6068-67-3Relevant academic research and scientific papers
Microwave and Quantum Chemical Study of Intramolecular Hydrogen Bonding in 2-Propynylhydrazine (HC≡CCH2NHNH2)
M?llendal, Harald,Samdal, Svein,Guillemin, Jean-Claude
, p. 4071 - 4078 (2016)
The microwave spectrum of 2-propynylhydrazine (HC≡CCH2NHNH2) was investigated in the 23-124 GHz spectral interval. The spectra of two conformers denoted I and II were assigned. I is the lower-energy form, and relative intensity measurements yielded an internal energy difference of 3.0(4) kJ/mol between I and II. The spectra of the ground and five vibrationally excited states were assigned for I, whereas only the spectrum of the ground vibrational state was assigned for II. Both I and II are each stabilized simultaneously by two intramolecular hydrogen bonds. The first of these hydrogen bonds is formed between the hydrogen atom of the -NH- part of the hydrazino group, and the second internal hydrogen bond is formed between one of the hydrogen atoms of the -NH2 part. The φ-electrons of the triple bond is thus shared by these two hydrogen atoms. The shortest contact between a hydrogen atom of the hydrazino group and the φ-electrons of the ethynyl group is found in lower-energy conformer I. The conformational properties of 2-propynylhydrazine were explored by MP2/cc-pVTZ and CCSD/cc-pVQZ calculations. The CCSD method predicts that seven rotameric forms exist for this compound. Five of these rotamers are stabilized by internal hydrogen bonding. The simultaneous sharing of the φ-electrons of the triple bond by two hydrogen atoms occurs only in Conformers I and II, which are predicted to be the two forms with the lowest energies, with I 2.52 kJ/mol lower in energy than II. The effective rotational constants of the ground vibrational states of I and II were predicted by a combination of MP2 and CCSD calculations, whereas centrifugal distortion constants and vibration-rotation constants were calculated by the MP2 method. The theoretical spectroscopic constants are compared with the experimental counterparts. It is concluded that more refined calculations are necessary to obtain complete agreement.
N-Propynyl analogs of β-phenylethylidenehydrazines: Synthesis and evaluation of effects on glycine, GABA, and monoamine oxidase
MacKenzie, Erin M.,Fassihi, Afshin,Davood, Asghar,Chen, Qiao-Hong,Rauw, Gillian,Rauw, Gail,Knaus, Edward E.,Baker, Glen B.
experimental part, p. 8254 - 8263 (2009/04/07)
A group of β-phenylethylidenehydrazines possessing a variety of substituents (Me, OMe, Cl, F, and CF3) at the ortho-, meta-, or para-positions of the phenyl ring, in conjunction with either a N-bis-(2-propynyl) or a N-mono-(2-propynyl) moiety, were synthesized and compared to the novel neuroprotective drug β-phenylethylidenehydrazine (PEH) with regard to their ability to inhibit the enzymes GABA-transaminase (GABA-T) and monoamine oxidase (MAO)-A and -B in vitro in brain tissue. Two of the analogs synthesized (mono- and bis-N-propynylPEH) were also studied ex vivo in rats to compare their effects to those of PEH with regard to ability to inhibit GABA-T and MAO and to change brain levels of several important amino acids. Unlike PEH, none of the new drugs inhibited GABA-T in vitro at 10 or 100 μM, and all of the drugs (including PEH) were poor inhibitors (at 10 μM) of MAO-A and -B in vitro. The two analogs studied ex vivo inhibited GABA-T to a lesser extent than PEH, unlike PEH that did not elevate brain levels of GABA, and inhibited MAO-A and -B more potently than PEH. Interestingly, unlike PEH, the two analogs caused marked increases in brain levels of glycine; because of the current interest in drugs that increase glycine availability in the brain as potential antipsychotic drugs, these two analogs now warrant further investigation.
