Experimental and Theoretical Mechanistic Study on the Thermal Decomposition of 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline

Abstract

The present paper is a continuation of comprehensive study regarding to synthesis and properties of pyrazoles and their derivatives. In its framework an experimental and theoretical studies of thermal decomposition of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline were performed. It was found, that the decompositions of the mentioned pyrazoline system in the solution and at the melted state proceed via completely different molecular mechanisms. These mechanisms have been explained in the framework of the Molecular Electron Density Theory (MEDT) with the computational level of B3LYP/6-31G(d). A Bonding Evolution Theory (BET) examination of dehydrochlorination of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline permits elucidation of the molecular mechanism. It was found, that on the contrary for most known HCl extrusion processes in solution, this reaction is realised via single-step mechanism.

The First Examples of [3+2] Cycloadditions with the Participation of (E)-3,3,3-Tribromo-1-Nitroprop-1-Ene

“…So, TMH substituted conjugated nitroalkenes attract the attention of various research centers. In particular, 3,3,3-trichloro-1-nitroprop-1-ene was recently intensively tested as a component of different type cycloadditions involving diazocompounds [ 8 , 9 ], nitrile N -oxides [ 10 ], and especially nitrones [ 11 , 12 , 13 , 14 ]. Regarding 3,3,3-trifluor-1-nitroprop-1-ene, many interesting scientific works are also available at the present time [ 4 , 5 , 6 , 15 , 16 ].…”

The Participation of 3,3,3-Trichloro-1-nitroprop-1-ene in the [3 + 2] Cycloaddition Reaction with Selected Nitrile N-Oxides in the Light of the Experimental and MEDT Quantum Chemical Study

“…The synthesis of these type of compounds is relatively easy using the corresponding 3,3,3-trihalo-1-nitroprop-1-enes as precursors. In the literature, some examples of the application of 3,3,3-trichloro-1-nitroprop-1-ene (TNP) as component of cycloaddition processes are available [24,25].…”

“…In other cases, the presence of the CCl 3 group is not enough to stabilize the corresponding cycloadduct. For instance, diaryldiazomethanes react with TNP yielding unstable 5-nitropyrazoline systems, which surprisingly converted very fast into the corresponding 4-dimethylvinylpyrazolines via hydrochloride extrusion (Scheme 3) [24,25]. It should be underlined at this point that the HCl extrusion from molecular systems including the CCl 3 group is very rare and was unobserved earlier in five-membered heterocycles.…”

A DFT Study on the Molecular Mechanism of Additions of Electrophilic and Nucleophilic Carbenes to Non-Enolizable Cycloaliphatic Thioketones

“…For the simulation of the reactions paths, the wb97xd functional included in the GAUSSIAN 09 package [48] and the 6-311g(d,p) basis set [49,50] including both diffuse and polarization functions for all relevant atoms was used. A similar theory level has been commonly used for the mechanistic research aspects of cycloaddition reactions [28,39,[51][52][53][54][55]. All localised stationary points have been characterized using vibrational analysis.…”