2-Methylbut-3-yn-2-ol

2-Methylbut-3-yn-2-ol is the organic compound with the formula HC2C(OH)Me2 (Me = CH3). A colorless liquid, it is classified as an alkynyl alcohol.

2-Methylbut-3-yn-2-ol
Names
Other names
  • Ethynylmethylcarbinol
  • Dimethylethynylcarbinol
  • 1,1-Dimethyl-2-propyn-1-ol
  • Dimethylethynylmethanol
  • MB
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.003.700
EC Number
  • 204-070-5
RTECS number
  • ES0810000
UNII
UN number 1987
Properties
C5H8O
Molar mass 84.118 g·mol−1
Appearance Colorless liquid
Density 0.8637 g/cm3
Melting point 3 °C (37 °F; 276 K)
Boiling point 104 °C (219 °F; 377 K)
good
Hazards
GHS pictograms
GHS Signal word Danger
H225, H226, H302, H315, H318, H319, H335, H361
P201, P202, P210, P233, P240, P241, P242, P243, P261, P264, P270, P271, P280, P281, P301+312, P302+352, P303+361+353, P304+340, P305+351+338, P308+313, P310, P312, P321, P330, P332+313
Flash point 20 °C (68 °F; 293 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Preparation and use

It arises from the condensation of acetylene and acetone. The addition can be promoted with base[1] or with Lewis acid catalysts.[2] 2-Methylbut-3-yn-2-ol is produced on an industrial scale as a precursor to terpenes and terpenoids.

2-Methylbut-3-yn-2-ol is an intermediate in this industrial route to geraniol.[3]

2-Methylbut-3-yn-2-ol also is used as a monoprotected version of acetylene. For example, after arylation at carbon, the acetone can be removed with base:[4]

HC2C(OH)Me2 + ArX + base → ArC2C(OH)Me2 + [Hbase]X
ArC2C(OH)Me2 → ArC2H + OCMe2

In this regard, 2-methylbut-3-yn-2-ol is used similarly to trimethylsilylacetylene.

References
  1. Donald D. Coffman (1940). "Dimethylethynylcarbinol". Org. Synth. 20: 40. doi:10.15227/orgsyn.020.0040.
  2. Frantz, Doug E.; Fässler, Roger; Carreira, Erick M. (2000). "Facile Enantioselective Synthesis of Propargylic Alcohols by Direct Addition of Terminal Alkynes to Aldehydes". J. Am. Chem. Soc. 122: 1806-1807. doi:10.1021/ja993838z.
  3. Eberhard Breitmaier (2006). Terpenes: Flavors, Fragrances, Pharmaca, Pheromones. Wiley-VCH. doi:10.1002/9783527609949. ISBN 9783527609949.
  4. Gordon, John (2001). "2-Methylbut-3-yn-2-ol". e-EROS Encyclopedia of Reagents for Organic Synthesis. pp. 1–2. doi:10.1002/047084289X.rm157.
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