Methyl vinyl ketone is a widely used organic compound classified as an enone (i.e., an alkene and a ketone). This enone characteristic allows it to undergo a wide variety of chemical reactions, a lot centered around the fact that it can act as a Michael acceptor. MVK is colorless liquid at room temperature with a distinctive and pungent odor. Methyl vinyl ketone has good solubility in polar and polar organics solvents alike (e.g., alcohols, low MW ketones and acids).
Pertinent physical and document information for methyl vinyl ketone are listed below:
Alternate names: buten-3-one; 3-butenone; MVK
CAS number: 78-94-4
Molecular formula: C4H6O
Molar mass: 70.09 g/mol
Density: 0.8407 g/cm3
Melting point: -7 oC
Boiling point: 81.4 oC
Methyl vinyl ketone is prepared both on a lab and industrial scale via different routes. Industrially, it is produced by condensation of acetone and formaldehyde with a subsequent dehydration to give good yields of MVK. Typically industrial processes yield 90-97% purity depending on final distillation capability.
Laboratory preparations typically undertake routes that use chemistries that cannot be used on an industrial scale (e.g., very expensive reagents, highly toxic or difficult to handle reagents). A good example for lab production of methyl vinyl ketone is the hydration of vinyl acetylene using mercury (II) salts. Here the use of mercuric salts on a large scale would be very difficult because of potential toxicity during use and subsequent disposal of by products. A better route is the dehydration of 4-hydroxybutan-2-one using an organic or mild inorganic acid. The difficulty here is the cost of the starting ketone versus the materials used in a typical industrial preparation for MVK.
Arguably the best lab preparation for synthesizing methyl vinyl ketone is use of the Mannich reaction akin to the industrial process, using a dialkylamine hydrochloride to produce a beta-amino salt that can eliminate during heating to create the final MVK molecule.
When producing, handling or otherwise using methyl vinyl ketones I would strongly recommend reading all the pertinent safety information. A brief review of an MSDS is not sufficient for a molecules such as this. One of the primary functions of methyl vinyl ketone is that of an alkylating agent, which is probably it’s biggest safety concern. It is classified as UN1251 by US DOT shipping protocols and is considered a severe inhalation hazard (PIH). Although no documented exposure levels are available, the EPA has determined that both acute and chronic exposures are potentially fatal. MVK can also polymerize spontaneously, with an exothermic behavior that can create secondary toxicity hazards.
Methyl vinyl ketone has many great uses in organic synthesis and there are many good methods to produce this material. Nonetheless, all users should make themselves very familiar with safety hazards and suitable personal protective equipment when using MVK.