@article { ISI:000274449000021, title = {Intramolecular hydrogen abstraction in radicals derived from inositol 1,3-acetals: efficient access to cyclitols}, journal = {European Journal of Organic Chemistry}, number = {4}, year = {2010}, month = {FEB}, pages = {755-764}, publisher = {WILEY-V C H VERLAG GMBH}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

The benzylidene acetals obtained by cleavage of the orthobenzoate moiety in myo-mositol 1,3,5-orthobenzoate were used to prepare mono- as well as di-deoxy inositol derivatives via their xanthates. The dideoxygenation is a result of intramolecular abstraction of the benzylidene acetal hydrogen and subsequent cleavage of the acetal ring. Such a cleavage does not take place in analogous acetals derived from other orthoesters. The 1,3-acetals derived from myoinositol 1,3,5-orthoesters were also used to prepare neo-inositol and isomeric deoxy-amino inositols, Most of the reactions in these synthetic sequences starting from myo-inositol give one product in each step. The results presented here show that myo-inositol 1,3,5-orthobenzoate offers many advantages over other orthoesters for the synthesis of cyclitol derivatives from myo-inositol.

}, keywords = {cyclitols, Deoxygenation, Inosamine, Inositol, Radical reactions, Radicals, Xanthate}, issn = {1434-193X}, doi = {10.1002/ejoc.200901156}, author = {Murali, Chebrolu and Gurale, Bharat P. and Shashidhar, Mysore S.} } @article { ISI:000294593400012, title = {Thermal epimerization of inositol 1,3-benzylidene acetals in the molten state}, journal = {Tetrahedron}, volume = {67}, number = {38}, year = {2011}, month = {SEP}, pages = {7280-7288}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

1,3-O-Benzylidene-2,4,5,6-tetra-O-substituted-myo-inositol derivatives obtained by the DIBAL-H reduction of the corresponding myo-inositol 1,3,5-orthobenzoate derivatives undergo epimerization at the acetal carbon on heating, in the molten state, just above their melting point. The same epimerization reaction does not proceed either in the crystalline state or in solution. DFT calculations suggest that the epimeric acetal obtained by this thermal process is relatively more stable than the starting acetal. Either of these acetals could not be obtained by the reaction of the corresponding inositol derived diol with benzaldehyde. These observations constitute a novel reaction solely in the molten state, which are rarely encountered in the literature. X-ray crystal structures of the epimeric acetals as well as their radical deoxygenation reaction are also reported. (C) 2011 Elsevier Ltd. All rights reserved.

}, keywords = {cyclitols, Deoxygenation, Epimerization, Melt, Xanthate}, issn = {0040-4020}, doi = {10.1016/j.tet.2011.07.044}, author = {Gurale, Bharat P. and Krishnaswamy, Shobhana and Vanka, Kumar and Shashidhar, Mysore S.} } @article { ISI:000299911600015, title = {Challenges and opportunities in biofuels production}, journal = {Indian Journal of Chemistry Section A-Inorganic Bio-Inorganic Physical Theoretical \& Analytical Chemistry}, volume = {51}, number = {1-2}, year = {2012}, month = {JAN}, pages = {174-185}, publisher = {NATL INST SCIENCE COMMUNICATION-NISCAIR}, address = {DR K S KRISHNAN MARG, PUSA CAMPUS, NEW DELHI 110 012, INDIA}, abstract = {

Biofuels are attractive alternative to petroleum diesel. They are renewable, non-toxic, biodegradable, carbon neutral and lead to reduced tailpipe emissions. This article presents the current state-of-art processes of their production and discusses the opportunities and future challenges in this area of research.

}, keywords = {Biodiesel, biofuels, Deoxygenation, Hydrotreatment, Renewable fuels, Solid catalysts, Transesterification (fatty acid glycerides), Vegetable oils/fats}, issn = {0376-4710}, author = {Srinivas, Darbha and Satyarthi, Jitendra Kumar} } @article { ISI:000301128300003, title = {Radical mediated deoxygenation of inositol benzylidene acetals: conformational analysis, DFT calculations, and mechanism}, journal = {Carbohydrate Research}, volume = {351}, year = {2012}, month = {APR}, pages = {26-34}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Xanthates of 1,3-benzylidene acetal derivatives of myo- and neo-inositols undergo dideoxygenation under Barton-McCombie conditions, as a result of intramolecular abstraction of the benzylidene acetal hydrogen and subsequent cleavage of the acetal ring. Scrutiny of structure of these bicyclic inositol derivatives shows that although the conformation of the two rings can vary depending on the configuration of the inositol ring and the phase in which the molecules are present, both the xanthates lead to the formation of the same dideoxyinositol. DFT calculations on these molecular systems suggest that neo-inositol derivatives undergo conformational change prior to radical formation while myo- inositol derivatives undergo conformational change subsequent to radical formation, during the deoxygenation reaction. A low barrier for intramolecular hydrogen transfer supports the extreme facility of this deoxygenation reaction. (C) 2012 Elsevier Ltd. All rights reserved.

}, keywords = {Deoxygenation, DFT, Inositol, Mechanism, Radical, Xanthate}, issn = {0008-6215}, doi = {10.1016/j.carres.2012.01.001}, author = {Gurale, Bharat P. and Vanka, Kumar and Shashidhar, Mysore S.} } @article { ISI:000374626200017, title = {Catalytic decarboxylation of non-edible oils over three-dimensional, mesoporous silica-supported Pd}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {417}, year = {2016}, month = {JUN}, pages = {126-134}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Deoxygenation of fatty acids (oleic and stearic acids) and non-edible oil (jatropha oil) over Pd(1-5 wt\%) supported on two structurally different, three-dimensional, mesoporous silica (SBA-12 and SBA-16) catalysts was investigated. Pd/SBA-16 (cubic mesoporous structure with space group Im (3) over barm) showed higher catalytic activity than Pd/SBA-12 (hexagonal mesoporous structure with space group p6(3)/mmc). The influence of reaction parameters like temperature, H-2 pressure and Pd content as well as the nature of the feedstock on catalytic activity and product selectivity was studied. A temperature of above 320 degrees C, reaction time of 5 h and Pd content (on silica surface) of 3 wt\% enabled complete conversion of the fatty compounds into diesel-range hydrocarbons. Deoxygenation proceeded through hydrodeoxygenation and decarboxylation mechanisms when a saturated (stearic) acid was used as a feed while it advanced mainly through decarboxylation route when an unsaturated (oleic) acid was employed. Higher surface hydrophobicity and smaller size particles of Pd are the possible causes for the superior catalytic activity of Pd/SBA-16. (C) 2016 Elsevier B.V. All rights reserved.

}, keywords = {Biofuel, Deoxygenation, Diesel-range hydrocarbons, Mesoporous silica, Supported palladium, Vegetable oil}, issn = {1381-1169}, doi = {10.1016/j.molcata.2016.03.023}, author = {Raut, Ravindra and Banakar, Vikram V. and Darbha, Srinivas} } @article {45737, title = {Promotional effect of WOx in Pt-WOx/AlPO4-5 catalyzed deoxygenation of fatty acids}, journal = {ChemistrySelect}, volume = {2}, year = {2017}, month = {FEB}, pages = {1895-1901}, type = {Article}, abstract = {

WOx promoted Pt/AlPO4-5 catalysts with varying Pt and W contents were prepared by wet-impregnation method and characterized. Catalysts with Pt to W weight ratio of 1: 2 exhibited higher catalytic performance than the other compositions in deoxygenation of oleic acid (OA). WOx enhanced significantly the catalytic activity of Pt and enabled quantitative conversion of OA to linear alkanes (predominantly C-18/C-17) at a temperature as low as 280 degrees C. It changed the reaction pathway from decarbonylation/ decarboxylation (DCO for Pt/AlPO4-5) to hydrodeoxygenation (HDO for Pt-WOx/AlPO4-5). It affected the particle size and redox behaviour of Pt. The enhanced H-spill over (by 14.8\%) and presence of strong acid sites (300 - 500 degrees C) are the cause for the high activity of Pt-WOx/AlPO4-5 catalysts even at lower temperatures. Partially reduced WOx activates OA and leads to the HDO product (C-18). In the absence of WOx, Lewis acid sites of the support activate OA through the C=O group and Pt facilitates C-C cleavage and formation of DCO product (C-17).

}, keywords = {biofuels, Deoxygenation, Fatty acids, Green Diesel, Hydrocarbons}, issn = {2365-6549}, doi = {10.1002/slct.201700159}, author = {Janampelli, Sagar and Darbha, Srinivas} } @article {43966, title = {Selective and reusable Pt-WO x /Al 2 O 3 catalyst for deoxygenation of fatty acids and their esters to diesel-range hydrocarbons}, journal = {Catalysis Today}, volume = {309}, year = {2017}, month = {JUN}, pages = {219-226}, type = {Article}, abstract = {Tungsten oxide promoted platinum catalysts (Pt-WOx/Al2O3) of varying composition were prepared by wet impregnation method and reduced in hydrogen atmosphere. X-ray powder diffraction and photoelectron spectroscopy revealed that Pt is completely reduced to metallic state while tungsten is in +6 and +5 oxidation state. Pt crystallite and particle sizes increased (from 1.2 to 1.4 nm and 2.5 to 3 nm, respectively) in presence of WOx (CO-chemisorption and transmission electron microscopy). Tungsten addition augmented strong acid sites. It enhanced significantly the catalytic activity of Pt/Al2O3 in deoxygenation of fatty acids and their methyl esters. Tungsten altered the reaction pathway from decarbonylation/decarboxylation to hydrodeoxygenation. A catalyst with 4 wt\% Pt and 8 wt\% W exhibited high catalytic performance. Complete conversion of oleic acid and octadecane product selectivity in the range 67.1 - 80.8\% was obtained. Pt-WOx/Al2O3 is a stable and reusable fatty acid deoxygenation catalyst.}, keywords = {biofuels, Deoxygenation, Diesel-range hydrocarbons, Fatty acids, Pt catalyst}, issn = {0920-5861}, doi = {10.1016/j.cattod.2017.06.030}, author = {Janampelli, Sagar and Srinivas, Darbha} } @article {46011, title = {Hydrodeoxygenation of vegetable oils and fatty acids over different group VIII metal catalysts for producing biofuels}, journal = {Catalysis Surveys From Asia}, volume = {23}, year = {2019}, month = {JUN}, pages = {90-101}, type = {Article}, abstract = {

Energy security and environment protection are two important aspects of sustainable development. Biofuels are renewable and carbon neutral. They are suitable replacement for conventional fossil derived transport fuels. Their use leads to sustainable development. Among several technological options, catalytic hydrodeoxygenation of vegetable oils leading to diesel-range hydrocarbons is the most attractive approach for producing biofuels. The green diesel, thus produced, could be blended with petro-diesel or used as standalone fuel in the conventional diesel engines. Our research group has been active in developing efficient solid catalysts for hydroprocessing of vegetable oils. This account presents some of our efforts using supported group VIII metals and the importance of electronic contact between metal and support on the catalytic activity and hydrodeoxygenation selectivity in hydroprocessing of vegetable oils.

}, keywords = {biofuels, Catalysis over group VIII metals, Deoxygenation, Hydroprocessing, Renewable diesel}, issn = {1571-1013}, doi = {10.1007/s10563-019-09266-4}, author = {Janampelli, Sagar and Darbha, Srinivas} }