN

Se sabe que los cis- y trans-iso-alpha-ácidos tienen diversos espectros de absorción UV. Esto tiene implicaciones en la cuantificación analítica de estos compuestos (en el control de amargura y transacciónes comerciales de productos isomerizados) porque estos análisis a menudo se basan en la absorción UV. Aquí, estas diferencias se racionalizan sobre la base de diferencias en los cocientes tautomericos del cis- y trans-iso-alpha-ácidos, con estos cocientes siendo determinados por la aplicación de técnicas de computo ab initio de química. Mientras que hay una cantidad significativa de tiempo de cómputo requerida para terminar los cálculos, el acercamiento de este ejemplo complejo de tautomerismo hace favorable el estudio detallado.

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