2,3,4,5-Tetrahydropyridine (Δ¹-piperideine) and its derivatives. Synthesis and chemical properties

Abstract

We study the influence of the tetragonalization occurring during the martensitic phase transition on the exchange interactions in Ni 2 MnGa Heusler alloy using first-principles calculations in conjunction with the frozen-magnon approximation. We show that the tetragonalization alters only the exchange constants characterizing the Mn-Mn interactions. Calculated Curie temperatures within the random-phase approximation are found to agree with experimental data. Moreover, we study the temperature dependence of the magnetization and the small deviation from the experimental data exactly at the temperature of the phase transition is discussed. Obtained results agree with previous theoretical results using Liechtenstein's formula to calculate the exchange constants and the Monte Carlo simulation technique to estimate the Curie temperature.have studied the exchange constants for the stoichiometric Ni 2 MnGa alloys for three values of the c/a ratio (c/a = 0.95, 1 and 1.25) using Liechtenstein's formula [31,32] while Monte Carlo simulations have been employed to estimate a Curie temperature of 375 K for the cubic austenitic phase [33]. Recently, the same group of authors have studied the exchange constants for the off-stoichiometric alloys both in the austenitic and martensitic phases [34,35], while Ghosh and Sanyal have focused only in the austenitic phase [36].

Possible Ribose Synthesis in Carbonaceous Planetesimals

“…The aromatic vitamin B3 derivatives 10-13 have enhanced thermodynamic stability [94] compared to the non-aromatized quinolinic acid derivatives 6-9, whose piperideine ring is highly reactive. [95] Therefore, the final non-aromatized quinolinic acid derivative 9 might be less stable and more likely to decompose to other organics than vitamin B3 13. Some planetesimals, which have the right balance of a big enough size ≳ 10 km and late enough time of formation ≳ 2.5 Myr, can maintain aqueous conditions in their porous interiors for hundreds of thousands to millions of years.…”

Prebiotic Vitamin B3 Synthesis in Carbonaceous Planetesimals

“…In the potential absence of free oxygen in carbonaceous planetesimals, the synthesis of vitamin B 3 in its aromatized form might even be favored over quinolinic acid (following Scheme 1). The aromatic vitamin B 3 derivatives 10–13 have enhanced thermodynamic stability [94] compared to the non‐aromatized quinolinic acid derivatives 6–9 , whose piperideine ring is highly reactive [95] . Therefore, the final non‐aromatized quinolinic acid derivative 9 might be less stable and more likely to decompose to other organics than vitamin B 3 13 .…”

“…The aromatic vitamin B 3 derivatives 10-13 have enhanced thermodynamic stability [94] compared to the nonaromatized quinolinic acid derivatives 6-9, whose piperideine ring is highly reactive. [95] Therefore, the final non-aromatized quinolinic acid derivative 9 might be less stable and more likely to decompose to other organics than vitamin B 3 13. Some planetesimals, which have the right balance of a big enough size 10 km and late enough time of formation 2:5 Myr, can maintain aqueous conditions in their porous interiors for hundreds of thousands to millions of years.…”

An Efficient One‐Step Synthesis of Piperidin‐2‐yl and Pyrrolidin‐2‐yl Flavonoid Alkaloids through Phenolic Mannich Reactions

“…Chrysin (7a) and Δ 1 -piperideine (3,4,5,6-tetrahydropyridine, 8a) [8] were used as representative substrates in our initial survey of reaction conditions (Table 1). In DMF, a dipolar aprotic solvent, at 80°C, the conversion was low and the reaction gave an equimolar mixture of separable C-6/C-8 regioisomers (Table 1, Entry 1).…”