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Hydrogen fluoride is an excellent solvent. Reflecting the ability of HF to participate in hydrogen bonding, even proteins and carbohydrates dissolve in HF and can be recovered from it. In contrast, most non-fluoride inorganic chemicals react with HF rather than dissolving. [17]
Hydrogen bonding amongst HF molecules gives rise to high viscosity in the liquid phase and lower than expected pressure in the gas phase. Hydrogen fluoride does not boil until 20 °C in contrast to the heavier hydrogen halides which boil between −85 °C and −35 °C (−120 °F and –30 °F).
Unlike other hydrohalic acids, such as hydrochloric acid, hydrogen fluoride is only a weak acid in dilute aqueous solution. [18] This is in part a result of the strength of the hydrogen–fluorine bond, but also of other factors such as the tendency of HF, H 2 O, and F − anions to form clusters. [19]
This neutralization reaction forms hydrogen fluoride (HF), the conjugate acid of fluoride. In aqueous solution, fluoride has a pK b value of 10.8. It is therefore a weak base, and tends to remain as the fluoride ion rather than generating a substantial amount of hydrogen fluoride. That is, the following equilibrium favours the left-hand side in ...
[6] hydrogen fluoride catalyses disproportionation to sulfur and sulfur tetrafluoride by forming a reactive intermediate HSF molecule. [7] When FSSF 3 dissociates, the F cis atom forms a new bond to the S top atom, and the S-S bond breaks. [3] As a gas, at ambient and totally clean conditions, FSSF 3 decomposes with a half life of about 10 hours.
However, chlorine can also have oxidation states from +1 to +7 and can form more than one bond by donating valence electrons. Hydrogen has only one valence electron, but it can form bonds with more than one atom. In the bifluoride ion ([HF 2] −), for example, it forms a three-center four-electron bond with two fluoride atoms: [F−H F − ↔ ...
H-bonds can also be measured by IR vibrational mode shifts of the acceptor. The amide I mode of backbone carbonyls in α-helices shifts to lower frequencies when they form H-bonds with side-chain hydroxyl groups. [27] The dynamics of hydrogen bond structures in water can be probed by this OH stretching vibration. [28]
The Simons process, named after Joseph H. Simons entails electrolysis of a solution of an organic compound in a solution of hydrogen fluoride. An individual reaction can be described as: R 3 C–H + HF → R 3 C–F + H 2. In the course of a typical synthesis, this reaction occurs once for each C–H bond in the precursor.