Document Type

Article

Publication Date

8-2012

Publication Source

Industrial & Engineering Chemistry Research

Abstract

The reaction of an isomeric mixture of the methyl perfluoroalkyl ether, C4F9OCH3 (Novec-7100), in the presence of isopropyl alcohol (IPA) and/or water has been studied by measuring the rate of product formation using an ion-selective electrode (ISE) for fluoride ion, Karl Fisher coulometric titrations for water, and 1H and 19F NMR spectroscopy for product identification and rate studies. The results showed the methyl perfluoroalkyl ether to be very stable with products forming at the rate of ∼1 ppm per year at a laboratory temperature of 20 °C. Measurements over the temperature range of 6° to 100 °C were made on samples aged for periods up to 1.8 years. Density functional theory calculations (DFT, B3LYP/6-31+G(d)) were employed to investigate different reaction pathways and formulate the probable reaction mechanism. The experimental enthalpy (ΔH⧧) and entropy (ΔS⧧) of activation were determined based on several different kinetic measurements. The ΔH⧧ values are in the range of 20–25 kcal/mol and the corresponding ΔS⧧ values range from −32 to −15 cal/(mol K). These are in good agreement with the theoretical values. While the range of ΔH⧧ values does not change appreciatively, the ΔS⧧ values are dependent on the proportion of vapor to liquid involved in the reaction of C4F9OCH3 with IPA so that the more vapor the more negative the ΔS⧧ value.

Inclusive pages

10525–10534

ISBN/ISSN

0888-5885

Document Version

Postprint

Comments

The document available for download is the authors' accepted manuscript, provided in compliance with the publisher's policies on self-archiving.

Some differences may exist between this document and the published version; as such, researchers wishing to quote directly from it are advised to consult the version of record.

Permission documentation is on file.

Publisher

American Chemical Society

Volume

51

Issue

32

Peer Reviewed

yes