• 펄프종이기술
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• 제29권3호
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• pp.51-59
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• 1997

Dissolving pulp is a low yield(30∼35%) bleached chemical pulp that has a high cellulose content (95% or higher) suitable for use in cellulose derivatives such as rayon, cellulose acetate. This research was studied for dissolving pulp preparation as the raw material of viscose rayon from commertial pulps. (TMP, CP, DIP) In the change of pulp(cellulose) characteristics after sodium hypochlorite and solvolysis treatment. the following results were obtained In the case of sodium hypochlorite pretreatment, we have obtained pulp that high purity cellulose, but degree of polymerization was inclined to decrease less than 170∼240. Comparing sodium hypochlorite pretreatment and solvolysis pretreatment, solvolysis pretreatment is superior to sodium hypochlorite process for making dissolving pulp. We think that the low degree of polymerization of cellulose because of increasing degradation of cellulose during delignification treatment.

• Bulletin of the Korean Chemical Society
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• 제11권2호
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• pp.99-105
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• 1990

The Gutmann acceptor number(AN), solvatochromic parameters $({\alpha},{\beta}\;and\;{\pi}^{\ast})$ and hydrogen bonding equilibrium constants (KHB) were determined for three binary systems of methanol with 1,2-dimethoxyethane(DME), 1,2-dichloroethane(DCE) and pyridine (PYD). The solvolysis rate constants of t-butyl chloride, bromide and iodide were also determined in the three binary systems. Solvent properties and solvolysis rates have been discussed in the light of various solvent parameters. Solvolysis of t-butyl halides are most conveniently explained by the two-stage mechanism involving ion-pair intermediate with the ion-pair formation for chloride and ion pair dissociation for iodide as rate limiting.

• Bulletin of the Korean Chemical Society
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• 제8권5호
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• pp.393-398
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• 1987

Solvolyses of 2-phenylethyl benzenesulfonates have been studied in methanol-water mixtures. Cross interaction constants, $\rho_{YZ}$, between substituents Y in the substrate and Z in the leaving group indicated somewhat closer distance between the two substituents than expected for the reaction system, which supported the involvment of phenyl group assisted pathway in the solvolysis. A smaller magnitude of $\rho_{YZ}$for MeOH was interpreted as the enhencement of solvent assisted pathway since MeOH is more nucleophilic than $H_2O$. Other selectivity parameters, Winstein coefficient m, Hammett's $\rho_Y^{+_Y}$ and $\rho_Z$, as well as activation parameters supported the participation of aryl assisted and aryl unassisted pathways in the $S_{N^2}$ process of the solvolysis reaction.

• Bulletin of the Korean Chemical Society
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• 제13권4호
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• pp.395-398
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• 1992

Rate of solvolysis of dansyl chloride in aqueous binary mixtures of acetone, methanol and ethanol are reported. Kinetic solvent isotope effects in methanol and product selectivities in alcohol-water mixtures are also reported. Kinetic data are interpreted with the Grunwald-Winstein and Kivinen equations. The value of $k_{CH3OH}/k_{CH3OD}=1.76$ suggests that a general have catalyzed and/or an $S_AN$ pathway is operative in methanol, a less polar solvent. Rate-rate profiles for solvolysis of dansyl chloride in the aqueous binary media indicate a change in reaction channel from $S_AN$ (in less polar media) to $S_N2$ (in more polar media) mechanism.

• Bulletin of the Korean Chemical Society
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• 제16권4호
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• pp.363-369
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• 1995

Hydroiminoacylations of allyl and homoallyl alcohol and their derivatives with benzaldimine by Wilkinson's complex have been studied. All these terminal alkene derivatives except allyl alcohol were hydroacylated according to anti-Markownikoff's rule to give the corresponding linear alkyl compounds without showing oxygen directing effect, even though hydroiminoacylation of 3-acetoxy-1,5-hexadiene showed strong allyloxy directing effect over homoallyloxy directing effect in a 92:8 ratio. Solvolysis of 4-acetoxy-1-phenylbutan-1-one, previously prepared by hydroiminoacylation, in ethanol led to etherification giving 4-ethoxy-1-phenylbutan-1-one through neighbouring group participation, while that of 5-acetoxy-1-phenylpentan-1-one led to common transesterification giving 5-hydroxy-1-phenylpentan-1-one. Application of branched alkanols such as isopropanol and t-butanolin solvolysis of 4-acetoxy-1-phenylbutan-1-one underwent competition between etherification and transesterification.

• 대한환경공학회지
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• 제36권4호
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• pp.231-236
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• 2014

톱밥은 목재부산물로 생산되는 바이오매스 자원으로 액화할 경우 가솔린에 함유된 고옥탄가 물질과 유사한 화학구조를 가지고 있기 때문에 액체 연료물질로서 사용할 수 있는 가능성이 높다. 본 연구에서는 톱밥의 열화학적 전환방법으로 아세톤-용매분해반응을 실시하여 반응온도, 반응시간, 용매의 종류가 미치는 영향과 분해 생성물 등과 같은 분해특성을 조사하였다. 아세톤-용매분해반응에 의해 톱밥으로부터 생성된 액상 생성물은 다양한 케톤, 페놀 및 퓨란 화합물이었다. 액상생성물의 연소열량은 7,824 cal/g이었으며, $350^{\circ}C$, 40분에서 액상생성물의 에너지 수율과 질량수율은 각각 60.8%, 386.4 g-oil/100 g-sawdust를 얻었다. 아세톤을 사용한 톱밥의 용매 열분해 반응시 생성된 주요물질은 4-methyl-3-pentene-2-one, 1,3,5-trimethylbezene, 2,6-dimethyl-2,5-heptadiene-4-one, 3-methyl-2-cyclopenten-1-one 등과 같은 케톤화합물로서 고옥탄가의 액체 연료로 사용 가능한 물질인 것으로 판단되었다.

• Bulletin of the Korean Chemical Society
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• 제6권1호
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• pp.19-23
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• 1985

Solvolysis of 1-adamantyl chloride, -bromide and -tosylate have been studied in methanol-acetonitrile mixtures. Rate maxima were found for 1-adamantyl bromide and tosylate at 80-90 % methanol mixtures. The rate maximum observed was interpreted as a result of cooperative enhancement of cation and anion solvation. 1-Adamantyl tosylate had small cation solvation but had extensive anion solvation. It was concluded that the Y scale based on adamantyl tosylate is superior to others since it varies in a wide range especially for weakly ionizing medium.

• Bulletin of the Korean Chemical Society
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• 제10권1호
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• pp.47-50
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• 1989

The methanolysis reactions of phenylacetyl chlorides have been investigated in methanol-acetonitrile mixtures at temperatures ranging - $15.0-0.0^{\circ}C.$ Substituent and solvent effects on the rate supported an associative $S_N2$ mechanism for the solvolysis. Activation parameters indicated that the reaction is entropy controlled, while the a/s ratios of the Taft's solvactochromic correlation proved to be remarkably constant with a typical value of 0.50 that is consistent for the reactions proceeding by a typical $S_N2$ path.

• Bulletin of the Korean Chemical Society
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• 제3권3호
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• pp.92-98
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• 1982

Solvolysis reactions of some substituted benzoyl chlorides were studied in ethanol-water, ethanol-trifluoroethanol and methanol-acetonitrile mixtures. Results showed that the reaction proceeds via an $S_N2$ process in which bond formation is more advanced than bond cleavage. Comparison of the two models for predicting transition state variation indicated superior nature of the quantum mechanical model relative to the potential energy surface model.

• 대한화학회지
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• 제31권1호
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• pp.37-44
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• 1987

몇가지 이성분 혼합용매(물-메틸알코올, 물-아세톤, 물-이소프로필알코올, 물-에틸렌글리코올)에서 $cis-[Co(en)_2Cl_2]^+$착이온의 가용매분해반응속도를 분광광도법을 이용하여 압력(1~1500bar)에 따라 측정하였다. 속도상수에 대한 압력의 영향으로부터 구한 활성화체적은 메틸알코올, 아세톤, 이소프로필알코올, 에틸렌글리코올에서 각각 1.13∼4.44, 1.13~3.59, 0.82~3.44, 1.13~2.68cm3mole-1이었다. 또한 메틸알코올에서는 촉매제로 Fe(Ⅱ)이온을 사용하여 가용매분해반응속도를 측정하였고, 활성화체적은 -0.56∼1.59cm3mole$^{-1}$이었다. 가용매분해반응성은 자유에너지변화사이클과 활성화체적을 이용하여 고찰하였다.