Hydrogen Fluoride

Abstract

[7664-39-3] FH (MW 20.01) InChI = 1S/FH/h1H InChIKey = KRHYYFGTRYWZRS-UHFFFAOYSA-N (strong Brønsted–Lowry acid2 capable of fluorinating numerous organic substrates;1 cleaves silyl3 and peptide4 protecting groups; effects lignocellulose solvolysis;5 catalyzes a number of electrophilic aromatic substitution reactions6) Alternate Name: Hydrofluoric Acid Physical Data: mp −83.37 °C; bp 19.54 °C; d 1.015 g cm−3 (0 °C), 0.958 g cm−3 (25 °C). Solubility: sol water (52.7 wt %, 6 theoretical plates); strong proton donor to alcohols, carboxylic acids, ethers, and ketones (unstable); insol aliphatic hydrocarbons; very slightly sol aromatic hydrocarbons. Form Supplied in: anhydrous liquid; 48–50% aqueous solution; most common impurity is fluorosilicic acid (<100 ppm). Purification: for virtually all synthetic purposes, anhydrous hydrogen fluoride (AHF) is supplied in sufficiently high purity from commercial sources. Ultrapure AHF can be obtained by either distillation7 of commercially available AHF or thermal decomposition8 of potassium acid fluoride. Handling, Storage, and Precautions: HF is an extremely toxic material. HF can cause severe damage to the respiratory system and will cause severe burns to tissue, e.g. skin, fingernails, mouth, eyes, etc.; penetration through tissue into bone is possible. If contact with HF occurs, the affected area must be flushed immediately with copious amounts of water for at least 15 min. Immediate medical attention must be sought. Recommended personnel protective equipment includes the use of gloves (neoprene/nitrile/rubber composite), goggles, a face-shield, and an apron while working in a well-ventilated hood, preferably equipped with a HF monitor. AHF is supplied either in lecture bottles or 3 lb metal cylinders; aq HF is supplied in polyethylene bottles. The use of glassware and stainless steel vessels should be avoided when handling either AHF or aq HF.9 For reactions run at ambient temperature and pressure, polyethylene vessels can be employed; copper and iron vessels are also suitable. However, the use of an autoclave constructed of high metallurgy such as Monel or nickel, employing inert atmosphere techniques, is highly recommended.