Mulling oils

Note IR absorption can depend on whether mull or solvent is used 

The transmission ranges of various window materials are listed in Table 12.2. 

Nujol (a high-molecular-weight hydrocarbon) can be used from 650 cm to the far infrared. It gives IR absorptions around 2900 (vs), 1460, and 1350 cm-. Fluorolube (a high-molecular-weight fluorinated hydrocarbon) is useful for the range 4000 to 1370 cm . Hexachlorobutadiene can also be used. 

Organic Chemist s Desk Reference, Second Edition 

The following solvents are commonly used to record IR spectra. They cannot be used in the regions shown (cm ). 

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When only very small samples are available, ultra-microcavity cells are used in conjunction with a beam condenser. A spectrum can be obtained on a few micrograms of sample in solution. When volatility permits, the solute can be recovered for examination by other spectrometric techniques. The absorption patterns of selected solvents and mulling oils are presented in Appendix A. 

CHART AND SPECTRAL PRESENTATIONS OF ORGANIC SOLVENTS, MULLING OILS, AND OTHER COMMON LABORATORY SUBSTANCES... 

APPENDIX A TRANSPARENT REGIONS OF SOLVENTS AND MULLING OILS... 

The open regions are those in which the solvent transmits more than 25% of the incident light at 1 mm thickness. b The open regions for mulling oils indicate transparency of thin films. 

TabIe-2.7 Infrared Transmission characteristics of selected solvents and Mulling Oils... 

Table-2.7 Infrared Transmission characteristics of selected solvents and Mulling Oils (Transmission below 80% obtained with a 0-10 mm cell path is given in cm ) ...

Chart and Spectral Presentations of Organic Solvents, Mulling Oils, and Other Common Laboratory Substances... 

To reduce scattered light the following methods have been suggested mull oils, fluorocarbons, wax, alkali and ammonium halides, H2O and D2O, and evaporated or sublimed films. 

The advantage of mulls over KBr pellets is that mulls are easier and faster to make since there is no time-consuming pellet pressing involved. Mulls are also well suited to samples that will degrade upon exposure to atmospheric moisture. The mulling oil coats and protects sample particles from the environment, and since the oil is hydrophobic water is effectively repelled. 

Mulling Agent/Mulling Oil Oil that is added to a ground sample for the preparation... 

Split Mulls The technique of using two different mulling oils, namely Nujol and Fluorolube, to obtain two mulls of the same sample. These two oils are transparent in different wavenumber rauges. By splicing the spectra of the two mulls together, a spectrum free of most mulling oil absorbances can be obtained. 

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