106-21-8Relevant articles and documents
The effect of catalyst preparation conditions on the synthesis of menthol from citronellal on Ru/H-BEA
Pl??er, Jutta,Dedeaga, Fatma,Lucas, Martin,Claus, Peter
, p. 100 - 108 (2016)
Heterogeneous Ru/H-BEA catalysts are suitable catalysts for the one-pot transformation of citronellal to menthols, which requires a combined cyclization-hydrogenation step. Here, we report the role of different preparation conditions-namely the choice of the Ru-precursor (Ru(NO)(NO3)3), Ru(acac)3, RuCl3 and Ru3(CO)12) as well as the reduction temperature (523-923 K) of the catalyst. Using Ru(NO)(NO3)3 as precursor the highest activity was obtained, while the product distribution was not strongly affected by the choice of the precursor. On the contrary the reduction temperature leads to very different product distributions: Increasing it from 623 K to 923 K for a 1%Ru/H-BEA-25 catalyst the competitive hydrogenation of citronellal was diminished, which leads to an increased selectivity to menthols from 77% to 87% and additional the activity increases with a factor of 3.4. This behaviour might be due to a dealumination of the zeolite during reduction at higher temperatures. Moreover, in combination with appropriate reaction conditions a yield to menthols of 92% can be reached.
SYNTHESIS OF ETHYL 3,7,11-TRIMETHYL-2,4-DODECADIENOATE (HYDROPRENE) FROM 4-METHYLTETRAHYDROPYRAN
Odinokov, V. N.,Ishmuratov, G. Yu.,Kharisov, R. Ya.,Lomakina, S. I.,Tolstikov, G. A.
, p. 1768 - 1770 (1989)
A new pathway has been proposed for the synthesis of the ethyl ester of 3,7,11-trimethyl-2,4-dodecadienoate (juvenoid hydroprene) from available 4-methyltetrahydropyran.The cleavage of the latter to 3-methyl-5-bromo-1-acetoxypentane and coupling with isobutylmagnesium bromide gave tetrahydrogeraniol, which was oxidized to the corresponding aldehyde.The reaction of this aldehyde with allylmagnesium chloride and subsequent oxidation by O2/PdCl2-CuCl led to 6,10-dimethyl-3E-undecen-2-one, which was converted by a known method to the desired product as a mixture of 70 percent 2E,4E- and 30 percent 2Z,4E-stereoisomers.The yield of hydroprene in the six-step synthesis was 32 percent relative to 4-methyltetrahydropyran.
Parham,Holmquist
, p. 1173 (1954)
Blau et al.
, p. 206,207 (1970)
Colloidal noble-metal and bimetallic alloy nanocrystals: A general synthetic method and their catalytic hydrogenation properties
Song, Shuyan,Liu, Ruixia,Zhang, Yu,Feng, Jing,Liu, Dapeng,Xing, Yan,Zhao, Fengyu,Zhang, Hongjie
, p. 6251 - 6256 (2010)
A general single-step strategy has been developed for the direct thermal decomposition of noble-metal salts in octadecylamine to synthesize octahedron- and rod-shaped noblemetal aggregates and monodisperse noble-metal or bimetallic alloy nanocrystals without introducing any additive into the system. It has presented a facile and economic way to fabricate these nanocrystals, especially alloy nanocrystals, which does not require a post-synthesis solid-state annealing process. The morphology of the nanocrystals can be easily controlled by tuning the synthetic temperature. Their ability to catalyze heterogeneous Suzuki coupling reactions has been investigated and showed satisfactory catalytic activity. The catalytic performanee of the monometallic and bimetallic alloy nanocrystals were also evaluated in the selective hydrogenation of citral in a conventional organic solvent (toluene) and a green solvent (supercritical carbon dioxide, scCO2). Interestingly, the catalysts performed differently to each other when they were in ScCO2 owing to the different morphology, which should be readily optimized for further use.
Selective hydrogenation of citral over a carbon-titania composite supported palladium catalyst
Zhu, Jie,Lu, Mohong,Li, Mingshi,Zhu, Jianjun,Shan, Yuhua
, p. 655 - 660 (2011)
A novel carbon-titania composite material, C/TiO2, has been prepared by growing carbon nanofibers (CNFs) on TiO2 surface via methane decomposition using Ni-Cu as a catalyst. The C/TiO2 was used for preparing supported palladium catalyst, Pd/C/TiO2. The support and Pd/C/TiO2 catalyst were characterized by BET, SEM, XRD and TG-DTG. Its catalytic performance was evaluated in selective hydrogenation of citral to citronellal, and compared with that of activated carbon supported Pd catalyst. It was found that the Pd/C/TiO2 catalyst contains 97% of mesopores. And it exhibited 88% of selectivity to citronellal at citral conversion of 90% in citral hydrogenation, which was much higher than that of activated carbon supported Pd catalyst. This result may be attributed to elimination of internal diffusion limitations, which were significant in activated carbon supported Pd catalyst, due to its microporous structure. A novel palladium catalyst supported on carbon-titanium composite, Pd/C/TiO 2, has been prepared via chemical reduction process. It contains 97% mesopores and exhibited higher selectivity to citronellal in citral hydrogenation compared to formed activated carbon supported palladium catalyst, which was attributed to elimination of internal diffusion limitations.
New terpene hydrocarbons from the alligatoridae (crocodylia, reptilia)
Schulz, Stefan,Krueckert, Karsten,Weldon, Paul J.
, p. 34 - 38 (2003)
The contents of the paracloacal gland secretions of the alligatorids Alligator mississippiensis, A. sinensis, Paleosuchus palpebrosus, and P. trigonatus were investigated. Novel acyclic hydrocarbon terpenes with a rare trisubstituted 2,4-diene system were identified in the secretions of A. sinensis, P. palpebrosus, and P. trigonatus. The structures of the monoterpene (2E,4E)-3,7-dimethyl-2,4-octadiene (9) and the sesquiterpene (2E,4E,7S)-3,7,11-trimethyl-2,4-dodecadiene (14) were proven by synthesis and gas chromatography on a chiral phase. Several other new terpenes (11, 16, 17, 18, 19, and 20) related to these components also were present in the secretions, as well as the known compounds myrcene (6), (E)-β-farnesene (4), (E)-β-springene (3), squalene (5), cembrene A (1), and 11,12-dihydrocembren-10-one (2).
Selective catalytic activity of ball-shaped Pd@MCM-48 nanocatalysts
Lee, Hee-Yoon,Ryu, Suyoung,Kang, Hongkyu,Jun, Young-Wook,Cheon, Jinwoo
, p. 1325 - 1327 (2006)
Remarkable selectivity is achieved in the cleavage of benzyl ethers using ball-shaped palladium nanocatalysts, Pd@MCM-48, in an MCM-48 matrix. The unique nanocatalysts not only feature unprecedented complete hydrogenolysis selectivity of a benzyl ether over hydrogenation of a double bond, but also demonstrate selective cleavage of unsubstituted benzyl ether over substituted benzyl ethers. The Royal Society of Chemistry 2006.
Liquid-phase hydrogenation of citral over Pt/SiO2 catalysts - II. Hydrogenation of reaction intermediate compounds
Vannice,Singh,Sysak
, p. 181 - 191 (2000)
Liquid-phase hydrogenation of the four principal reaction intermediates during citral hydrogenation (nerol, geraniol, citronellal, and citronellol) was studied at 298 and 373 K under 20 atm H2 at concentrations of 0.5-1M in hexane. Decomposition of geraniol and nerol to form adsorbed CO on Pt as an inhibitor was proposed to be responsible for the activity minimum observed during citral hydrogenation. A decrease in the initial reaction rate as temperature increased from 298 to 373 K was exhibited during the hydrogenation of all four compounds. Furthermore, simultaneous hydrogenation of citronellal and geraniol at 298 K resulted in a continuous decrease in the rate of citronellal disappearance in contrast to the nearly constant rate of disappearance observed during hydrogenation of citronellal alone. Competitive hydrogenation of citral with either geraniol or citronellal showed that geraniol hydrogenation to citronellol was kinetically insignificant during citral hydrogenation at 373 K. The relative rates of hydrogenation of the compounds indicated that the hydrogenation rate of the C=C bond in this family of compounds was greater than that of the C=O bond, as evidenced by the ordering of the hydrogenation activity: geraniol > nerol > citronellol > E-citral > citronellal _ Z-citral. The product distributions obtained during hydrogenation of citronellal indicated that higher reaction temperatures favor activation of the C=O bond relative to the C=C bond.
A novel type of Pd/C-catalyzed hydrogenation using a catalyst poison: Chemoselective inhibition of the hydrogenolysis for O-benzyl protective group by the addition of a nitrogen-containing base
Sajiki, Hironao,Hirota, Kosaku
, p. 13981 - 13996 (1998)
A mild and chemoselective hydrogenation method for a variety of reducible functional groups distinguishing front aliphatic and aromatic' benzyl ethers was accomplished by the addition of an appropriate nitrogen- containing base to the Pd/C-catalyzed hydrogenation system.
Regioselective hydrogenation of unsaturated alcohol using platinum-alumina modified with carboxylic acid
Kuno,Takahashi,Shibagaki,Matsushita
, p. 3779 - 3782 (1989)
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Universal approach to the synthesis of juvenoid hydroprene and methoprene from 4-methyltetrahydropyran
Ishmuratov,Yakovleva,Galyautdinova,Faifer,Kharisov,Zorin,Tolstikov
, p. 486 - 489 (2001)
A universal approach to the synthesis of juvenoid hydroprene and methoprene was developed on the basis of monoalkylation of acetoacetate by 1-acetoxy-5-bromo-3-methylpentane, the product of acidic decyclization of 4-methyltetrahydropyran.
Simple H2-free hydrogenation of unsaturated monoterpenoids catalyzed by Raney nickel
Philippov, Alexey A.,Chibiryaev, Andrey M.,Martyanov, Oleg N.
, p. 380 - 381 (2019)
A series of monoterpenoids (citral, carvone, menthone, camphor) as well as cyclohexanone and hex-5-en-2-one were subjected to transfer hydrogenation with PriOH/Raney nickel system at 82 or 150 °C. Among monoterpenoids, citral and carvone underwent full conversion at 82 °C within 5 h.
A tandem cyclization and hydrogenation of (±)-citronellal to menthol over bifunctional Ni/Zr-beta and mixed Zr-beta and Ni/MCM-41
Nie, Yuntong,Niah, Weilin,Jaenicke, Stephan,Chuah, Gaik-Khuan
, p. 1 - 10 (2007)
The addition of nickel to Zr-beta gave a useful bifunctional catalyst that combines a high rate of cyclization of (±)-citronellal to isopulegols over zirconium sites and subsequent hydrogenation to menthols. The diastereoselectivity to the desired (±)-menthol was 90%. A loading of 4 wt% is optimal; lower loadings led to a low rate of hydrogenation, whereas a higher nickel loading appears to block the zirconium Lewis acid sites essential for the cyclization of citronellal. A mixture of Zr-beta and Ni/MCM-41 also formed an effective bifunctional catalyst system where the selectivity toward menthols remained high even with nickel loadings up to 15 wt%. The yield of (±)-menthol over the dual-catalyst system was 86-89% with 93 %, although the diastereoselectivity to (±)-menthol was lower (85%). In comparison, a 2% Pd/Zr-beta catalyst exhibited lower activity and selectivity to menthols, forming substantial amounts of 3,7-dimethyloctanal.
Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalyst
Er?nen, Kari,M?ki-Arvela, P?ivi,Martinez-Klimov, Mark,Muller, Joseph,Murzin, Dmitry Yu.,Peurla, Markus,Simakova, Irina,Vajglova, Zuzana
, (2022/04/03)
One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60–70 °C under 10–29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71–76% and 72–74% were obtained from citronellal and citral respectively at the contact time 4.2 min, 70 °C and 20 bar. Citral conversion noticeably decreased with time-on-stream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amount of defuctionalization products observed during citral conversion, especially at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepared by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chemical and catalytic properties.
Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine
Korvinson, Kirill A.,Akula, Hari K.,Malinchak, Casina T.,Sebastian, Dellamol,Wei, Wei,Khandaker, Tashrique A.,Andrzejewska, Magdalena R.,Zajc, Barbara,Lakshman, Mahesh K.
supporting information, p. 166 - 176 (2020/01/02)
Facile reduction of aryl halides with a combination of 5% Pd/C, B2(OH)4, and 4-methylmorpholine is reported. Aryl bromides, iodides, and chlorides were efficiently reduced. Aryl dihalides containing two different halogen atoms underwent selective reduction: I over Br and Cl, and Br over Cl. Beyond these, aryl triflates were efficiently reduced. This combination was broadly general, effectuating reductions of benzylic halides and ethers, alkenes, alkynes, aldehydes, and azides, as well as for N-Cbz deprotection. A cyano group was unaffected, but a nitro group and a ketone underwent reduction to a low extent. When B2(OD)4 was used for aryl halide reduction, a significant amount of deuteriation occurred. However, H atom incorporation competed and increased in slower reactions. 4-Methylmorpholine was identified as a possible source of H atoms in this, but a combination of only 4-methylmorpholine and Pd/C did not result in reduction. Hydrogen gas has been observed to form with this reagent combination. Experiments aimed at understanding the chemistry led to the proposal of a plausible mechanism and to the identification of N,N-bis(methyl-d3)pyridin-4-amine (DMAP-d6) and B2(OD)4 as an effective combination for full aromatic deuteriation. (Figure presented.).
