- 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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- Oxidation of secondary alcohols using solid-supported hypervalent iodine catalysts
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It is shown how secondary alcohols are oxidized to provide the corresponding ketones by use of Oxone and solid-supported hypervalent iodine catalysts. Under experimentally simple conditions with acetonitrile at elevated temperatures, excellent conversions were achieved with low catalyst loadings (0.2-5 mol%) when employing the conjugates 5 and 6 derived from IBX and IBS. The catalysts are broadly applicable to a range of alcohol substrates. Of primary importance with respect to sustainability issues, the metal-free catalysts are easily removed from the reaction mixture through filtration, and they can be re-used in oxidation processes for multiple times, without loss of catalytic activity.
- Ballaschk, Frederic,Kirsch, Stefan F.
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supporting information
p. 5896 - 5903
(2019/11/11)
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- Secondary Phosphine Oxides as Multitalented Preligands En Route to the Chemoselective Palladium-Catalyzed Oxidation of Alcohols
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Secondary phosphine oxides O=PHR2 (SPOs) were identified as multitalented preligands for the chemoselective Pd-catalyzed oxidation of alcohols by a hydrogen-abstracting methodology. SPOs were found to promote the hydrogen-abstraction step as well as hydrogen transfer to a Michael acceptor by generating a putative active H?Pd species. The catalytic system operates under neutral conditions and was proven to be compatible with various electrophilic and nucleophilic functionalities within the substrates as well as water- and air-sensitive functional groups.
- Vasseur, Alexandre,Membrat, Romain,Gatineau, David,Tenaglia, Alphonse,Nuel, Didier,Giordano, Laurent
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p. 728 - 732
(2017/03/13)
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- The Chemistry of Terpenes. Part 26. A Re-examination of the Neutral Products of the Oxidation of (-)-Fenchone, and (+)-2-endo-Fenchyl Acetate, and of the Bromination of (+)-Fenchone.
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A re-examination of the products of oxidation of (-)-fenchone (1) with chromyl acetate in acetic acid has confirmed that (-)-fenchane-2,5-dione (2) and (+)-fenchane-2,6-dione (3) are the main products.Two other compounds have been isolated, namely (+)-(1R)-6-exo-acetoxy-3,3,6-trimethyltrinorbornan-2-one (4) and (+)-(1R,2S,6R)-2,8,8-trimethyl-3,5-dioxatricyclo2,6>decane-4,9-dione (5).Similar oxidation of (+)-2-endo-fenchyl acetate (6) yields (-)-(1S)-2-endo-acetoxy-1,3,3-trimethyltrinorbornan-5-one (7), (+)-(1R)-2-endo-acetoxy-1,3,3-trimethyltrinorbornan-6-one (8), (+)-(1S)-2-endo-5-exo-diacetoxy-1,3,3-trimethyltrinorbornane (9), (+)-(1R,5S)-7-endo-acetoxy-1,6,6-trimethyl-3-oxabicyclooctane-2,4-dione (10), and (-)-(1S,3S,7S,8R)-8,10,10-trimethyl-4,6-dioxatricyclo3,8>decane-2,5-dione (11).Derivatives of these compounds are described.Bromination of (+)-fenchone (12) in presence of copper gave (+)-(1R)-1-bromomethyl-3,3-dimethyltrinorbornan-2-one (13) as the major product, but a significant amount of (-)-(1R)-7-anti-bromo-1,3,3-trimethyltrinorbornan-2-one (14) was also formed.Minor amounts of (+)-(1R)-3-endo-bromo-1,7,7-trimethyltrinorbornan-2-one (15), and probably (g.l.c.) either 5-exo- or 6-exo-bromofenchone, were formed.Methanolysis of the anhydride (10) affords the half-ester (16) from which the β-lactone (17) is obtained.
- Cocker, Wesley,Gordon, Robert L.,Shannon, Patrick V. R.
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p. 2101 - 2147
(2007/10/02)
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