Jae-Goo Shim

Regiospecific synthesis of 2-allylated-5-substituted tetrazoles via palladium-catalyzed reaction of nitriles, trimethylsilyl azide, and allyl acetates

Abstract A variety of 2-allylated-5-substituted tetrazoles were prepared in excellent yields through the reaction of alkyl- and arylidenemalononitriles, allyl acetates and trimethylsilyl azide in the presence of a palladium catalyst.

Solubility of carbon dioxide in aqueous solutions of 2-amino-2-ethyl-1,3-propanediol

This work was supported by Grant 2000-C-CD02-P-01 from the Korea Energy Management Corporation R&D Headquarter and also partially by the Brain Korea 21 Project.

Removal of carbon dioxide by absorption into blended amines: kinetics of absorption into aqueous AMP/HMDA, AMP/MDEA, and AMP/piperazine solutions

The emissions of anthropogenic carbon dioxide (CO2) are believed make a significant impact on global climate change. Hence, amine chemical absorption technology has been suggested to separate and recover CO2. In this study, reaction rate constants between CO2 and blended amines were determined by measuring their absorption rate for CO2. The experiments were carried out to investigate the characteristics of CO2 absorption by using additional absorbents such as hexamethylenediamine (HMDA), N-methyldiethanolamine (MDEA) or piperazine blended into 2-amino-2-methyl-1-propanol (AMP) in an agitated vessel. The absorption rates of CO2 into aqueous blended amine solutions were measured. Additive concentrations of 1, 3, and 5 wt% were added for each 30 wt% AMP solution. The results showed that the addition of HMDA, MDEA or piperazine into AMP increased the absorption rate as compared to AMP alone. Of these additives, HMDA showed the most enhancement in the reaction rate of AMP. The reaction rate constants of HMDA, MDEA and piperazine blended into AMP at 303–343 K were given by kH = 3.84 × 1010exp(−5361/T), kM = 6.60 × 109exp(−4959/T), and kP = 9.09 × 109exp(−5058/T), respectively.

A novel and effective route to 1,3-oxazolidine derivatives. Palladium-catalyzed regioselective [3 + 2] cycloaddition of vinylic oxiranes with imines

Abstract Palladium-catalyzed intemolecular reaction of imines 1 with vinylic oxiranes 2 gives the regioselective [3 + 2] cycloaddition products, 1,3-oxazolidine derivatives 3 , in good to excellent yields. The present reaction permits the use of unconventional starting materials for the synthesis of 1,3-oxazolidines 3 .

Crystal structure and electronic properties of 2-amino-2-methyl-1-propanol (AMP) carbamate

A crystal structure of a carbamate of 2-amino-2-methyl-1-propanol (AMP-carbamate) has been elucidated and its structural and electronic properties investigated by density functional theory calculations and natural bond orbital analyses.

Tetrazole synthesis via the palladium-catalyzed three component coupling reaction.

The synthesis of tetrazoles was achieved via the palladium-catalyzed three component coupling (TCC) reaction; The TCC reaction of malononitrile derivatives, allyl acetate and trimethylsilyl azide proceeds very smoothly under a catalytic amount of Pd(PPh3)4 to give 2-allyltetrazoles, and further the TCC reaction of various activated cyano compounds, allyl methyl carbonate and trimethylsilyl azide proceeds readily under a catalytic amount of Pd2(dba)3 ≥ CHCl3 and (2-furyl)3P to give 2-allyltetrazoles. π-Allylpalladium azide complex is proposed as a key intermediate in the catalytic cycle and the [3 + 2] cycloaddition between the π-allylpalladium azide complex and cyano compounds most probably gives the tetrazole frameworks. The deallylation of the derived allyltetrazoles was attained via the two-step procedure; the ruthenium-catalyzed isomerization and ozonolysis.

Nucleophilicity and accessibility calculations of alkanolamines: applications to carbon dioxide absorption reactions.

Both nucleophilicities and accessibilities of three alkanolamines [monoethanolamine (MEA), (2-(methylamino)ethanol (MAE), and 2-amino-2-methyl-1-propanol (AMP)] were calculated to predict their reactivities with CO(2). After DFT geometry-optimization calculations, the global, group, and atomic nucleophilicities of each amine were obtained using MP2 quantum mechanical calculations. Only global nucleophilicity matched an experimental pK(a) order (MAE > AMP > MEA). However, it failed to predict the slow rate of the sterically hindered AMP and the order of rate constants, MAE > MEA > AMP. The accessibilities of amines to CO(2) have been calculated by MD simulations by monitoring collisions at the reaction centers: N atoms in amines and C in CO(2). The accessibility results indicate that global nucleophilicity needs quantitative correction for steric effects to predict better reactivities of amines with CO(2).

CATALYTIC PROPARGYLATION OF ALDEHYDES WITH ALLENYLTRIBUTYLSTANNANE BY YTTERBIUM TRIFLATE

Abstract The first ytterbium triflate [Yb(OTf) 3 ]-catalyzed propargylation of various aldehydes with allenyltributylstannane to afford homopropargyl alcohols in good yields is described. The present result provides a versatile tool for preparation of an array of homopropargyl alcohols from the reaction of aldehydes with allenyltributylstannane; which are known to possess low reactivity.

Catalytic and highly regiospecific carbon–carbon bond formation at α-position of Michael acceptor by palladium complex

Activated olefins react with allyl acetates and Bu3SnH in the presence of a catalytic amount of a palladium catalyst to afford the corresponding products which construct a new C-C bond selectively at the alpha-position of Michael acceptors.

Effect of pH on UV Photodegradation of N-Nitrosamines in Water

N-nitrosamines are a class of carcinogenic chemicals that can pose significant hazards to the human life. Ultraviolet (UV) light irradiation is considered as one of the effective methods to reduce N-nitrosamines in the aqueous phase. This study aimed to investigate the pH influence on UV photodegradation of N-nitrosamines (i.e., N-nitrosodibutylamine (NDBA) and N-nitrosopyrrolidine (NPYR)) closely related to water treatment. Photodegradation rate constants of NDBA and NPYR remained between 3.26×10 L/W-min to 5.08×10 L/W-min and 1.14×10 L/W-min to 2.80×10 L/W-min at pH2-10, respectively. This study also focused on the formation of oxidized products (i.e., primarily NO and NO). Under slightly acidic and neutral conditions, NO formation was more prevalent than NO formation, while under strong acidic conditions, NO was more prevalent. There was no significant change in total organic carbon (TOC) and total nitrogen (TN), suggesting negligible loss of N-nitrosamines and degradation products from the system. NDBA was easily photodegraded than NPYR. This study also demonstrated that a lower pH is a favorable condition for photolytic degradation of N-nitrosamines in water.