Substituted six-membered ring carbenes: the effects of amino and cyclopropyl groups through DFT calculations

DFT calculations are employed to compare and contrast six-membered ring carbenes including 1,3-dimethyltetrahydropyrimidin-2-ylidene (1a), 1-methyl-3-cyclopropyltetrahydropyridine-2-ylidene (2a), and 1,3-dicyclopropylcyclohexane-2-ylidene (3a) as well as their unsaturated analogues 1b, 2b, 3b, and 2c. The amino groups exert singlet-triplet energy separation (?E_s−t) of 60.9 kcal/mol to 1a while cyclopropyls induce a ?E_s−t of 14.8 kcal/mol to 3a. The simultaneous presence of amino and cyclopropyl in 2a leads to a ?E_s−t of 43.3 kcal/mol. Unsaturation slightly increases the ?E_s−t of 1a and 3a but not that of 2a. Our thermodynamic, kinetic, and reactivity results are compared with those of synthetic five-membered ring N-heterocyclic carbenes.     

Novel four-component route to the synthesis of spiro[indoline-3,4′-pyridine]-3′-carboxylate derivatives

An effective route to spiro[indoline-3,4′-pyridine]-3′-carboxylate derivatives is described. This involves reaction of isatin, 1-phenyl-2-(1,1,1-triphenyl-λ⁵-phosphanylidene)-1-ethanone, and benzylamine derivatives or aliphatic amines in the presence of alkyl acetoacetate (1,3-dicarbonyl compounds) in dry methanol under reflux conditions. The reactive 1:1 enaminone, which is obtained from the addition of the amine to 1,3-dicarbonyl compound, adds to the α,β-unsaturated ketone, which is formed from the reaction of isatin and 1-phenyl-2-(1,1,1-triphenyl-λ⁵-phosphanylidene)-1-ethanone, to produce the alkyl 1′-benzyl-2′-methyl-2-oxo-6′-phenyl-1′H-spiro[indoline-3,4′-pyridine]-3′-carboxylate derivatives in excellent yields.     

Naphthalimide based disperse dyes for nylon 6 and polyester (pet) fibers: Synthesis and evaluation of technical properties in the presence of urea

Technical properties of two naphthalimide based disperse dyes on nylon 6 and polyester fibers were investigated in the presence of urea.The two naphthalimide based disperse dyes were synthesized.The dyes were purified and then fully characterized using ~1H-NMR,FTIR and melting point analysis.Dispersion of the dyes was prepared in water and applied on nylon 6 and PET fibers.The dyes offered good build-up properties on the substrates.In order to increase dye adsorption of the substrates,urea was added into...     

Structural, theoretical and multinuclear NMR study of mercury(II) complexes with a new ambidentate phosphorus ylide

The reaction of the new ambidentate ylide, Ph₃PCHCOCH₂COOC₂H₅ (EAPPY), with HgX₂ (X = Cl, Br and I) in equimolar ratios using methanol as the solvent leads to binuclear complexes of the type [EAPPY·HgX₂]₂ (X = Cl (1), Br (2) and I (3)). Single crystal X-ray analysis reveals the presence of a centrosymmetric dimeric structure containing the ylide and HgX₂ (X = Br or I)_. The IR and NMR data of the product [(EAPPY)·HgCl₂]₂ (1), formed by the reaction of mercury(II) chloride with the same ylide, are similar to those of 2 and 3. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products. Theoretical studies indicate that the nature of the R group in ylides of the type Ph₃PCHCOR has a weak effect on the Hg-C(ylide) bond length in binuclear Hg₂L₂I₄ complexes.     

Chemisorption of NH3 at the open ends of boron nitride nanotubes: a DFT study

Considering the thermodynamic aspects and reaction pathways of chemical adsorption of NH₃ molecule at the open ends of boron nitride nanotubes (BNNTs), theoretically, it was found that the open-ended BNNTs are able to cleave the N–H bond of NH₃ via a one- or two-stepwise mechanism. The N-enriched and B-enriched open-ended BNNTs show a nucleophilic and electrophilic behavior toward the NH₃, respectively. Besides, some effects of this chemical adsorption on the electronic properties of BNNTs were explored.     

Compact right multipliers on a Banach algebra related to locally compact semigroups

For a locally compact semigroup \({\mathcal{S}}\), let \(L_{0}^{\infty}({\mathcal{S}},M_{a}({\mathcal{S}}))\) be the Banach space of all μ-measurable (\(\mu\in M_{a}({\mathcal{S}})\)) functions vanishing at infinity, where \(M_{a}({\mathcal{S}})\) denotes the algebra of all measures in the measure algebra \(M({\mathcal{S}})\) of \({\mathcal{S}}\) with continuous translations. Here, we study right compact multipliers on the Banach algebra \(L_{0}^{\infty}({\mathcal{S}},M_{a}({\mathcal{S}}))^{*}\) equipped with an Arens product.     

Relative T -Injective Modules and Relative T -Flat Modules

Let T be a Wakamatsu tilting module. A module M is called (n, T)-copure injective (resp. (n, T)-copure flat) if ɛ _T ¹ (N, M) = 0 (resp. Γ₁ ^T (N, M) = 0) for any module N with T-injective dimension at most n (see Definition 2.2). In this paper, it is shown that M is (n, T)-copure injective if and only if M is the kernel of an I _n (T)-precover f: A → B with A ∈ Prod T. Also, some results on Prod T-syzygies are presented. For instance, it is shown that every nth Prod T-syzygy of every module, generated by T, is (n, T)-copure injective.     

Synthesis of Dialkyl 2‐(Alkylamino)‐4,9‐dihydro‐9‐oxocyclohepta[b]pyran‐3,4‐dicarboxylates

Dialkyl 2‐(alkylamino)‐4,9‐dihydro‐9‐oxocyclohepta[b]pyran‐3,4‐dicarboxylates are prepared in a one‐pot three‐component reaction of alkyl isocyanide, dialkyl acetylenedicarboxylate, and α‐tropolone (=2‐hydroxycyclohepta‐2,4,6‐trienone). The reaction proceeds smoothly at room temperature and under neutral conditions to afford tropolone derivatives in high yield.     

Nonlinear vibration mitigation of a flexible rotor shaft carrying a longitudinally dispositioned unbalanced rigid disc

Nonlinear Dynamics - This study is dedicated to investigate the nonlinear dynamics of a system composed of a flexible rotor shaft carrying a longitudinally dispositioned unbalanced rigid disc. The...