4-Methyl-3-pentene-2-one

An unfavorable methyl-methyl interaction destabilizes the s-trans conformation of 4-methyl-3-penten-2-one relative to the s-cis conformation, and the equilibrium favors the s-cis form. 

Chemical Designations - Synonyms Isobutenyl methyl ketone Isopropylideneacetone Methyl isobutenyl ketone 4-Methyl -3-pentene-2-one Chemical Formula CH3COCH=C(CH3)2. Observable Characteristics - Physical State (as shipped) Liquid Color Colorless to slightly yellow Odor. Strong peppermint honeylike. 

Show how you could prepare the following compounds from 4-methyl-3-penten- 2-one, (CH3)2C=CHCOCH3. 

Methyl-3-penten-2-one. See Mesityl oxide Methyl-4-(phenylthio)phenyl sulfoxide,... 

Steele, W.V., Chirico, R.D., Cowell, A.B., Knipmeyer, S.E., and Nguyen, A. Thermodynamic properties and ideal-gas enthalpies of formation for 2-aminoisobutyric acid (2-methylalanine), acetic acid, ( -5-ethylidene-2-norbornene, mesityl oxide (4-methyl-3-penten-2-one), 4-methylpent-l-ene, 2,2 -bis(phenylthio)propane, and glycidyl phenyl ether (1,2-epoxy-3-phenox3q>ropane), / Chem. Eng. Data, 42(6) 1053-1066, 1997. 

In general, we use bases to initiate many of the reactions in this chapter. However, acids can catalyze some reactions. Figure 11-36 shows the formation of 4-methyl-3-penten-2-one by acid catalysis. 

Cycloaddition using the unusually functionalized 2-diazo-1,1,1-trifluoro-3-nitropropane (15) could be achieved with methyl acrylate, methacrylic acid chloride, and esters (Scheme 8.5), but not with the 1,2-disubstituted C=C bonds of p-nitrostyrene, ethyl cinnamate, and 4-methyl-3-penten-2-one (42). In these cycloadditions, 15 is considerably less reactive than 2-diazo-1,1,1-trifluoroethane... 

Similarly, the uptake of acetone into sulfuric acid-water solutions has been reported (Duncan et al., 1998), with the formation of 4-methyl-3-penten-2-one and trimethylbenzene at temperatures above 200 K and 75 wt% H2S04. 

MESITYL OXIDE Methyl Isobutenyl ketone, Isopropylideneacetone, 4-Methyl- 3-pentene 2-one Flammable Liquid, III 2 3 0 ... 

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