926-05-6Relevant articles and documents
Kinetics and products of the reactions of oh radicals with 4,4-dimethyl-1-pentene and 3,3-dimethylbutanal at 296 ± 2 k
Aschmann, Sara M.,Arey, Janet,Atkinson, Roger
experimental part, p. 5810 - 5816 (2010/09/06)
Using a relative rate method, rate constants have been measured for the reactions of OH radicals with 4,4-dimethyl-1-pentene [(CH3) 3CCH2CH=CH2] and its major reaction product, 3,3-dimethylbutanal [(CH3)3CCH2CHO], at 296 ± 2 K and atmospheric pressure of air. The rate constants obtained were 2.41 × 10-11 and 2.73 × 10-11 cm3 molecule-1 s-1, respectively, with estimated uncertainties of ±10%. The products identified and quantified by gas chromatography with mass spectrometry and/or flame ionization detection from the 4,4-dimethyl-1-pentene reaction were acrolein [CH2=CHCHO], 3,3-dimethylbutanal, and a molecular weight 112 carbonyl attributed to 4,4-dimethyl-2-pentenal [(CH3)3CCH=CHCHO], with formation yields of 2.7 ± 0.5%, 59 ± 6%, and 3.4 ± 0.6%, respectively. Using direct air sampling atmospheric pressure ionization mass spectrometry, additional products of molecular weight 146, 177, and 193 were observed, and on the basis of expected reaction schemes these are attributed to the dihydroxycarbonyl HOCH2C(CH3)2CH 2C(O)CH2OH, the hydroxynitrates (CH3) 3CCH2CH(OH)CH2ONO2 and/or (CH 3)3CCH2CH(ONO2)CH2OH, and the dihydroxynitrate O2NOCH2C(CH3) 2CH2CH(OH)CH2OH, respectively. The hydroxynitrates were also tentatively identified by gas chromatography, with a summed yield of ～15%. Acrolein and 4,4-dimethyl-2-pentenal arise from H-atom abstraction from the three equivalent CH3 groups and the 3-position CH2 group, and the sum of their formation yields (6.1 ± 0.8%) is expected to be very close to the fraction of the overall reaction proceeding by H-atom abstraction.
Oxidation of benzylic alcohols and ethers to carbonyl derivatives by nitric acid in dichloromethane
Strazzolini, Paolo,Runcio, Antonio
, p. 526 - 536 (2007/10/03)
Nitric acid in dichloromethane may be successfully employed for the oxidation of benzylic alcohols and ethers to the corresponding carbonyl compounds. The proposed method proved to be of general applicability, affording very good yields of aldehydes and ketones and showing interesting chemoselectivity in many instances, allowing competitive aromatic nitration to be avoided, as well as - in the case of aldehydes - any further oxidation to carboxylic acids. The reaction probably proceeds by a radical mechanism, the active species in the oxidation process being NO2. Competitive formation of nitro esters was observed in some cases, whereas poor results were obtained with allylic and non-benzylic substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Nitric acid in dichloromethane solution. Facile preparation from potassium nitrate and sulfuric acid
Strazzolini, Paolo,Giumanini, Angelo G.,Runcio, Antonio
, p. 1387 - 1389 (2007/10/03)
Pure dry HNO3 can be liberated from KNO3 with 96% H2SO4 directly into CH2Cl2 to yield solutions of variable concentration for use in a number of organic reactions. The present method efficiently replaces the employment of 100% HNO3 in some synthetic applications, avoiding the problems associated in storage and handling the acid.
Selective nitrolytic deprotection of N-BOC-amines and N-BOC-amino acids derivatives
Strazzolini, Paolo,Melloni, Tiziana,Giumanini, Angelo G
, p. 9033 - 9043 (2007/10/03)
The extension of the deprotection procedure using HNO3 in CH2Cl2 to a number of appropriately selected N-BOC-masked amines and derivatives of natural amino acids was investigated. The method was found to work effectively with almost all tested substrates, with the exception of activated aromatic amines and heterocycles which underwent unavoidable faster oxidation. Alanine, phenylalanine, serine and lysine derivatives were efficiently deprotected, as well as dipeptide Ala-Phe, preserving the configuration of the substrates and without affecting copresent Z and ester functions, with a remarkable selectivity towards acid sensitive t-butyl esters. The obtained amino acids esters, isolated and characterized in the form of nitrates salts, proved to be suitable intermediates to be used in peptide synthesis.
Nitrolysis of carboxylic t-butyl and 1-adamantyl esters
Strazzolini, Paolo,Dali'Arche, Maria Grazia,Giumanini, Angelo G.
, p. 9255 - 9258 (2007/10/03)
A cheap, less problematic, efficient and selective reagent for the removal of the t-butyl and 1-adamantyl protecting groups from carboxylic esters was found to be commercial 100% HNO3 in CH2Cl2. Incidentally, 1,1- dimethylethyl nitrate and tricyclo[3.3.1.13,7]dec-1-yl (1-adamantyl) nitrate are coproducts in a clean reaction. The procedure is in many ways superior to the method employing CF3COOH.
Nitrosation of Organic Hydroperoxides by Nitrogen Dioxide/Dinitrogen Tetraoxide
Pryor, William A.,Castle, Laurence,Church, Daniel F.
, p. 211 - 217 (2007/10/02)
Cumyl and tert-butyl hydroperoxides react rapidly with NO2/N2O4 in organic solvents in the presence of a base to form the organic nitrate (RONO2) as the major product, together with smaller amounts of the corresponding nitrite (RONO), alcohol, and carbonyl compound (acetophenone or acetone from cumyl and tert-butyl hydroperoxide, respectively).The products from tert-butyl hydroperoxide are similar whether a base is present or not but those from cumyl hydroperoxide are more complex.We have formulated the initial reaction as a nitrosation of the hydroperoxide by N2O4 to give the pernitrite ester.This latter species is unstable and either rearrenges to give the nitrate or dissociates to form alkoxyl radicals and nitrogen dioxide that ultimately give the other observed products.The kinetics of the reaction were studied by stopped flow and are complex, but we conclude the kinetics are consistent with the nitrosation mechenism.The rate constants at 30 deg C are 2.4*104 and 8.1*103 M-1 s-1 for tert-butyl and cumyl hydroperoxides, respectively.We suggest that this facile reaction of NO2/N2O4 with hydroperoxides may have important consequences respect to the pulmonary toxicity of NO2 in smoggy air.
