Ratna Ghosh

Jadavpur University

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B.R. Singh

Indian Institute of Technology Roorkee

Vytas A. Bankaitis

Texas A&M University

J. Konar

Indian Institute of Technology Kharagpur

László von Szentpály

University of Stuttgart

Debasisa Mohanty

National Institute of Immunology

Michael P. Doyle

Agri Food and Biosciences Institute

Cory Momany

University of Georgia

Marvin L. Hackert

The University of Texas at Austin

William R. Winchester

Grand Valley State University

P. Roychowdhury

University of Calcutta

Cooperative Institutions

Indian Institute of Technology Kharagpur

Jadavpur University

Centre National de la Recherche Scientifique

University of Calcutta

Université Paris Cité

Texas A&M University

The University of Texas at Austin

University of the Basque Country

Indian Institute of Technology Indore

University of Salford

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Oxidation of low density polyethylene (LDPE) by purple hydrocarbon

Journal of Applied Polymer Science (1987)

J. Konar Soumen Ghosh A. K. Banthia Ratna Ghosh

Oxidation of Low Density Polyethylene (DPE) By Purple tlydrocarbonIn recent years, a number of heterogeneous methods'-'* have been developed for oxidizing lowdenaity polyethylene (LDPE) and also the polyol& in general.However, these entail mixing problems and result in inhomogeneous oxidation.A homogeneous method, on the other hand, can achieve controlled, uniform, and optimal bulk and surface oridation.The phase W e r catalyste have of late opened the avenue8 for oxidation at specific sites for a wide variety of organic m0lecule4'~-'~ but they have never been applied for polymer modification in homogeneous and biphasic systemg We have developed a new methd for oxidation of polyoleiins which is homogeneous in nature and utilizes a phase t d e r catalyst to transfer the oxidant into the hydrocarbon phase.The present communication describes the preliminary investigation regarding the utility of the "purple hydrocarbon" reagent as an effective homogeneous oxidizing agent for LDPE. Mat8rialaPolyethylene samples were supplied by 1.E.L (Chemicals Division).They contained no commercial additives.All other chemicals like potassium permanganate, sodium chloride, and tetrabutyl ammonium bromide were of analytical grade.The solvents, benzene and toluene, were of spectroecopic quality. PREPARATION OF PURPLE BENZENEPotassium permanganate (5 g) was dissolved in 30 mL of 10% sodium chloride solution (w/w) and a bright colored solution was obtained.To this, 30 mL of benzene was added.This mixture was vigorously stirred and allowed to stand for a brief period.It waa noted that the purple color remained entirely in the aqueous layer.To this, an aqueous solution of tetrabutylammonium bromide (prepared by dissolving 4 g salt in 5 mL of-water) was added, and the mixture was vigorously stirred and allowed to stand.The nonaqueous phase which formed the upper layer turned purple.This mixture was called "purple benzene" and used as the oxidizing agent.In a s i m i h .manner " purple toluene" was also prepared.

Low-density polyethylene

10.1002/app.1987.070340134

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Citations (9)

ChemInform Abstract: Structure of Kopsine: Methyl 3‐Hydroxy‐22‐oxokopsan‐1‐carboxylate

ChemInform (1993)

William Watt Ratna Ghosh Tapan Seal Banibrata Mukherjee

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Carboxylate

10.1002/chin.199317248

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Citations (0)

Protonation thermodynamics of violuric acid

Journal of Inorganic and Nuclear Chemistry (1981)

Beg R. Singh Ratna Ghosh

10.1016/0022-1902(81)80211-4

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Citations (11)

Electronic absorption and fluorescence spectra and excited singlet-state dipole moments of biologically important pyrimidines

Structural Chemistry (1992)

Cyril Párkányi Christian Boniface Jean‐Jacques Aaron Mame Diabou Gaye Ratna Ghosh

CNDO/2

10.1007/bf00672795

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Citations (37)

Crystallographic Structure of a PLP-Dependent Ornithine Decarboxylase fromLactobacillus30a to 3.0 Å Resolution

Journal of Molecular Biology (1995)

Cory Momany S.R. Ernst Ratna Ghosh Ning‐Leh Chang Marvin L. Hackert

Antiparallel (mathematics)

Dodecameric protein

Multiple isomorphous replacement

Linker

Trimer

10.1006/jmbi.1995.0526

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Citations (124)

Full ab Initio Conformational Spectrum of α,α‘-Diaminoacetone

The Journal of Physical Chemistry A (1997)

László von Szentpály Igor L. Shamovsky Ratna Ghosh Marwan Dakkouri

The ab initio conformational spectrum of α,α'-diaminoacetone, (NH2CH2)2CO, is obtained by systematic conformational space search at the HF/6-31+G* level. The 15 conformers are discussed in terms of near-neighbor interactions such as hydrogen bonding. Conformer 1 with a planar heavy-atom structure and two acceptor-bifurcated NH2:::O:::H2N hydrogen bonds is the global minimum at all levels of theory: AM1, HF/STO-3G, HF/6-31G, HF/6-31G*, HF/6-31+G*, HF6-311++G**//HF/6-31+G*, HF/6-311++G(3df, 3pd)//HF/6-31+G*, MP2/6-31+G*//HF/6-31+G*, and MP2/6-311++G**//HF/6-31+G*. The double bifurcation appears to be a novelty in hydrogen bonding. The relative energies of higher conformational states show a distinct basis set dependence. Significantly, HF/6-31G calculations do not reproduce the full HF/6-31+G* conformational spectrum, since the pyramidality of amino nitrogens is clearly underestimated at the former level. The AM1 method predicts far too few minima and does not seem to properly describe the NH···O bond.

Conformational isomerism

Hydrogen atom

10.1021/jp963079w

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Citations (4)

Structure of kopsine: methyl 3-hydroxy-22-oxokopsan-1-carboxylate

Acta Crystallographica Section C Crystal Structure Communications (1993)

William Watt Ratna Ghosh Tapan Seal Banibrata Mukherjee

The Kopsine molecule consists of five fused rings. The phenyl ring A is almost planar. The conformation of ring B is a pure envelope, ring C is a half-chair, ring D is a chair and ring E is a boat. An intramolecular hydrogen bond O(3)-H(O3)...O(1') helps to stable the boat conformation of ring E

Carboxylate

Cyclohexane conformation

Envelope (radar)

10.1107/s0108270192010035

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Citations (3)

Enhanced enantiocontrol in catalytic metal carbene transformations with dirhodium (II) tetrakis[methyl 2‐oxooxazolidin‐4(S)‐carboxylate], Rh₂(4S‐MEOX)₄

Recueil des Travaux Chimiques des Pays-Bas (1995)

Michael P. Doyle Alexey B. Dyatkin Marina Protopopova Chien I. Yang Charla S. Miertschin

Abstract The synthesis, spectral characteristics, and X‐ray structures for dirhodium(II) tetrakis[methyl 2‐oxooxazolidin‐4(S)‐carboxylate], Rh 2 (4S‐MEOX) 4 , and the related dirhodium(II) tetrakis[methyl 5(R)‐methyl‐2‐oxooxazolidin‐4(S)‐carboxylate], Rh 2 (4S‐THREOX) 4 , are reported. Comparison is made between these 2‐oxooxazolidin‐ligated dirhodium(II) catalysts for metal carbene transformations and those with comparable 2‐oxopyrrolidine ligands, especially dirhodium(II) tetrakis[methyl 2‐oxopyrrolidine‐5(S)‐carboxylate], Rh 2 (5S‐MEPY) 4 . Structure‐selectivity comparisons reveal that Rh 2 (4S‐MEOX) 4 provides higher enantiocontrol and, in some cases, higher diastereocontrol than Rh 2 (5S‐MEPY) 4 in intramolecular carbon‐hydrogen insertion reactions of sterically demanding diazoacetates and diazoacetamides and is the catalyst of choice for highly enantioselective diazodecomposition of adamantyl diazoacetates and N‐(tert )butyldiazoacetamides. The structurally analogous Rh 2 (4S‐THREOX) 4 is nearly identical with Rh 2 (4S‐ MEOX) 4 in its overall effect on selectivity. The net advantage of Rh 2 (4S‐MEOX) 4 lies in its wider openness for metal carbene transformations.

Carboxylate

10.1002/recl.19951140407

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Citations (71)

Thermodynamics and Kinetics of Micellization, including Solubilization

Springer eBooks (1991)

R. Palepu M. A. Thomason D. M. Bloor Denver G. Hall W. A. Wan-Bahdi

Micellar solutions

Cationic polymerization

Aggregation number

10.1007/978-1-4615-3836-3_45

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