• Applied Chemistry for Engineering
• /
• v.27 no.1
• /
• pp.110-114
• /
• 2016

Cr(VI)-pyrazine complex (PZCC) was synthesized by the reaction of pyrazine with chromium (VI) trioxide in 6 M HCl. The structure was characterized using IR spectroscopy and inductively coupled plasma (ICP). The oxidation of benzyl alcohol using PZCC in various solvents showed that the reactivity increased with the increase of the dielectric constant, in the order: N,N'-dimethylform-amide > acetone > chloroform > cyclohexene. In the presence of N,N'-dimethylformamide solvent with an acidic catalyst such as sulfuric acid ($H_2SO_4$ solution), PZCC oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. Hammett reaction constant (${\rho}$) was -0.70 (308 K). The observed experimental data were used to rationalize the hydride ion transfer in the rate-determining step.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.10
• /
• pp.881-888
• /
• 1994

The approximate rates and stoichiometry of the reaction of excess sodium tris(diethylamino)aluminum hydride (ST-DEA) with selected organic compounds containing representative functional groups under standardized conditions(tetrahydrofuran, $0{\circ}$) were studied in order to characterize the reducing characteristics of the reagent for selective reductions. The reducing ability of STDEA was also compared with those of the parent sodium aluminum hydride (SAH) and lithium tris(diethylamino)aluminum hydride (LTDEA). The reagent appears to be milder than LTDEA. Nevertheless, the reducing action of STDEA is very similar to that observed previously for LTDEA, as is the case of the corresponding parent sodium and lithium aluminum hydrides. STDEA shows a unique reducing characteristics. Thus, benzyl alcohol, phenol and 1-hexanol evolved hydrogen slowly, whereas 3-hexanol and 3-ethyl-3-pentanol, secondary and tertiary alcohols, were essentially inert to STDEA. Primary amine, such as n-hexylamine, evolved only 1 equivalent of hydrogen slowly. On the other hand, thiols examined were absolutely stable. STDEA reduced aidehydes and ketones rapidly to the corresponding alcohols. The stereoselectivity in the reduction of cyclic ketones by STDEA was similar to that by LTDEA. Quinones, such as p-benzoquinone and anthraquinone, were reduced to the corresponding 1,4-dihydroxycyclohexadienes without evolution of hydrogen. Carboxylic acids and anhydrides were reduced very slowly, whereas acid chlorides were reduced to the corresponding alcohols readily. Esters and epoxides were also reduced readily. Primary carboxamides consumed hydrides for reduction slowly with concurrent hydrogen evolution, but tertiary amides were readily reduced to the corresponding tertiary amines. The rate of reduction of aromatic nitriles was much faster than that of aliphatic nitriles. Nitrogen compounds examined were also reduced slowly. Finally, disulfide, sulfoxide, sulfone, and cyclohexyl tosylate were readily reduced without evolution of hydrogen. In addition to that, the reagent appears to be an excellent partial reducing agent: like LTDEA, STDEA converted ester and primary carboxamides to the corresponding aldehydes in good yields. Furthermore, the reagent reduced aromatic nitriles to the corresponding aldehydes chemoselectively in the presence of aliphatic nitriles. Consequently, STDEA can replace LTDEA effectively, with a higher selectivity, in most organic reductions.

• Journal of the Korean Chemical Society
• /
• v.61 no.4
• /
• pp.151-156
• /
• 2017

A simple, green and chemo-selective method for the N-benzyloxycarbonylation of amines, ${\beta}$-amino alcohols, ${\alpha}$-amino esters and sulfonamides has been developed under microwave irradiation. Good to excellent yields of the N-benzyloxycarbamates compounds were obtained in short times without any side products.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.10
• /
• pp.3624-3628
• /
• 2011

Fr$\acute{e}$chet-type dendritic benzaldehydes were efficiently synthesized using 3,5-dihydroxybenzaldehyde as an aldehyde focal point functionalized unit by adding a generation to the existing dendron or direct oxidation of Fr$\acute{e}$chet-type dendritic benzyl alcohols. These dendritic benzaldehydes were applied for the construction of dendrimers containing secondary amines as connectors via Staudinger/aza-Wittig Reactions with ${\alpha}$,${\alpha}'$,-diazidop-xylene core.

• Journal of Environmental Science International
• /
• v.30 no.10
• /
• pp.879-889
• /
• 2021

This study characterizes the volatile aromatic and metabolite components of domestic native Apocynum lancifolium blossom. The accurate characterization of fragrances collected from the blossom was carried out using gas chromatography-mass. A total of 70 chemical components were identified, including ketones of acetophenone (29.22%), phenylethyl alcohol (10.54%), methyl-benzenemethanol (8.43%), benzyl alcohol (7.97%), natural bicyclic sesquiterpene types of caryophyllene (6.08%), gurjunene (6.20%), humulene (1.90%), and ocimene (1.04%). Overall, the content of ketones, alcohols, and terpenes was higher than that of others. The major metabolite components were pentanoic acid, malic acid, fructofuranoside, quinic acid, tagatose, sorbose, galactose, inositol, galactaric acid, glucopyranoside, and octadecenoic acid.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.11
• /
• pp.6000-6007
• /
• 2013

Cr(VI)-heterocyclic complex[Cr(VI)-isoquinoline] was synthesized by the reaction between of heterocyclic compound(isoquinoline) and chromium trioxide, and characterized by IR and ICP analysis. The oxidation of benzyl alcohol using Cr(VI)-isoquinoline in various solvents showed that the reactivity increased with the increase of the dielectric constant(${\varepsilon}$), in the order : cyclohexene$CH_3$, m-Br, m-$NO_2$). Electron- donating substituents accelerated the reaction, whereas electron acceptor groups retarded the reaction. The Hammett reaction constant(${\rho}$) was -0.69(308K). The observed experimental data have been ratiolized. The hydride ion transfer causes the prior formation of a chromate ester in the rate-determining step.

• Applied Chemistry for Engineering
• /
• v.28 no.5
• /
• pp.597-600
• /
• 2017

$(C_{10}H_8N_2H)_2Cr_2O_7$ was synthesized by reacting 4,4'-bipyridine and chromium (VI) trioxide. The structure of the product was characterized with FT-IR (infrared spectroscopy) and elemental analysis. The oxidation of benzyl alcohol using $(C_{10}H_8N_2H)_2Cr_2O_7$ in various solvents showed that the reactivity increased with the increase of the solvent dielectric constant, in the order of DMF (N,N'-dimethylformamide) > acetone > chloroform > cyclohexane. In the presence of DMF, an acidic catalyst such as $H_2SO_4$ $(C_{10}H_8N_2H)_2Cr_2O_7$ oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$). Electron donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. Hammett reaction constant (${\rho}$) was -0.70 (308 K). The observed experimental data were used to rationalize the hydride ion transfer in the rate determining step.

• Applied Chemistry for Engineering
• /
• v.34 no.3
• /
• pp.252-257
• /
• 2023

In this study, to replace phthalate-based plasticizers known as endocrine disruptors, compounds as plasticizer candidates were synthesized by using alcohols containing rings and fatty acids extracted from animal and vegetable oils, and their properties as plasticizers, including their plasticization efficiency, were evaluated. Nine compounds synthesized by esterification of fatty acids (caprylic acid, capric acid, lauric acid) and alcohols (solketal, benzyl alcohol, cyclohexanol) were identified by ¹H-NMR. The nine synthetic compounds were evaluated for their plasticity by adding them to PVC resin, and compared with the commercial plasticizers DEHP, DINCH, and ESO. According to the results, plasticization efficiency was 0.96 to 1.02 times higher than DEHP, 0.94 to 0.98 times higher than ESO, and 1.05 to 1.10 times higher than DINCH. Thermal stability was somewhat lower than that of DEHP and DINCH, but showed better results than ESO. The results of the solvent extraction test showed that both aqueous and oily solvents showed higher values than DEHP and DINCH but showed similar or superior properties to ESO.

• Korean Journal of Food Science and Technology
• /
• v.48 no.2
• /
• pp.122-127
• /
• 2016

The objective of this study was to identify the volatile compounds and aroma-active compounds from acai berry (Euterpe oleracea). Volatiles were isolated by high vacuum distillation using solvent-assisted flavor evaporation (SAFE) and liquid-liquid continuous extraction (LLCE). To identify the characteristic aroma-active compounds of acai berry, gas chromatography-mass spectrometry-olfactometry was used. Aroma-active compounds were evaluated by aroma extract dilution analysis (AEDA). A total of 51 and 54 volatile compounds from acai berry were identified from SAFE and LLCE extracts, respectively. Alcohols were confirmed to be important volatile compounds in acai berry, as the major volatile compounds were 2-phenylethanol, (Z)-3-hexenol, and benzyl alcohol. ${\beta}-Damascenone$ (berry, rose), trans-linalool oxide (woody), (Z)-3-hexenol (grass), and 2-phenylethanol (rose, honey) were considered the aroma-active compounds in acai berry. The most intense aroma-active compound of acai berry was ${\beta}-damascenone$.

• Journal of Life Science
• /
• v.16 no.7 s.80
• /
• pp.1243-1249
• /
• 2006

Volatile flavor compounds in commercial crab-like flavorants were compared by mean of solid phase microextraction(SPME) and liquid continuous extraction (LLCE)/GC/MSD methods. A total of 86 volatile flavor compounds were detected. Of these, 71 were positively identified consisting mainly of sulfur-containing compounds (13), aldehydes (3), ketones (2), esters (26), alcohols (5), aromatic compounds (3), terpenes (8), acids (2) and miscellaneous compounds (9). SPME method was more effective than LLCE method in detection of volatile components in commercial crab-like flavorants. Eight S-, N-containing compounds such as dimethyl sulfide, dimethyl disulfide, dipropyl disulfide, 3-(methylthio)propyl acetate, 3-(methylthio) propanal, 3-(methylthio) propanol, 2-methyl-3-(methylthio) pyrazine and 2-methyl-5-(methylthio) pyrazine, 8 esters such as styrallyl acetate, ethyl acetate, isoamyl acetate, benzyl acetate, ethyl pentanoate, butyl pentanoate, isoamyl pentanoate and furfuryl acetate were considered as major components in crab-like flavorants.