Full Kinetics and Mechanism Investigation for Generating 4-Substituted 1, 4- Dihydropyridine Derivatives in the Presence of Green Catalyst and Aqueous Medium: Experimental Procedure.

Aims And Objective: The main objective of the kinetic investigation of the reaction between ethyl acetoacetate 1, ammoniumacetat 2, dimedone 3, and diverse substitutions of benzaldehyde 4-X, (X= H, NO, CN, CF, Cl, CH (CH), CH, OCH, OCH, and OH) for generating 4-substituted 1, 4-dihydropyridine derivatives (product 5) was to recognize the most realistic reaction mechanism. The layout of the reaction mechanism was studied kinetically via a UV-visible spectrophotometry approach.

Materials And Methods: Among the various mechanisms, only mechanism1 (path1) involving 12 steps was recognized as a dominant mechanism (path).

Synthesis and Kinetics of Highly Substituted Piperidines in the Presence of Tartaric Acid as a Catalyst.

Aim & Scope: The synthesis of highly substituted piperidine from the one-pot reaction between aromatic aldehydes, anilines and β-ketoesters in the presence of tartaric acid as a catalyst has been investigated in both methanol and ethanol media at ambient temperature. Different conditions of temperature and solvent were employed for calculating the thermodynamic parameters and obtaining an experimental approach to the kinetics and mechanism. Experiments were carried out under different temperature and solvent conditions.

Structural effects on kinetics and a mechanistic investigation of the reaction between DMAD and N-H heterocyclic compound in the presence of triphenylarsine: spectrophotometry approach.

Kinetics and a mechanistic investigation of the reaction between dimethyl acetylenedicarboxcylate (DMAD) and saccharin (N-H heterocyclic compound) has been spectrally studied in methanol environment in the presence of triphenylarsine (TPA) as a catalyst. Previously, in a similar reaction, triphenylphosphine (TTP) (instead of triphenylarsine) has been employed as a third reactant (not catalyst) for the generation of an ylide (final product) while, in the present work the titled reaction in the presence of TPA leaded to the especial N-vinyl heterocyclic compound with different kinetics and mechanism. The reaction followed second order kinetics.

Kinetic Spectrophotometric Method for the 1,4-Diionic Organophosphorus Formation in the Presence of Meldrum's Acid: Stopped-Flow Approach.

The kinetics of the reaction between triphenylphosphine (TPP) and dimethyl acetylenedicarboxylate (DMAD) in the presence of Meldrum's acid (MA) for the generation of the 1,4-diionic organophosphorus compound has been investigated using the stopped-flow and UV-VIS spectrophotometry techniques. The first step of the reaction between TPP and DMAD for the generation of (I₁) in ethanol was followed by the stopped-flow apparatus. This step was recognized as a fast step.

Caffeine Catalyzed Synthesis of Tetrahydrobenzo[b]pyran Derivatives: Synthesis and Insight into Kinetics and Mechanism.

Aim And Objective: Tetrahydrobenzo[b]pyran derivatives are considered as a special class in drug research because of their various biological and pharmacological benefiting usages. In the current work, we developed new synthetic methods for the preperation of tetrahydrobenzo[b]pyran derivatives using arylaldehydes 1, malononitrile 2 and dimedonein 3 in the presence of caffeine as catalyst as a cheap, easily accessible, biodegradable and green catalyst. Moreover, for the first time, we have described kinetic results together along with detailed mechanistic studies of the synthetic reaction of a derivative of 4Htetrahydrobenzo[ b]pyran based on a global kinetic analysis methodology using UVvis spectrophotometry apparatus.

Theoretical study of inhibition efficiencies of some amino acids on corrosion of carbon steel in acidic media: green corrosion inhibitors.

Inhibition efficiencies of three amino acids [tryptophan (B), tyrosine (c), and serine (A)] have been studied as green corrosion inhibitors on corrosion of carbon steel using density functional theory (DFT) method in gas and aqueous phases. Quantum chemical parameters such as EH OMO (highest occupied molecular orbital energy), E LUMO (lowest unoccupied molecular orbital energy), hardness (η), polarizability ([Formula: see text]), total negative charges on atoms (TNC), molecular volume (MV) and total energy (TE) have been calculated at the B3LYP level of theory with 6-311++G** basis set. Consistent with experimental data, theoretical results showed that the order of inhibition efficiency is tryptophan (B) > tyrosine (C) > serine (A).

Dynamic ¹H NMR studies of hindered internal rotations in the synthesized particular phosphorus ylide: experimental and theoretical approaches.

Dynamic (1)H NMR measurements were performed within the synthesized particular phosphorus ylide involving 4-formylphenyl phenylcarbamate. Four rotational process and thereby parameters were targeted for rotation around the CC, C-C, HCNC and OCNC bonds. The Gibbs free activation energy in CDCl3, ΔG(≠)exp, was found to be 64 ± 2, 50 ± 2, 41 ± 2 and 63 ± 2, respectively.

One-pot diastreoselective synthesis of highly functionalized cyclohexenones: 2-oxo-N,4,6-triarylcyclohex-3-enecarboxamides.

A series of 2-oxo-N,4,6-triarylcyclohex-3-enecarboxamides were synthesized by condensing acetophenone and aromatic aldehydes with acetoacetanilide in ethanol in the presence of 2-hydroxyethylammonium acetate (2-HEAA) as a basic ionic liquid at ambient conditions. This process is simple, efficient and environmentally benign and proceeds in high yield, short reaction times and there is no need for column chromatography purification.

Full kinetics investigation of the formation reaction of phosphonate esters in the gas-phase: a theoretical study.

In the present work, the proposed multiple-mechanisms have been investigated theoretically for the reaction between triphenyl phosphite and dimethyl acetylenedicarboxylate in the presence of N-H acid such as aniline for generation of phosphonate esters using ab initio molecular orbital theory in gas phase. The profile of the potential energy surface was constructed at the HF/6-311G(d,p) level of theory. The kinetics of the gas phase reaction was studied by evaluating the reaction path of various mechanisms.

A joint experimental and theoretical investigation of kinetics and mechanistic study in a synthesis reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of benzhydrazide.

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine (TPP) and dialkyl acetylenedicarboxylates, in the presence of NH-acids, such as benzhydrazide. To determine the kinetic parameters of the reactions, they were monitored by UV spectrophotometery. The second order fits were automatically drawn and the values of the second order rate constant (k(2)) were calculated using standard equations within the program.

Dynamic 1H NMR study around the carbon-carbon single bond and partial carbon-carbon double bond in the two particular phosphorus ylides and in an enaminoester.

Herein, a series of separate dynamic (1)H NMR effects are reported at different temperatures within a particular enaminoester involving a phenanthridine. These effects are attributed to restricted rotation around the two single bonds such as carbon-carbon (H(a)-C-C-H(b)) and nitrogen-carbon (NCCOOCH(3)). Activation energies (E(a)) for these interconversion processes in their rotational isomers are equal to 20 and 20 ± 1 kJ mol(-1), respectively.

Establishing a new conductance stopped-flow apparatus to investigate the initial fast step of reaction between 1,1,1-trichloro-3-methyl-3-phospholene and methanol under a dry inert atmosphere.

In the present work, for the first time, investigation of the initial fast step of reaction between 1,1,1-trichloro-3-methyl-3-phospholene (TCMP) and methanol was studied under a dry inert atmosphere by a newly constructed CSF apparatus by means of a further development in the configuration of the previous stopped-flow spectrophotometer (SFS). Hence, it was necessary to make many changes to the stopped-flow apparatus: replacement of the spectrophotometer amplifier with a conductance amplifier and the use of a conductivity cell to replace the optical one. The conductivity cell was made of polyethylene capillary tube (1 mm internal diameter; i.

Synthesis of 5-aryl-1,3-dimethyl-6-(alkyl- or aryl-amino) furo [2,3-d]pyrimidine derivatives by reaction between isocyanides and pyridinecarbaldehydes in the presence of 1,3-dimethylbarbituric acid.

5-Aryl-6-(alkyl- or aryl-amino)-1,3-dimethylfuro [2,3-d]pyrimidine derivatives were obtained by in situ reaction alkyl or aryl isocyanides and pyridinecarbaldehyde derivatives in the presence of 1,3-dimethylbarbituric acid in dichloromethane without any prior activation or modifications.

Synthesis of cyano-2,3-dihydropyrrolo[1,2-f]phenanthridine derivatives via a domino-Knoevenagel-cyclization.

In a new multicomponent reaction phenanthridine reacts with isocyanides and malonitrile in the presence of benzaldehyde derivatives to produce 2-aryl-3-(alkyl- or arylimino)-2,3-dihydropyrrolo[1,2-f]phenanthridine-1,1(12b H)-dicarbonitrile in a simple, mild, and efficient protocol in excellent yields.

Novel multicomponent reactions involving isoquinoline or phenanthridine and activated acetylenic ester in the presence of heterocyclic NH or 1,3-dicarbonyl compounds.

Multicomponent reactions involving azines (phenanthridine or isoquinoline) and dimethyl acetylenedicarboxylate were undertaken in the presence of heterocyclic NH compounds (indole, 2-methyl indole, 3-methyl indole, carbazole and 3,6-dibromocarbazole) or 1,3-dicarbonyl compounds such as N,N'-dimethylbarbituric acid, 1,3-diethyl-2-thiobarbituric acid, acetylacetone, 1,3-diphenyl-1,3-propandione and cyclopentan-1,3-dione to generate enaminoesters in good yields.

Synthesis of oxime phosphoranes from reaction between triphenylphosphine and acetylenic esters in the presence of oxime derivatives.

A new one-pot, simple and effective procedure is presented for the preparation of O-containing phosphorus ylides by the Michael addition reaction of N-methylpyrrole-2-carbaldehydoxime, pyridin-2-carbaldehydoxime or acetophenonoxime with acetylenic esters.