- Modeling aqueous-phase hydrodeoxygenation of sorbitol over Pt/SiO 2-Al2O3
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In this paper, we investigated the effects of temperature, hydrogen partial pressure, and sorbitol concentration on the aqueous-phase hydrodeoxygenation (APHDO) of sorbitol over a bifunctional 4 wt% Pt/SiO2-Al 2O3 catalyst in a trickle bed reactor. APHDO involves four fundamental reactions: (1) hydrogenation; (2) dehydration; (3) C-C bond cleavage by dehydrogenation and decarbonylation; and (4) C-C bond cleavage by dehydrogenation and retro-aldol condensation. The main deoxygenation routes are decarbonylation and alcohol dehydration. Retro-aldol condensation plays a critical role in reducing the carbon number of the products. The key products in this system are C1-C6 n-alkanes, primary and secondary alcohols, and carbon dioxide. As shown in this paper, the reaction conditions can dramatically change the product selectivity for APHDO of biomass-derived feedstocks (e.g., sorbitol). A sorbitol hydrodeoxygenation reaction network was generated that predicts all of the 43 experimentally measured species. The reaction network consists of 4804 reactions and produces a total of 1178 distinct chemical species. The associated material balance equations were solved numerically to model the experimentally observed species as a function of temperature, concentration, and pressure. The model concentrations fit well the experimentally measured values, demonstrating that the model was accurately able to model the reaction families and capture the salient features of the experimental observations. The trend observed in this paper can be used for the optimization of reactors and new catalysts to selectively make targeted products by hydrodeoxygenation of biomass-derived feedstocks.
- Moreno, Brian M.,Li, Ning,Lee, Jechan,Huber, George W.,Klein, Michael T.
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- Gas phase and condensed phase SNi reactions. The competitive six and seven centre cyclisations of the 5,6-epoxyhexoxide anion. A joint experimental and ab initio study. A comparison with SNi reactions of homologous epoxyalkoxide anions
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A. Ab initio calculations [at the MP2 Fc/6-31+G(d) level of theory] indicate that the barriers to the transition states for the competitive six and seven centre SNi cyclisation processes of the 5,6-epoxyhexoxide anion are 35.0 and 39.7 kJ mol-1 respectively. Experimental studies show that (i) in solution, the 5,6-epoxyhexoxide anion cyclises (and at the same time opens the ethylene oxide ring) to give tetrahydropyran-2-methanol as the predominant product on workup, and (ii) collisional activation of the 5,6-epoxyhexoxide anion in the gas phase gives the 2-tetrahydropyranmethoxide anion as the exclusive anionic product. It is proposed that frequency factors (Arrhenius A factors) control the courses of these kinetically controlled gas phase reactions. A comparison of the calculated harmonic vibrational partition functions for the two possible transition states confirms a higher value of QVib for the reaction proceeding through the six-membered transition state. B. A comparison is made of the reported competitive SNi reactions for 2,3-epoxypropoxide, 3,4-epoxybutoxide, 4,5-epoxypentoxide and 5,6-epoxyhexoxide anions. For all but the 3,4-epoxybutoxide system, the exclusive or major product is that which contains the smaller of the two ring systems for both gas phase and condensed phase reactions. In the case of the 3,4-epoxybutoxide system: (i) in the gas phase, both four and five membered ring SNi products are formed in comparable yield, and (ii) in the condensed phase, the major product is that with the larger ring.
- Hevko, John M.,Dua, Suresh,Bowie, John H.,Taylor, Mark S.
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- Syn-oxidative cyclizations of trishomoallylic alcohols: Stereoselective and stereospecific synthesis of trans-tetrahydropyranyl alcohols
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Trifluoroacetylperrhenate promotes the hydroxyl-directed syn-oxidative cyclization of trishomoallylic alcohols. The cyclization reaction is highly stereospecific and stereoselective, providing a novel and efficient synthesis of trans-2,6-disubstituted tetrahydropyranyl alcohols.
- McDonald, Frank E.,Singhi, Aatur D.
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- Caprolactam from renewable resources: Catalytic conversion of 5-hydroxymethylfurfural into caprolactone
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Renewable nylon: 5-Hydroxymethylfurfural (HMF), which can be obtained from renewable resources such as D-fructose, was converted into caprolactone with very good overall selectivity in only three steps. The new route involves two hydrogenation steps to obtain 1,6-hexanediol, which was oxidatively cyclized to caprolactone, and then converted into caprolactam. Copyright
- Buntara, Teddy,Noel, Sebastien,Phua, Pim Huat,Melian-Cabrera, Ignacio,De Vries, Johannes G.,Heeres, Hero J.
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- Intramolecular rearrangement of epoxides generated in situ over titanium silicate molecular sieves
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Open chain unsaturated alcohols 1, having the general formula R1R2C=CH(CH2)CR1R2OH (where R1, R2 = H or CH3, and n = 1-3) and carbocyclic unsaturated alcohols of similar type have been efficiently cyclized to the corresponding hydroxytetrahydrofuran or hydroxytetrahydropyran over titanium silicate molecular sieves (TS-1 and Ti-beta), in one pot under mild liquid phase reaction conditions using dilute hydrogen peroxide as oxidant. When the hydroxy nucleophile may attack either of the activated carbon atoms of the epoxides generated in situ, to lead to a derivative of tetrahydrofuran or tetrahydropyran, the former exclusively formed. The regioselectively for such reaction is 100%. When R1 or R2 = CH3, among the diasteroisomeric products trans predominates over cis. In this cyclization reaction titanium silicate epoxidizes the olefin and successively catalyzes the opening of the oxirane ring via intramolecular attack of hydroxy oxygen. Thus the behavior of titanium sites is bifunctional in nature. However, for bicyclic unsaturated alcohols, because of geometric restriction, activity of medium pore TS-1 is very low. Ti-beta synthesized by dry gel conversion has been found to be an efficient catalyst in oxidative cyclization of such bulky organic substrates as α-terpineol, isopulegol, and trans-p-menth-6-ene-2,8-diol to their corresponding tetrahydrofuranols or tetrahydropyranols with a very high regioselectivity.
- Bhaumik, Asim,Tatsumi, Takashi
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- Upgrading biomass-derived furans via acid-catalysis/hydrogenation: The remarkable difference between water and methanol as the solvent
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In methanol 5-hydroxymethylfurfural (HMF) and furfuryl alcohol (FA) can be selectively converted into methyl levulinate via acidcatalysis, whereas in water polymerization dominates. The hydrogenation of HMF, furan and furfural with the exception of FA is
- Hu, Xun,Westerhof, Roel J. M.,Wu, Liping,Dong, Dehua,Li, Chun-Zhu
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- Hydroformylation and hydroalkylcarbonylation of 3,4-dihydro[2H]pyran catalysed by Co2(CO)8 under syngas conditions
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In the cobalt-catalysed hydroformylation of 3,4-dihydro[2H]pyran, the influence of different reaction parameters such as time, pressure, triphenylphosphine addition, catalyst and substrate concentration has been investigated. 2-formyl-tetrahydropyran, tetrahydropyran and a hydroalkylcarbonylation product were the main reaction products. The selectivity towards 2-formyl-tetrahydropyran formation is favoured at constant catalyst and substrate concentration. The coordination of the pyran's oxygen to the cobalt atom seems to be an important intermediate for the formation of 2-formyl-tetrahydropyran. Different substrate or catalyst concentrations promote the formation of other reduced products. The addition of triphenylphosphine to the catalyst leads to a less active species, which decreases the yield and promotes the hydroalkylcarbonylation reaction.
- Arias, Jose L.,Sharma, Pankaj,Cabrera, Armando,Beristain, Fernando,Sampere, Rafael,Arizmendi, Cesar
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- Highly efficient and regioselective cyclization catalyzed by titanium silicate-1
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Highly regioselective cyclization of 3,4, 4,5 and 5,6 unsaturated alcohols to tetrahydrofuranols and tetrahydropyranols is reported using the TS-1-H2O2 system for the first time.
- Bhaumik, Asim,Tatsumi, Takashi
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- Rhenium-catalyzed deoxydehydration of renewable triols derived from sugars
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An efficient method for the catalytic deoxydehydration of renewable triols, including those obtained from 5-HMF, is described. The corresponding unsaturated alcohols were obtained in good yields using simple rhenium(vii)oxide under neat conditions and ambient atmosphere at 165 °C.
- Wozniak, Bartosz,Li, Yuehui,Tin, Sergey,De Vries, Johannes G.
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- Primary Anion–π Catalysis of Epoxide-Opening Ether Cyclization into Rings of Different Sizes: Access to New Reactivity
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The concept of anion–π catalysis focuses on the stabilization of anionic transition states on aromatic π surfaces. Recently, we demonstrated the occurrence of epoxide-opening ether cyclizations on aromatic π surfaces. Although the reaction proceeded through unconventional mechanisms, the obtained products are the same as those from conventional Br?nsted acid catalysis, and in agreement with the Baldwin selectivity rules. Different mechanisms, however, should ultimately lead to new products, a promise anion–π catalysis has been reluctant to live up to. Herein, we report non-trivial reactions that work with anion–π catalysis, but not with Br?nsted acids, under comparable conditions. Namely, we show that the anion–π templated autocatalysis and epoxide opening with alcoholate–π interactions can provide access to unconventional ring chemistry. For smaller rings, anion–π catalysis affords anti-Baldwin oxolanes, 2-oxabicyclo[3.3.0]octanes, and the expansion of Baldwin oxetanes by methyl migration. For larger rings, anion–π templated autocatalysis is thought to alleviate the entropic penalty of folding to enable disfavored anti-Baldwin cyclizations into oxepanes and oxocanes.
- Matile, Stefan,Paraja, Miguel
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p. 6273 - 6277
(2020/02/28)
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- PROCESS FOR PRODUCING 1,6-HEXANEDIOL
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Disclosed herein are processes for producing 1,6-hexanediol. In one embodiment, the process comprises a step of contacting 3,4-dihydro-2H-pyran-2-carbaldehyde, a solvent, and hydrogen in the presence of a catalyst at a reaction temperature between about 0° C. and about 120° C. at a pressure and for a reaction time sufficient to form a product mixture comprising 1,6-hexanediol. In one embodiment, the catalyst comprises a metal M1, a metal M2 or an oxide of M2, and a support, wherein M1 is Rh, Ir, Ni, Pd, or Pt, and M2 is Mo, W, or Re; or M1 is Cu and M2 is Ni, Mn, or W.
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Page/Page column 0093; 0094
(2016/06/28)
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- Simultaneous hydrogenation and acid-catalyzed conversion of the biomass-derived furans in solvents with distinct polarities
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Furfural and 5-hydroxymethylfurfural (HMF), the two typical biomass-derived furans, can be converted into biofuels and value-added chemicals via hydrogenation or acid catalysis or both. The potential competition between the hydrogenation and the catalyzed-conversion of HMF and furfural has been investigated with Pd/C and Amberlyst 70 as the catalysts at 170°C in various solvents. In water, the hydrogenation of HMF or the derivatives of HMF could take place, but the acid-catalyzed conversion of HMF to the diketones (2,5-hexanedione) was the dominant reaction pathway. On the contrary, with ethanol as the solvent, the full hydrogenation of HMF to 2,5-tetrahydrofurandimethanol was the dominant route, and the acid-catalyzed routes became insignificant. The efficiency for hydrogenation of HMF was much higher in ethanol than in water. As for furfural, its hydrogenation proceeded more efficiently in the polar solvents (i.e. ethanol, diethyl ether) than in non-polar solvents (i.e. toluene): a polar solvent tended to favor the hydrogenation of the furan ring in furfural over that of the carbonyl group in the same furfural.
- Hu, Xun,Kadarwati, Sri,Song, Yao,Li, Chun-Zhu
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p. 4647 - 4656
(2016/01/29)
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- PRODUCTION OF TETRAHYDROFURAN-2, 5-DIMETHANOL FROM ISOSORBIDE
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Disclosed herein are processes comprising contacting isosorbide with hydrogen in the presence of a first hydrogenation catalyst to form a first product mixture comprising tetrahydrofuran-2, 5-dimethanol. The processes can further comprise heating the first product mixture in the presence of hydrogen and a second hydrogenation catalyst to form a second product mixture comprising 1,6-hexanediol. The first and second hydrogenation catalysts can be the same or different.
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Page/Page column 28-29
(2013/07/19)
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- PROCESS FOR PREPARING 1, 6-HEXANEDIOL
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Disclosed are processes for preparing 1, 6-hexanediol and synthetic intermediates useful in the production of 1, 6-hexanediol from renewable biosources. In one embodiment, a process comprises contacting levoglucosenone with hydrogen in the presence of a first hydrogenation catalyst at a first temperature to form product mixture (I); and heating product mixture (I) in the presence of hydrogen and a second hydrogenation catalyst at a second temperature to form product mixture (II) which comprises 1, 6-hexanediol.
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(2013/07/19)
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- PROCESS FOR THE PRODUCTION OF HEXANEDIOLS
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Disclosed are processes for preparing 1,2-cyclohexanediol, and mixtures of 1,2-cyclohexanediol and 1,6-hexanediol, by hydrogenating 1,2,6 hexanetriol.
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Page/Page column 25-27
(2013/07/19)
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- PREPARATION OF CAPROLACTONE, CAPROLACTAM, 2,5-TETRAHYDROFURAN-DIMETHANOL, 1,6-HEXANEDIOL OR 1,2,6-HEXANETRIOL FROM 5-HYDROXYMETHYL-2-FURFURALDEHYDE
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The present invention relates to a method for preparing caprolactone, comprising converting 5-hydroxymethyl-2-furfuraldehyde by hydrogenation into at least one intermediate compound selected from the group of 2,5-tetrahydrofuran-dimethanol, 1,6-hexanediol and 1,2,6-hexanetriol,and preparing caprolactone from said intermediate compound. Further, the invention relates to a method for preparing 1,2,6-hexanetriol comprising preparing 5-hydroxymethyl-2-furfaldehyde from a renewable source, converting 5- hydroxymethyl-2-furfaldehyde into 2,5-tetrahydrofuran-dimethanol and converting 2,5-tetrahydrofuran-dimethanol into 1,2,6-hexanetriol. Further, the invention relates to a method for preparing 1,6-hexanediol from 1,2,6- hexanetriol, wherein 1,2,6-hexanetriol is subjected to a ring closure reaction, thereby forming (tetrahydro-2H-pyran-2-yl)methanol, and the (tetrahydro-2H-pyran-2- yl)methanol is hydrogenated, thereby forming 1,6-hexane diol.
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(2011/12/14)
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- Preparation of caprolactone, caprolactam, 2,5-tetrahydrofuran dimethanol, 1,6-hexanediol or 1,2,6-hexanetriol from 5-hydroxymethyl-2-furfuraldehyde
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The present invention relates to a method for preparing caprolactone, comprising converting 5-hydroxymethyl-2-furfuraldehyde by hydrogenation into at least one intermediate compound selected from the group of 2,5-tetrahydrofuran dimethanol, 1,6-hexanediol and 1,2,6-hexanetriol,and preparing caprolactone from said intermediate compound. Further, the invention relates to a method for preparing 1,2,6 hexanetriol comprising preparing 5-hydroxymethyl-2-furfaldehyde from a renewable source, converting 5-hydroxymethyl-2-furfaldehyde into 2,5-tetrahydrofuran dimethanol and converting 2,5-tetrahydrofuran dimethanol into 1,2,6 hexanetriol. Further, the invention relates to a method for preparing 1,6 hexanediol from 1,2,6-hexanetriol, wherein 1,2,6-hexanetriol is subjected to a ring closure reaction, thereby forming 2-hydropyranyl-methanol, and the 2-hydropyranyl-methanol is hydrogenated, thereby forming 1,6 hexane diol.
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Page/Page column 11
(2011/12/12)
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- A mild and efficient method for the selective deprotection of silyl ethers using KF in the presence of tetraethylene glycol
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A mild and efficient protocol for the deprotection of silyl ethers using KF in tetraethylene glycol is reported. A wide range of alcoholic silyl ethers can be selectively cleaved in high yield in the presence of certain acid- and base-labile functional groups. Moreover, the phenolic silyl ethers were cleaved exclusively, without affecting the alcoholic silyl ethers, at room temperature. The Royal Society of Chemistry 2011.
- Yan, Hailong,Oh, Joong-Suk,Song, Choong Eui
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supporting information; experimental part
p. 8119 - 8121
(2012/01/04)
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- A new solid-phase reaction system utilizing a temperature-responsive catalyst: Oxidative cyclization with hydrogen peroxide
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A switchable catalyst based on temperature change provides a novel solid-phase reaction system in water. An increase in catalyst affinity for organic substrates at higher temperature led to efficient activity driving the solid inner-phase reaction, and loss of affinity at lower temperature allowed easy separation of organic products upon completion of the reaction. Application of this catalyst intelligence to design a novel catalytic system brought about an efficient oxidative cyclization with hydrogen peroxide, a useful method of accessing oxygen heterocycles.
- Hamamoto, Hiromi,Suzuki, Yachiyo,Takahashi, Hideyo,Ikegami, Shiro
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p. 2685 - 2689
(2008/09/20)
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- Neighbouring Hydroxy Group Participation in the acid-catalyzed Reaction of Pentane-1,4-diol and -1,2,5-triol and Hexane-1,5-diol and -1,2,6-triol
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Rate constants have been determined and product analysis made for the acid-catalysed reaction in aqueous solution of ω-primary-secondary polyols HO(CH2)nCHOHX; n = 3 or 4, X = CH3 or CH2OH.The pentane series, n = 3, give five membered cyclic ethers, O-5 ethers in > 90percent yield, while the hexane series, n = 4, give O-6 ethers in ca.35 to 40percent yield.For the pentane series it is known that the cyclisation results from reaction at the hindered primary reaction site, and it is shown here that this is occuring with anchimeric assistance.For the hexane series inter- andintramolecular processes are competitive and anchimeric assistance is slight or absent, while cyclisation at the secondary as well as the pimary reaction site is feasible.It is proposed that neighbouring hydroxy group participation in the reaction of all these polyols is a concerted process.
- Herlihy, Kevin P.,Sagatys, Dalius S.
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p. 501 - 524
(2007/10/03)
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- ORGANOTINS AS ETHERIFICATION CATALYSTS. III. ETHERIFICATIONS AND HYDRO-HYDROXY-ELIMINATIONS PROMOTED BY BUTYLTIN TRICHLORIDE
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Butyltin trichloride, as a catalyst precursor, promotes the following processes: (i) etherification of 2,3-unsaturated alcohols, (ii) etherification of functional diols, (iii) cyclization of 2,5-hexanedione, and (iv) dehydration of cyclic diols.Many examples are reported.
- Marton, Daniele,Slaviero, Pierangelo,Tagliavini, Giuseppe
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p. 7099 - 7108
(2007/10/02)
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- Reactions of 6,8-Dioxabicyclo(3.2.1)oct-3-ene and 6,8-Dioxabicyclo(3.2.1)oct-2-ene with Lithium Aluminium Hydride
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Reduction of 6,8-dioxabicyclo(3.2.1)oct-3-ene (6) with lithium aluminium hydride in refluxing 1,2-dimethoxyethane gives 2-hydroxymethyl-3,4-dihydro-2H-pyran (7) in an excellent yield.However, under identical conditions 6,8-dioxabicyclo(3.2.1)oct-2-ene (8) gives a mixture of 4-hexen-1-ol (9), 5-hexen-1-ol (10) and 2-hexene-1,6-diol (11).When 6 is refluxed with LAH in di-n-propyl ether, 7 is obtained in addition to 2-hydroxymethyl-2,3-dihydro-6H-pyran (33).However, compound 8 remains unaffected by LAH under similar conditions.
- Majumdar, K. C.,Ranganayakulu, K.,Brown, R. K.
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p. 303 - 306
(2007/10/02)
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- A Convenient One-step Preparation of Oxacyclanes by Dehydration of Diols over Alumina
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Dehydration of 1,4-, 1,5-, or 1,6- alkanediols over alumina at 220-250 deg C in a distillation apparatus gave the corresponding 5- to 7-membered oxacyclanes in good yield of 51-71percent.Diethylene glycol also gave 1,4-dioxane in 49percent yield, whereas attempted one-step synthesis of crown ethers from polyethylene glycols in a similar manner resulted in the predominant formation of 1,4-dioxane without any trace of crown ether.
- Inoue, Yoshihisa,Deguchi, Shokichiro,Hakushi, Tadao
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p. 3031 - 3032
(2007/10/02)
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