2610-40-4

Upstream product

• 30467-62-0 3,3,5,5-tetramethyl-3,5-dihydro-4H-pyrazol-4-one 
• 933-52-8 2,2,4,4-tetramethyl-1,3-cyclobutanedione 
• 1000-87-9 2,4-dimethyl-2,3-pentadiene 
• 598-26-5 dimethylketene 

Relevant academic research and scientific papers

Flash vacuum pyrolysis and photolysis of 3,3,5,5-tetramethylpyrazolin-4- one - A matrix isolation study

The flash vacuum pyrolysis of 3,3,5,5-tetramethylpyrazolin-4-one (4) with subsequent trapping of the products in argon at 10 K results in the formation of a complex product mixture with tetramethylcyclopropanone (5) as one of the minor constituents. The 193 nm photochemistry of matrix-isolated 4 is much cleaner, yielding cyclopropanone 5 and allene oxide 9 as the major products. The reaction of tetramethylallene 13 with oxygen atoms yields the same product mixture of 5 and 9 and thus provides an independent route to these species. The experimental IR spectra of 5 and 9 are in good agreement with the results from DFT calculations.

Fourier Transform Infrared Kinetic Study of the Thermal Decompositon of Tetramethyl-1,3-cyclobutanedione and Dimethylketene

The vapor phase thermolysis of tetramethyl-1,3-cyclobutanedione (TMCBD) has been studied in the temperature range 383-430 degree by Fourier transform infrared spectroscopy.The first order decay constant is log (k1/s-1)=13.78-(48400 cal mol-1/2.303 RT).The decomposition of TMCBD leads exclusively to dimethylketene (DMK) whose buildup and subsequent decay were also followed kinetically.Studied at higher temperatures (450-520 degree), a first order decay constant of log (k2/s-1)=10.72-(48800 mol-1/2.303 RT) was determined for the thermal decomposition of DMK.Rates of decomposition of TMCBD and the corresponding cyclobutanone are compared and shown to be consistent with a twisted quasizwitterionic transition state.Long time (2 h) pyrolysis of TMCBD leads to tetramethylethylene and isopropenyl isopropyl ketone products but no DMK.These observations are rationalised by the scheme involving formation of tetramethylcyclopropanone (TMCP) from DMK and dimethylmethylene radicals, followed by decay of TMCP to the observed products.