- Synthesis of Terpineol from Alpha-Pinene Catalyzed by α-Hydroxy Acids
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We report the use of five alpha-hydroxy acids (citric, tartaric, mandelic, lactic and glycolic acids) as catalysts in the synthesis of terpineol from alpha-pinene. The study found that the hydration rate of pinene was slow when only catalyzed by alpha-hydroxyl acids. Ternary composite catalysts, composed of AHAs, phosphoric acid, and acetic acid, had a good catalytic performance. The reaction step was hydrolysis of the intermediate terpinyl acetate, which yielded terpineol. The optimal reaction conditions were as follows: alpha-pinene, acetic acid, water, citric acid, and phosphoric acid, at a mass ratio of 1:2.5:1:(0.1–0.05):0.05, a reaction temperature of 70? C, and a reaction time of 12–15 h. The conversion of alpha-pinene was 96%, the content of alpha-terpineol was 46.9%, and the selectivity of alpha-terpineol was 48.1%. In addition, the catalytic performance of monolayer graphene oxide and its composite catalyst with citric acid was studied, with acetic acid used as an additive.
- Hu, Yi-Ming,Huang, Xiao-Rui,Meng, Zhong-Lei,Qin, Rong-Xiu,Wen, Ru-Si,Zhou, Yong-Hong
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- Synthesis and kinetic regularities of the thermal decomposition of new hydrotrioxides of cyclic alcohols
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Cyclic hydrotrioxides were synthesized by low-temperature (?78 °C) ozonolysis of a series of cyclic alcohols and identified using 1H NMR spectra. The kinetic regularities of the thermal decomposition of the synthesized hydrotrioxides were studied. The experimental proof of the induced decomposition of alcohol hydrotrioxides was obtained for the first time using cyclohexanol hydrotrioxide as an example. The influence of cyclic substituents on the thermal stability of the hydrotrioxides is shown.
- Grabovskiy,Khalitova,Fedorova,Lobov,Rol’nik,Kabal’nova
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p. 464 - 468
(2017/03/08)
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- Synthesis and sweetness characteristics of L-aspartyl-D-alanine fenchyl esters
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Four isomers of the L-aspartyl-D-alanine fenchyl esters were prepared as potential peptide sweeteners. L-Aspartyl-D-alanine (+)-α-fenchyl ester and L-aspartyl-D-alanine (-)-β-fenchyl ester showed sweetness with potencies 250 and 160 times higher than that of sucrose, respectively. In contrast, L-aspartyl-D-alanine (+)-β-fenchyl ester and L-aspartyl-D-alanine (-)-α-fenchyl ester had the highest sweetness potencies at 5700 and 1100 times that of sucrose, respectively. In particular, L-aspartyl-D-alanine (-)-α-fenchyl ester had an excellent sweetness quality, but L-aspartyl-D-alanine (+)-β-fenchyl ester did not have an excellent quality of sweetness because it displayed an aftertaste caused by the strong sweetness.
- Yuasa,Nagakura,Tsuruta
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p. 5013 - 5018
(2007/10/03)
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- Chiral β- and γ-aminoalcohols derived from (+)-camphor and (-)-fenchone as catalysts for the enantioselective addition of diethylzinc to benzaldehyde
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The addition of Me3SiCN and LiCH2CN to (+)-camphor and (-)-fenchone, respectively, followed by reduction leads to chiral β- and γ-aminoalcohols. The enantioselectivities realized using these aminoalcohols as ligands in the addition of Et2Zn to benzaldehyde were lower than those obtained using the corresponding δ-aminoalcohols.
- Dimitrov, Vladimir,Dobrikov, Georgi,Genov, Miroslav
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p. 1323 - 1329
(2007/10/03)
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- High potency dipeptide sweeteners. 1. L-aspartyl-D-phenylglycine esters
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Twenty esters of L-aspartyl-D-phenylglycine, as well as two substituted analogues, an o-fluoro and a p-hydroxyphenylglycine ester, were prepared. The L-aspartyl-D-phenylglycine (-)-α- and (+)-β-fenchyl esters had the highest sweetness potency at 1200 and 3700 times that of sucrose, respectively. The high potency of these sweeteners is surprising as the phenyl group occupies a position previously believed to accommodate only much smaller groups.
- Janusz,Gardklik,Young,Burkes,Stoll,Estelle,Riley
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p. 1052 - 1061
(2007/10/02)
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- TERPENE AMINES. IV. SYNTHESIS AND STUDY OF THE STRUCTURE OF AMINES FROM d-FENCHONE
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The reductive amination of d-fenchone by aliphatic nitriles has been studied.A probable reaction pathway is suggested, and the stereochemical composition of the products has been determined.It has been established with the aid of 13C NMR that reaction forms a mixture of isomeric optically active N-alkyl-1,2,3-trimethylbicyclohept-2-ylamines with a 3:1 ratio of endo and exo isomers.The absolute configurations of the amines synthesized have been determined.
- Kozlov, N. G.,Kalechits, G. V.,Vyalimyae, T. K.
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p. 451 - 454
(2007/10/02)
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- Natural and Magnetic Circular Dichroism Soectra of Selenofenchone. Evidence for a Singlet-Triplet Component of the n -> ?* Transition of Selenoketones
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Blue (-)-selenofenchone (1) is observed to give a negative long-wavelength Cotton effect (CE) Δε573max = -0.86, in addition to a series of CE's down to 190 nm, Δε270max = -5.21, Δε232max = +4.90, in its circular dichroism (CD) spectrum measured in n-heptane.The long-wavelength CD (573 nm) and UV (625 nm) λmax of 1 are found surprisingly well separated.Support for the singlet-triplet nature of this electronic transition may be found in a sharp positive magnetic CD band centered near 630 nm in (+/-)-selenofenchone.The CD and UV data are compared with those of thiofenchone (2) and fenchone (3).
- Wijekoon, W. M. Donald,Bunnenberg, Edward,Records, Ruth,Lightner, David A.
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p. 3034 - 3037
(2007/10/02)
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- MECHANISM OF THE γ-RADIOLYSIS OF 2-PROPANOL SOLUTIONS OF CYCLOHEXANONES
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The γ-radiolysis of 2-propanol solutions of cyclohexanone gives mainly hydrogen, acetone, pinacol, methane derived from 2-propanol, and cyclohexanol, 2-(2-cyclohexanonyl)-cyclohexanone, and 3-(2-hydroxy-2-propyl)cyclohexanone derived from cyclohexanone.The radiolytic yields of all these products were highly dependent on the initial cyclohexanone concentration.The formation of cyclic alcohols by radioreduction has been extended to various substituted cyclohexanones.Radiolytically generated solvated electrons are scavenged by cyclohexanone, leading to the corresponding radical anions.The protonation of these radical anions gives rise to cyclohexanol via the dismutation of the hydroxycyclohexyl radicals.Steady state radiolysis measurements were complemented by pulse radiolysis in dilute solution.It was established that radical-anions and hydroxylated radicals decayed according to a second order rate law.When ketone concentration was lower than 0.1M, radiolytic yields were in agreement with the mechanism mentioned above.However, in concentrated media the large increase in G(cyclohexanol) cannot be only accounted for by the involvement of radiolytically generated solvated electrons; probably it is due to an electron transfer from the cyclohexanone enolate to cyclohexanone itself, thus generating extra amounts of cyclohexanone radical anions.
- Alipour, E.,Vidril, D.,Micheau, J. C.,Paillous, N.,Lattes, A.,et al.
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p. 2807 - 2814
(2007/10/02)
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