Supramolecular Reaction between Pressure-Frozen Acetonitrile Phases α and β

Abstract

The balance of weak CH...N bonds involving the H 3C- and -CN groups has been related to the structural rearrangement between centrosymmetric and polar acetonitrile structures. The linear highly polar molecules arrange antiparallel in phase alpha below a freezing temperature of 225 K/0.1 MPa and above a freezing pressure of 0.38(5) GPa/296 K and in a polar mode in phase beta below 206 K/0.1 MPa and at pressures higher than 0.63(5) GPa/296 K. The alpha <--> beta phase transition has been considered as a supramolecular reaction between 2-dimensional and 3-dimensional hydrogen-bonding networks, the latter favoring the polar association. Acetonitrile has been in situ pressure-frozen, and its structure has been determined at room temperature by single-crystal X-ray diffraction at 0.57(5), 0.63(5), and 1.50(5)GPa. The crystallization pressure at 296 K has been determined as 0.38(5) GPa both by ruby fluorescence in a diamond anvil-cell and by the compressibility measurement in a cylinder-and-piston device. Acetonitrile mixed with methanol trimerized at 1.60 GPa and 473 K yielding 4-amino-2,6-dimethylpyrimidine: it was in situ crystallized, and the structure of a single crystal, recovered at ambient conditions, was determined.

Polymerization of Acetonitrile via a Hydrogen Transfer Reaction from CH3 to CN under Extreme Conditions

“…In agreement with the previous work, [11,[13][14][15] the in situ Raman spectra indicate that acetoni- In agreement with the previous work, [11,[13][14][15] the in situ Raman spectra indicate that acetoni-…”

“…Finally, it transforms into a graphitic polymer by eliminating ammonia. In agreement with the previous work, [11,[13][14][15] the in situ Raman spectra indicate that acetoni- It highlights the fact that very inert CÀH can be activated by high pressure, even at room temperature and without a catalyst.…”

Pressure-Induced Phase Transition in Hydrogen-Bonded Supramolecular Adduct Formed by Cyanuric Acid and Melamine

“…Nevertheless, there have been limited reports on structural changes of hydrogen-bonded supramolecular materials under high pressure. 18,19 Recently, we have carried out high-pressure studies on melamine-boric acid adduct (M · 2B) and have shown that M · 2B undergoes a reversible pressure-induced amorphization. 20 Morrison studied temperatureand pressure-induced proton transfers in the hydrogen-bonded adduct formed between squaric acid and bipridine.…”

A Facile Synthesis of New L‐Proline‐Based Trifluoromethyl Oxazole Derivatives Using Microwave Irradiation and Conventional Method

“…After the purification and identification of the product by IR, 1 H‐NMR, 13 C‐NMR, and X‐ray, 2,6‐dimethylpyrimidin‐4‐amine ( 3 ) was obtained as the main product. Under these conditions, in addition to the reaction of imidoyl chlorides 1a with l ‐proline, in the presence of NaH, three molecules of acetonitrile were condensed to produce compound 3 (Scheme ) . The single‐crystal X‐ray analyses confirm the structure of the 2,6‐dimethylpyrimidin‐4‐amine ( 3 ).…”