609-08-5Relevant articles and documents
Synthesis, Electronic Spectroscopy, and Photochemistry of Methacrolein Oxide: A Four-Carbon Unsaturated Criegee Intermediate from Isoprene Ozonolysis
Vansco, Michael F.,Marchetti, Barbara,Trongsiriwat, Nisalak,Bhagde, Trisha,Wang, Guanghan,Walsh, Patrick J.,Klippenstein, Stephen J.,Lester, Marsha I.
, p. 15058 - 15069 (2019)
Ozonolysis of isoprene, one of the most abundant volatile organic compounds in the earth's atmosphere, generates the four-carbon unsaturated methacrolein oxide (MACR-oxide) Criegee intermediate. The first laboratory synthesis and direct detection of MACR-oxide is achieved through reaction of photolytically generated, resonance-stabilized iodoalkene radicals with oxygen. MACR-oxide is characterized on its first π? a? πelectronic transition using a ground-state depletion method. MACR-oxide exhibits a broad UV-visible spectrum peaked at 380 nm with weak oscillatory structure at long wavelengths ascribed to vibrational resonances. Complementary theory predicts two strong ?€? a? πtransitions arising from extended conjugation across MACR-oxide with overlapping contributions from its four conformers. Electronic promotion to the 11π? state agrees well with experiment, and results in nonadiabatic coupling and prompt release of O 1D products observed as anisotropic velocity-map images. This UV-visible detection scheme will enable study of its unimolecular and bimolecular reactions under thermal conditions of relevance to the atmosphere.
Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)
Condon, Sylvie,Le Gall, Erwan,Pichon, Christophe,Presset, Marc,Xavier, Tania
supporting information, p. 2085 - 2094 (2021/09/02)
The use of mono-substituted malonic acid half oxyesters (SMAHOs) has been hampered by the sporadic references describing their preparation. An evaluation of different approaches has been achieved, allowing to define the best strategies to introduce diversity on both the malonic position and the ester function. A classical alkylation step of a malonate by an alkyl halide followed by a monosaponification gave access to reagents bearing different substituents at the malonic position, including functionalized derivatives. On the other hand, the development of a monoesterification step of a substituted malonic acid derivative proved to be the best entry for diversity at the ester function, rather than the use of an intermediate Meldrum acid. Both these transformations are characterized by their simplicity and efficiency, allowing a straightforward access to SMAHOs from cheap starting materials.
Preparation method of diethyl methylmalonate by taking heteropolyacid as catalyst
-
Paragraph 0013-0020, (2020/05/01)
The invention relates to a preparation method of diethyl methylmalonate by taking heteropolyacid as a catalyst. The method comprises the following steps: adding 2-cyanopropionic acid into ethanol fordissolving, controlling the molar ratio of 2-cyanopropionic acid to ethanol to be 1:(3-4), and transferring the obtained solution into a reaction kettle after dissolving; stirring at room temperature,adding the heteropolyacid catalyst, controlling the mass ratio of 2-cyanopropionic acid to the heteropolyacid catalyst to be 2:(1-2), controlling the temperature to be 65-80 DEG C, reacting for 3-4 h, and then ending the reaction; distilling to separate ethanol, adding ammonia water to neutralize, regulating the pH value to be neutral, and fractionating to obtain crude diethyl methylmalonate; andputting the crude diethyl methylmalonate into a rectifying tower, and carrying out reduced pressure rectification to obtain diethyl methylmalonate. Sulfuric acid is replaced with the heteropolyacid catalyst for an esterification reaction, so the method has the advantages of good selectivity, high catalytic activity, high regeneration speed and small corrosion to equipment.