• Bulletin of the Korean Chemical Society
• /
• v.8 no.5
• /
• pp.408-414
• /
• 1987

The rate of bromine-exchange reaction between antimony tribromide and ${\alpha}-phenyl-n-butyl$ bromide in nitrobenzene has been determined, using antimony tribromide labelled with Br-82. The results indicate that the exchange reaction follows the first-order kinetics with respect to the organic bromide, and either the second- or first-order kinetics with respect to antimony tribromide depending on its concentration. The third-order rate constant obtained was 7.50 ${\times}10^{-2}l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. Similar study on the bromine-exchange reaction between antimony tribromide and ${\alpha}$-phenyl-i-butyl bromide has also been carried out. The results of the study show the same kinetic orders as the ones observed with $\alpha$-phenyl-n-butyl bromide. The third-order rate constant observed was 2.40 ${\times} 10^{-2} l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. The activation energy, the enthalpy of activation and the entropy of activation for the two exchange reactions mentioned above have been determined. The reaction mechanisms for the exchange reactions are discussed.

• Journal of the Korean Chemical Society
• /
• v.39 no.8
• /
• pp.643-649
• /
• 1995

The Menschutkin type reactions of substituted(Z)-benzyl systems with substituted(Y)-pyridines and N,N-dimethyl aniline have been studied by the electro-conductometric method in acetonitrile at 35$^{\circ}C$ and 50$^{\circ}C$. On the plot of $k_{obs}$ versus concentrations of nucleophile under pseudo-first order conditions, 3,$4-(CH_3/O)_2$-benzyl bromide and $4-CH_3O$-benzyl bromide were a positive intercept at zero concentration of nucleophile. The $k_1$ value for each compound was invariant with the different nucleoephile. However, $4-CH_3-$ and other electron withdrawing substituents of benzyl bromides did not show the positive intercept. These results are suggested that the reactions have been proceeding simultaneously and independently for the activated benzyl bromides via direct bimolecular and intimate ion pair intermediate.

• Analytical Science and Technology
• /
• v.12 no.2
• /
• pp.99-104
• /
• 1999

A stepwise gradient elution with two wavelengths detection was performed for the separation and determination of some anions in saline water. The eight anions such as iodate, bromate, nitrite, bromide, nitrate, chromate, iodide and thiocyanate were successfully separated using AS-7 column and sodium chloride/sodium phosphate buffer solution as an eluant within 40 min. The separation behaviors of anions were studied at various sodium chloride concentrations. The peak shapes of anions of bromate, nitrite, bromide and nitrate gradually broadened as the concentration of sodium chloride increased until 1.0 M in the sample solutions. However, no effect was observed in the peak shapes of chromate, iodide and thiocynate. A good linearity was obtained at the range of ppm(mg/L). The detection limit was proved to be $10-720{\mu}g/L$ for the eight anions with $50{\mu}L$ injection volume. This method was applied to the determination of $Br^-$, ${NO_3}^-$ and $I^-$ in sea water.

• Analytical Science and Technology
• /
• v.9 no.2
• /
• pp.139-144
• /
• 1996

The spectrophotometric determination method of scandium with eriochrome cyanine R(ECR) and the composition ratio of the complex were investigated in the presence of surfactants. The absorbance increase and red shift of maximum adsorption wavelength of Sc(III)-ECR complex were observed in cetyltrimethylammonium bromide (CTMAB), but those changes were not observed in the sodium dodecyl sulfate(SDS) and Triton X-100. A volume of 5ml of $1{\times}10^{-3}M$ ECR and 10ml of $2{\times}10^{-4}M$ CTMAB are necessary for the determination of $1{\times}10^{-7}{\sim}3.0{\times}10^{-6}M$ Sc(III) at pH 6.5. The apparent molar absorption coefficient of the Sc(III)-ECR-CTMAB, temary complex at 610nm is $5.6{\times}10^5mol^{-1}cm^{-1}L$ and its detection limit is $1.0{\times}10^{-7}M$. The binary complex composition of Sc(III)-ECR is 1:2 and the ternary complex composition of Sc(III)-ECR-CTMAB is 1:3:1.

• Food Science and Preservation
• /
• v.5 no.3
• /
• pp.199-206
• /
• 1998

Comparative effects of gamma irradiation and methyl bromide (MBr) fumigation on disinfestation and some physicochemical attributes of acorn seeds were investigated. Insects in domestic acorns were identified to be Curculio dentipes Roelofs and Dichocrocis punctiferalis Guenee, which were easily disinfestated immediately after commercial MBr fumigation. Irradiation also showed similar effects on mortality of the insects in different post-irradiation periods; at 3rd day with doses of 1-3 kGy and at around 30th day 0.5-1 kGy. MBr fumigation caused the decrease in lightness (Hunter L value), total phenolics and reducing sugars and the increase in yellowness (Hunter b value) and browning intensity for the subjected samples, as compared with the nontreated control and irradiated ones at 0.5-2 kGy. Furthermore, MBr fumigation resulted in decay for the most part of samples during storage at 5-10 $^{\circ}C$ for 6 months in a PVC box packaging with nets. As a result, optimum levels of irradiation is expected to be roe of the alternatives to chemical fumigants.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.30 no.3
• /
• pp.444-449
• /
• 2001

Comparative effects of gamma irradiation and methyl bromide (MeBr) fumigation on disinfestation and physicochemical attributes of mung bean were investigated. Insects in domestic mung bean were identified to be Collosobruchus chinensis Linne. Ina disinfestation test, MeBr showed 100% disinfestation effect on Larva and adult at 5th day after treatments, while irradiation dose above 3 kGy was effective for disinfesting all larva at that time. Adults were more sensitive to radiation than larva. Around 1 kGy was enough to control larva and adult in mung bean following 10 to 15 days of irradiation. In physicochemical properties of treated sampels, nitrogen solubility, TBA value, amino acid and fatty acid compositions were not different among the control, 2.5 kGy-irradiated and MeBr-fumigated samples. MeBr fumigation caused the decrease in lightness (Hunter's L value) and the increase in redness (a value) and yellowness (b value), thereby resulting in overall color difference (${\Delta}E$) in a noticeable level (NBS 2.61~2.94).

• Korean journal of applied entomology
• /
• v.21 no.3 s.52
• /
• pp.133-137
• /
• 1982

An experiment was conducted to find out the proper and effective fumigation method for harvested fresh chestnuts produced in Korea. Fumigation with phosphine, causing damages on chestnuts by rapid corruption or change in color on pericarp, did not completely kill chestnut curculio and nut fruit tortrix larvae in harvested fresh chestnuts regardless of long exposure of chestnuts to phosphine. Any damages not being appeared by fumigant, fumigation with methyl bromide at $40g/m^3$ for 4 hours at $21^{\circ}C$ would retain the low control against inclusion of any chestnut pests tested. Though fumigation with methyl bromide at $50g/m^3$ for 24hours was effective against any larvae of chestnut insects control, they caused serious damages by making the flesh surface of harvested fresh chests dark or dense brown. However, fumigation with methyl bromide at $50g/m^3$ for 4 hours at $21^{\circ}C$ resulted in complete kill of larvae of Curculio dentipes and Carpocapsa splendana in harvested fresh chestnuts with no significant damages on the treated fruits.

• Polymer(Korea)
• /
• v.33 no.4
• /
• pp.326-332
• /
• 2009

New humidity-sensitive monomer, N-methacryloyl-N'-ethyl-N'-propyl piperazinium bromide (MANEPPB) was prepared by the quaternization reaction of N-methacryloyl-N'-ethyl piperazine (MANEP) with 1-bromopropane. Polyelectrolytes derived from the copolymers composed of MANEPPB/MMN/AA=60/35/5, 70/25/5, 80/15/5, 90/5/5 and 95/0/5 were prepared for the humidity-sensitive membranes, which were fabricated on the gold electrode by dipping method and were crosslinked by reacting copolymers with aziridine crosslinker, trimethylolpropane tris(2-methyl-1-aziridinopropionate) (TTAP). When the resistance dependences on the relative humidity of the sensors were measured, it was found that the resistance varied three orders of magnitude between 20 and 90%RH, which was satisfied with the requirement for the common humidity sensor operating at ambient humidity. Their hysteresis, temperature dependence, frequency dependence, response and recovery time and water durability were measured and evaluated as a humidity-sensing membrane.

• Food Science and Preservation
• /
• v.10 no.3
• /
• pp.381-387
• /
• 2003

‘Fuji’ apples were treated by gamma irradiation (0 - 3 kGy) or methyl bromide fumigation at commercial conditions (MeBr, 26 g/kg, 4 hr) for quarantine purposes at two different treatment timing after harvest and stored under air at 0$^{\circ}C$ for 4 months. Associated with the treatment timing of irradiation or fumigation, after 40 days of storage at 0$^{\circ}C$ following harvest was more adequate than immediately after harvest in keeping qualities of stored apples. However, more than 2 kGy irradiation and MeBr fumigation were detrimental to physiological and chemical qualities of the fruits. These results show that less than 1 kGy irradiation at the delayed timing has a possibility to be applied as a quarantine procedure without significant changes in the quality of apples.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.2
• /
• pp.173-182
• /
• 2018

As part of planning for waste minimization, decontamination foam has been considered as a potential application for the cleaning of radioactive contaminant. In this study, we synthesized silica particles to improve foam stability by varying synthesis parameters. Cetyltrimethylammonium bromide (CTAB) was found to influence the stability of the decontamination foam. The reason was that higher interaction between $SiO_2$ nanoparticles and surfactant at the air-water interface in aqueous solution is beneficial for foam stability. CTAB can also be used as an additive for the aggregation of silica nanoparticles. In the separation of $SiO_2$ nanoparticles, CTAB plays a critical role in the nanoparticles flocculation because of the charge neutralization and hydrophobic effects of its hydrocarbon tails.