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.
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.
