Microheterogeneity in binary mixtures of methanol with aliphatic alcohols: ATR-IR/NIR spectroscopic, chemometrics and DFT studies

Władysław Wrzeszcz,Sylwester Mazurek,Roman Szostak,Paweł Tomza,Mirosław Antoni Czarnecki,Michał Kwaśniewicz

doi:10.1039/c6ra04595b

Władysław Wrzeszcz, Sylwester Mazurek + Show 4 more

Open Access

https://doi.org/10.1039/c6ra04595b

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Journal: RSC advances	Publication Date: Jan 1, 2016
Citations: 30	License type: cc-by

Affiliation: University of Wrocław

Abstract

This paper reports ATR-IR and NIR spectroscopic studies on microheterogeneity in binary mixtures of methanol with five short chain aliphatic alcohols: ethanol, 1-propanol, 2-propanol,tert-butanol and cyclopentanol.

Highlights

It is well known that alcohol-water mixtures reveal non-ideal behavior due to the presence of hydrophobic interactions disturbing the structure of liquid water.[1,2,3,4,5,6] As a result, the molecules of water and alcohol form separate clusters predominantly composed of one constituent of the mixture
The inhomogeneity distribution of molecules in the mixtures was characterized by MIR/ NIR excess absorption spectra,[13,14] two-dimensional (2D) correlation analysis,[15,16,17] and chemometric methods like principal component analysis (PCA),[18] evolving factor analysis (EFA)[19] and multivariate curve resolution (MCR).[20,21]
Chemometric and 2D correlation analysis reveal the presence of three kinds of clusters in most of the studied mixtures: two kinds of homoclusters and one kind of heterocluster. The composition of this mixed cluster depends on the composition of the mixture but an average molar ratio is close to 1 : 1. Only for ME/TB mixture, in addition to these three clusters, TB-rich cluster with an average ME : TB molar ratio between 1 : 3 and 1 : 4 was found

Summary

Introduction

It is well known that alcohol-water mixtures reveal non-ideal behavior due to the presence of hydrophobic interactions disturbing the structure of liquid water.[1,2,3,4,5,6] As a result, the molecules of water and alcohol form separate clusters predominantly composed of one constituent of the mixture. Similar spectral pattern was observed by Mello et al in the 2D Raman asynchronous spectra of ME/ET mixture.[12] From this splitting the authors assumed the presence of separate ME and ET clusters without hydrogen bonding between different alcohol species.

Results

Conclusion