# Infrared Absorption Spectra of Monohydric Alcohols

Authors: Irina Doroshenko; Valeriy Pogorelov; Valdas Sablinskas
Journal: Dataset Papers in Chemistry
 (2013)

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## Abstract

FTIR spectra of homologous series of monohydric alcohols which belong to the class of partly ordered liquids were registered. The molecules of monohydric alcohols containing hydroxyl group are able to form hydrogen-bonded clusters in the condensed phase. The existence of clusters is clearly observed from the position and the contour of the stretch OH band in the vibrational spectra of liquid alcohols. In this work, the experimentally registered FTIR spectra of liquidn-alcohols from methanol to decanol are presented as well as the same spectra of methanol, ethanol, propanol, butanol, pentanol, and hexanol in gas phase.


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## Body

## 1. Introduction

The clustering phenomena and structural peculiarities of partly ordered liquids are of great interest in the scientific community. This interest is even growing in context of recent trends and developments in studies on modern multifunctional materials, heterogeneous systems, and nanotechnologies. Among such partly ordered liquids are monohydric alcohols that usually build broad variety of H-bond aggregates. They are quite simple and convenient models to investigate properties of molecular systems sized over the mesoscopic scale (~1–100 nm).The cause of cluster formation in alcohols is the intermolecular hydrogen bond. The vibrational spectra of liquid alcohols differ from their spectra in gas phase or in matrix by the absence of the vibrational band of free hydroxyl group vibrations. Instead of this, the red-shifted diffuse band, which is usually associated with the presence of molecular aggregations (clustering), is observed. However the mechanism of the diffuse band formation and its structure are still the unsolved problems. The importance of the problems connected with the alcohol clustering and structure and, in particular, with the mechanisms of the diffuse absorption band formation is reflected in the great number of experimental [1–9], theoretical [10–14], and combined works [15–19] published in the recent years.The properties of a great number of partly ordered liquids are determined mainly by the characteristics of the hydrogen bond network. Monohydric alcohols are the convenient objects for the investigation of such intermolecular interaction as hydrogen bond. In this work, we present the experimentally registered FTIR spectra of the homologous series of monohydric alcohols in liquid and gaseous states.


## 2. Methodology

The experimental registration of the presented spectra was made in the laboratory of Fourier transform infrared absorption spectroscopy at the Physics Department of Vilnius University, Lithuania. All spectra were registered using Bruker’s FTIR spectrometer VERTEX 70 in the spectral range from 750 to 4000 cm−1. In order to increase signal-to-noise ratio, each spectrum was taken as an average of 128 scans. Liquid-phase samples of the monohydric alcohols with purity >99.9 from Fluka were used as received. Gas-phase samples were obtained by the natural evaporation in vacuum process from the liquid surface.Spectra of liquidn-alcohols were registered by attenuated total reflection (ATR) method at the resolution 4 cm−1. The spectrometer was equipped with liquid-N2-cooled mercury cadmium telluride (MCT) detector. Blackman-Harris 3-term apodization function and zero filling 2 were used during processing of interferograms. Single-pass ZnSe ATR crystal was used for capturing of the ATR spectra. Angle of incidence of IR beam was set to 70 degree, what insured total reflection from ZnSe-alcohol interface for all the title alcohols.Spectra of the alcohols in gaseous state were measured using conventional single-pass 10 cm gas cell equipped with KBr windows with the resolution 0.5 cm−1 using deuterated triglycine sulfate (DTGS) detector. Blackman-Harris 3-term apodization function and zero filling 128 were used during processing of interferograms. Pressure of each alcohol was set close to its saturated pressure at 20°C: 13 mbar for methanol, 5.5 mbar for ethanol, 2 mbar for 1-propanol, 0.7 mbar for 1-butanol, 0.2 mbar for 1-pentanol, and 0.1 mbar for 1-hexanol.The gas cell was filled with an alcohol using standard vacuum technique. Atmospheric oxygen and nitrogen were removed from the alcohols by five freeze-pump-thaw cycles.In this paper, the experimentally registered Fourier transform infrared absorption (FTIR) spectra of the first ten members of the homologous series of monohydric alcohols with the linear structure of the molecule CH3–(CH2)n–OH, n = 0–9, in liquid phase are presented.The registered by authors at room temperature FTIR spectra of liquid methanol (CH3OH), ethanol (C2H5OH), propanol (C3H7OH), butanol (C4H9OH), pentanol (C5H11OH), hexanol (C6H12OH), heptanol (C7H15OH), octanol (C8H17OH), nonanol (C7H15OH), and decanol (C10H21OH) are presented in Figures 1–10, respectively. The recorded by authors FTIR spectra of gaseous alcohols at room temperature (methanol, ethanol, propanol, butanol, pentanol, and hexanol) are presented in Figures 11–16, respectively.Figure 1
FTIR spectrum of liquid methanol CH3OH.Figure 2
FTIR spectrum of liquid ethanol C2H5OH.Figure 3
FTIR spectrum of liquid propanol C3H7OH.Figure 4
FTIR spectrum of liquid butanol C4H9OH.Figure 5
FTIR spectrum of liquid pentanol C5H11OH.Figure 6
FTIR spectrum of liquid hexanol C6H13OH.Figure 7
FTIR spectrum of liquid heptanol C7H15OH.Figure 8
FTIR spectrum of liquid octanol C8H17OH.Figure 9
FTIR spectrum of liquid nonanol C9H519H.Figure 10
FTIR spectrum of liquid decanol C10H21OH.Figure 11
FTIR spectrum of gaseous methanol.Figure 12
FTIR spectrum of gaseous ethanol.Figure 13
FTIR spectrum of gaseous propanol.Figure 14
FTIR spectrum of gaseous butanol.Figure 15
FTIR spectrum of gaseous pentanol.Figure 16
FTIR spectrum of gaseous hexanol.


## 3. Dataset Description

The dataset associated with this Dataset Paper consists of 16 items which are described as follows.1
FTIR spectrum of liquid methanol CH3OH (Figure 1). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).2
FTIR spectrum of liquid ethanol C2H5OH (Figure 2). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).3
FTIR spectrum of liquid propanol C3H7OH (Figure 3). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).4
FTIR spectrum of liquid butanol C4H9OH (Figure 4). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).5
FTIR spectrum of liquid pentanol C5H11OH (Figure 5). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).6
FTIR spectrum of liquid hexanol C6H13OH (Figure 6). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).7
FTIR spectrum of liquid heptanol C7H15OH (Figure 7). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).8
FTIR spectrum of liquid octanol C8H17OH (Figure 8). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).9
FTIR spectrum of liquid nonanol C9H519H (Figure 9). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).10
FTIR spectrum of liquid decanol C10H21OH (Figure 10). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).11
FTIR spectrum of gaseous methanol CH3OH (Figure 11). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).12
FTIR spectrum of gaseous ethanol C2H5OH (Figure 12). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).13
FTIR spectrum of gaseous propanol C3H7OH (Figure 13). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).14
FTIR spectrum of gaseous butanol C4H9OH (Figure 14). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).15
FTIR spectrum of gaseous pentanol C5H11OH (Figure 15). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).16
FTIR spectrum of gaseous hexanol C6H13OH (Figure 16). FTIR spectrum is the dependence of the infrared absorbance (measured in arbitrary units (a.u.)) on the wavenumber (measured in the reversed centimeters (cm−1)).


## 4. Concluding Remarks

In this work, the experimentally registered IR absorption spectra of monohydric alcohols in liquid and gaseous state are presented. The collected experimental data can be useful for the investigations of the structure and properties of partly ordered liquids, dynamics and kinetics of cluster formation processes in hydrogen-bonded systems, peculiarities of phase transitions from gas to liquid in such objects, and so forth.



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*Source: 329406-2012-10-24.xml*