91555-76-9Relevant academic research and scientific papers
Selective acetylation of primary alcohols by ethyl acetate
Singha, Raju,Ray, Jayanta K.
, p. 5395 - 5398 (2016/11/11)
A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
DDQ catalyzed benzylic acetoxylation of arylalkanes: a case of exquisitely controlled oxidation under sonochemical activation
Kumar, Vinod,Sharma, Abhishek,Sharma, Meenakshi,Sharma, Upendra K.,Sinha, Arun K.
, p. 9718 - 9723 (2008/02/12)
Acetoxylated arylalkanes are selectively obtained via sonochemical activation of DDQ catalyzed benzylic oxidation of arylalkanes in the presence of anhydrous acetic acid. The method gives an exquisite control of benzylic acetoxylation under ultrasound, in contrast to the uncontrolled oxidation observed under conventional heating or microwave activation. In addition, the developed method could be?a useful strategy for the synthesis of industrially important enantiopure benzyl alcohols due to the easy amenability of obtained acetoxylated products toward chiral resolution.
Spectroscopic and Molecular Mechanics Calculations of Discrimination between Enantiomers Possessing an Electron Rich Aromatic Group Directly Attached to the Chiral Carbon Atom with Optically Pure Benzoyl Derivatives
Jursic, Branko S.
, p. 961 - 970 (2007/10/02)
The discrimination between enantiomers that have a chiral centre directly attached to the electron rich aromatic ring by interactions with optically pure electron deficient aromatic compounds was studied by 1H NMR and molecular mechanics calculations.The enantiomeric spectroscopic discrimination is due to formation of non-bonding interactions which lead to the formation of diastereoisomeric complexes.The calculated HOMO energy values for electron rich racemic compounds and LUMO values for electron poor resolving agents are in good agreement with the observed chemicalshift differences between enantiomers by 1H NMR.Exceptions to these observations are seen for compounds which possess groups that are in a position to sterically push apart the complexation components and thus decrease the binding energy and diminish the enantiomeric discrimination.The discrimination strongly depends on concentration of the components in the solution, their ratio, temperature and the polarity of the media.Polar racemic compounds show the smallest enantiomeric discrimination by increasing the polarity of the media.For good enantiomeric discrimination both chiral centres must be rigidly bound to the aromatic rings.If the chiral centre is separated from the aromatic ring by flexible bonds the enantiomeric recognition fails despite the formation of strong non-bonding interactions.The binding energies calculated by AMBER and MM + force fields are relatively weak (ca. 2 kcal mol-1) suggesting that only a small portion of the molecules in solution are incorporated into the complexes.Our attempt to provide evidence for selective binding of only one enantiomer to the template molecule was unsuccessful.Neverthelessour results support the formation of inter-exchangeable diastereomeric complexes.Although it might be argued that two sets of signals should also be obtained for the template molecule, all our 1H NMR spectra show only one set of signals for the optically pure template and two sets of signals for the racemic component in their chloroform solutions.Despite low binding energies enantiomeric discrimination with strong electron accepting resolving agents can be achieved in as low as 0.01 mol dm-3 chloroform solution.
The Reactions of Lignin with Alkaline Hydrogen Peroxide. Part III. The Oxidation of Conjugated Carbonyl Structures
Gellerstedt, Goeran,Agnemo, Roland
, p. 275 - 280 (2007/10/02)
The alkaline hydrogen peroxide oxidation of aryl-α-carbonyl structures and cinnamaldehyde structures related to lignin has been studied using a kinetic method.Aryl-α-carbonyl structures in phenolic units are quantitatively cleaved to form the corresponding hydroquinone derivatives with rates of reaction strongly dependent on the substitution pattern in the aromatic ring.The presence of heavy metal ions like Fe(III) or Mn(IV) accelerates the oxidation but decreases the yield of hydroquinone.In nonphenolic units the oxidation of aryl-α-carbonyl structures is dependent upon the structure of the side chain.Cinnamaldehyde structures of the coniferaldehyde type are readily cleaved by alkaline hydrogen peroxide giving rise to the corresponding aromatic aldehyde.The reaction shows a first-order dependency on 2-> whereas -> has a negligible influence within the pH range studied.The significance of these results for the bleaching of mechanical pulps with alkaline hydrogen peroxide is briefly discussed.
