• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2708-2712
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• 2010

Amines, ammonia or 3-methoxypropylamine (MPA), are used to maintain the optimized pH for the prevention of corrosion in the secondary side of Pressurized Water Reactors (PWRs). They are differently dissociated as a function of temperature which is not same in each location of the water-steam cycle. pH at the operation temperature depends on temperature of fluid and equilibrium constants of water and amines. Thus, every amine provides the different pH in the entire secondary side so that pH is not only the sufficient parameter in corrosion control. The secondary parameter, i.e., buffer intensity, is the ability to maintain a stable pH when $H^+$ are added or removed due to the ingress of impurities or the reaction of corrosion. The buffer intensity is necessary to provide the selection criteria for the best pH control agent for secondary side and the basic understanding of the reason why the flow-accelerated corrosion(FAC) rate may demonstrate the bell-shape curve over temperature. The buffer intensities of ammonia and MPA were reviewed over the entire operation temperature of PWRs. The sufficient buffer intensity is provided for the inhibition of corrosion by ammonia in low temperature $(25{\sim}100^{\circ}C)$ and by DMA in high temperature $(150{\sim}250^{\circ}C)$. In terms of buffer intensity, i) the best pH control agent is an amine with $pK_a(T)$ range of pH(T)- $1{\leq}pK_a(T){\leq}pH(T)$ + 0.5 and ii) the amine solution should have sufficient buffer intensity, ${\beta}$ to inhibit corrosion, and iii) FAC rate may be maximum at the temperature, where ${\beta}_B/{\beta}$ ratio is lowest.

• Journal of Integrative Natural Science
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• v.10 no.4
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• pp.175-191
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• 2017

In organic chemistry amide synthesis is performed through condensation of a carboxylic acid and an amine with releasing one equivalent of water via the corresponding ammonium carboxylate salt. This method is suffering from tedious processes and poor atom-economy due to the adverse thermodynamics of the equilibrium and the high activation barrier for direct coupling of a carboxylic acid and an amine. Most of the chemical approaches to amides formations have been therefore being developed, they are mainly focused on secondary amides. Direct carbonylations of tertiary amines to amides have been an exotic field unresolved, in particular direct carbonylation of trimethylamine in lack of commercial need has been attracted much interests due to the versatile product of N,N-dimethylacetamide in chemical industries and the activation of robust N-C($sp^3$) bond in tertiary amine academically. This review is focused mainly on carbonylation of trimethylamine as one of the typical tertiary amines by transition metals of cobalt, rhodium, platinum, and palladium including the role of methyl iodide as a promoter, the intermediate formation of acyl iodide, the coordination ability of trimethylamine to transition metal catalysts, and any possibility of CO insertion into the bond of Me-N in trimethylamine. In addition reactions of acyl halides as an activated form of acetic acid with amines are reviewed in brief since acyl iodide is suggested as a critical intermediate in those carbonylations of trimethylamine.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2130-2134
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• 2014

A kinetic study is reported on nucleophilic substitution reactions of 4-nitrophenyl isonicotinate (7) with a series of cyclic secondary amines in MeCN. The plots of $k_{obsd}$ vs. [amine] curve upward for the reactions with weakly basic amines (e.g., morpholine, 1-(2-hydroxyethyl)piperazine, and piperazine) but are linear for those with strongly basic amines (e.g., piperidine and 3-methylpiperidine). The curved plots for the reactions with the weakly basic amines are typical for reactions reported previously to proceed through uncatalyzed and catalyzed routes with two intermediates (e.g., a zwitterionic tetrahedral intermediate $T^{\pm}$ and its deprotonated form $T^-$). In contrast, the linear plots for the reactions with the strongly basic amines indicate that the catalytic route (i.e., the deprotonation process to yield $T^-$ from $T^{\pm}$ by a second amine molecule) is absent. The Br${\o}$nsted-type plots for $Kk_2$ and $Kk_3$ (i.e., the rate constants for the uncatalyzed and catalyzed routes, respectively) exhibit excellent linear correlations with ${\beta}_{nuc}$ = 0.99 and 0.69, respectively. The effect of amine basicity on the reaction mechanism is discussed in detail.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2269-2273
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• 2012

Pseudo-first-order rate constants $k_{amine}$ have been measured spectrophotometrically for the reactions of benzyl 4-pyridyl carbonate 6 with a series of alicyclic secondary amines in $H_2O$ at $25.0^{\circ}C$. The plots of $k_{amine}$ vs. [amine] curve upward, indicating that the reactions proceed through a stepwise mechanism with two intermediates, a zwitterionic tetrahedral intermediate $T^{\pm}$ and its deprotonated form $T^-$. This contrasts to the report that the corresponding reactions of benzyl 2-pyridyl carbonate 5 proceed through a forced concerted pathway. The $k_{amine}$ values for the reactions of 6 have been dissected into the second-order rate constant $Kk_2$ and the thirdorder rate constant $Kk_3$. The Br${\o}$nsted-type plots are linear with ${\beta}_{nuc}=0.94$ and 1.18 for $Kk_2$ and $Kk_3$, respectively. The $Kk_2$ for the reaction of 6 is smaller than the second-order rate constant $k_N$ for the corresponding reaction of 5, although 4-pyridyloxide in 6 is less basic and a better nucleofuge than 2-pyridyloxide in 5.

• Bulletin of the Korean Chemical Society
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• v.18 no.5
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• pp.523-527
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• 1997

Apparent second-order rate constants (kapp) have been measured spectrophotometrically for the reaction of 2,4-dinitrophenyl benzoate (DNPB) with 6 secondary cyclic amines in H2O containing 20 mole% DMSO at 25.0±0.1 ℃. The Bronsted-type plot (log kapp vs. pKa) shows a break at pKa near 9.1, e.g. two straight lines with βapp values of 0.67 and 0.44 for the low basic (pKa < 9.1) and the highly basic (pKa > 9.1) amines, respectively. Using an estimated k2 value of 3×109 sec-1, all the other microconstants (k1, k-1 and K) involved in the present aminolysis have been calculated. The k value decreases with increasing the basicity of amines while k1 and K values increase with increasing the amine basicity, as expected. Good linear Bronsted-type plots have been obtained for these microconstants of the present aminolysis of DNPB. The magnitudes of the slope of the Bronsted-type plots, k1 and k-1 have been calculated to be 0.43 and - 0.24, respectively, indicating the k-1 step is about two folds less sensitive than the k1 step to the amine basicity. The K value has been calculated to be 0.66, which appears to be much smaller than the one for other aminolyses showing general base catalysis. The small K value has been attributed to the absence of general base catalysis in the present aminolysis of DNPB.

• Korean Journal of Pharmacognosy
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• v.1 no.3
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• pp.93-99
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• 1970

There have been reported by several workers for the isolation and determination of the amine derivatives as Metbylephedrine Hydrochloride and Ephedrine Hydrochloride adopting neutralization method, steam distillation method, non-aqous titration method, ion-exchange resin method, titration method after acetylation, colorimetric method, gravimetric method, iodine titration method and gas chromatography. Those methods mentioned in above, can be practically applied for the sample which is not mixed one mith the other amine compounds. Presently, it has not shown on the isolative determination of the mixed sample of amine derivatives. In this paper, it is discussed on the isolative determination of Methylephedrine Hydrochloride as the tertiary amine compound and Ephedrine Hydrochloride as the secondary amine compound. According to the results of the experiment, it could be summarized as follows: 1. There is no time-variation on the color reaction of Methylephedrine Hydrochloride and Ephedrine Hydrochloride with the color reagent, bromcresolgreen. And Methylephedrine Hydrochloride and Ephedrine Hydrochloride, respectively, can be determined spectrophotometrically by means oft his color reaction. 2. For the isolation of Methylephedrine Hydrochloride and Ephedrine Hydrochloride from the mixed sample, Methylephedrine Hydrochloride can be eluted by chloroform, while Ephedrine Hydrochloride by the mixed solvent of chloroform and ethylalcohol (2:1), from the celite column adsorbed at pH6.4 followed by extraction with ether undersodium hydroxide alkali re action. 3. When the sample is mixed with quinine hydrochloride, dihydrocodeine bitartate, and noscapine, these mixed compounds can be eliminated by means of stram distillation. 4. When the sample is mixed with chlorpheniramine maleate, dextromethorphan hydrobromide and diphenhydramine hydrochloride, the mixed compounds can be eliminated by means of steam distillation and celite adsorption column chromatography, In conclusion, the isolative determination method for Methylephedrine Hydrochloride and Ephedrine Hydrochloride studied in this paper, indicates with the excellent reproducibility and accuracy.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.5
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• pp.561-569
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• 2017

In this study, a synthetic amine made using the ethylene oxide-ammonia reaction was used as an absorbent to remove carbon dioxide. Existing absorbents were used in a mix in order to improve performance; however, because the ethylene oxide-ammonia reaction generates primary, secondary, and tertiary amines simultaneously, it has the merit that separate mixing of the absorbents was not needed. The performance of carbon dioxide absorption with the synthetic amine was compared to that of MEA. As a result of an experiment, it was determined that the $CO_2$ loading was 1.15 times better than that of MEA (a commonly used amine), while the cyclic capacity was 2.28 times higher. Because the heat of reaction was 1.10 times lower than for MEA, the synthetic amine showed superior performance in terms of absorption and regeneration.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.118-123
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• 1991

Potentially dangerous nitrosamines have been shown to result from the reaction of sodium nitrogusside with several drugs under physiological conditions (pH 7.3 and $37^\circ{C})$. In each case the products were identical to those produced upon reaction with nitrous acid at much lower pH values. Reaction rates were shown to reflect a first order dependence on both amine and nitroprusside concentrations and to increase at higher pH values, approximately in proportion to concentrations of unprotonated amine. Fast reactions of sodium nitroprusside with reduced glutathione, cysteine, and ascorbate suppress but do not prevent the conversion of amines into N-nitrosamines. These results show sodium nitroprusside to be very potent nitrosating agent under physiological conditions and suggested nitrosamines may be formed during its normal pharmacological administration.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.4
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• pp.241-247
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• 2000

This paper reports on an experimental study of the absorption of COS in a secondary amine diethanolamine. The primary objectives were to investigate an analogy between $N_2$O and COS, thereby allowing an estimation of the physical solubility and diffusivity of the sulfur gases in the reacting amine solutions. The solubilities and diffusivities of $N_2$O and COS in 5~25% aqueous polyethylene glycol at $25^{\circ}C$ were measured. The results appeared to verify the use of an $N_2$O-COS analogy for estimating the solubility and diffusivity of COS in aqueous solutions of alkanolamines up to an approximate 25 weight % concentration. The mean deviation of the $N_2$O analogy relative to the measured solubilities was 3.7%, and the mean deviation between the analogy and the measured diffusion coefficients using the experimental values for Hcos/PEG was 14.6%.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.23-27
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• 1997

The luminescence and excitation spectra of [Cr(trans-diammac)](ClO4)3 (trans-diammac=trans-6, 3-dimethyl-l, 4, 8, 11-tetraazacyclotetradecane-6, 13-diamine) taken at 77 K are reported. The mid and far-infrared spectra at room-temperature are also measured between 4000 cm-1and 50 cm-1. In the excitation spectrum the 2Eg components are splitted by 102 cm-1. Using the observed electronic transitions, a ligand field analysis was performed to determine more detailed bonding properties of the coordinated atoms toward chromium(Ⅲ). According to the results, we can confirm that the six nitrogen atoms have a strong σ-donor character, and the trans-diammac secondary amine has a greater value of eσ than does the primary amine.