Pinacol

Last updated
Pinacol
Pinacol-2D-skeletal.png
Pinacol-1-from-xtal-3D-bs-17.png
Names
Preferred IUPAC name
2,3-Dimethylbutane-2,3-diol
Other names
2,3-Dimethyl-2,3-butanediol
Tetramethylethylene glycol
1,1,2,2-Tetramethylethylene glycol
Pinacone
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.849 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 200-933-5
PubChem CID
UNII
  • InChI=1S/C6H14O2/c1-5(2,7)6(3,4)8/h7-8H,1-4H3 Yes check.svgY
    Key: IVDFJHOHABJVEH-UHFFFAOYSA-N Yes check.svgY
  • CC(C)(O)C(C)(C)O
  • CC(C)(O)C(C)(C)O
Properties
C6H14O2
Molar mass 118.174 g/mol
AppearanceWhite solid
Density 0.967 g/cm3
Melting point 40 to 43 °C (104 to 109 °F; 313 to 316 K)
Boiling point 171 to 173 °C (340 to 343 °F; 444 to 446 K)
Hazards
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
Warning
H228, H315, H319, H335
P210, P240, P241, P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P370+P378, P403+P233, P405, P501
Flash point 77 °C (171 °F; 350 K)
Safety data sheet (SDS) External MSDS
Related compounds
Related compounds
Pinacolone
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Pinacol is a branched alcohol which finds use in organic syntheses. It is a diol that has hydroxyl groups on vicinal carbon atoms. A white solid that melts just above room temperature, pinacol is notable for undergoing the pinacol rearrangement in the presence of acid and for being the namesake of the pinacol coupling reaction.

Contents

Preparation

It may be produced by the pinacol coupling reaction from acetone: [1]

Pinacol coupling of acetone.png

Reactions

As a vicinal-diol, it can rearrange to pinacolone by the pinacol rearrangement, e.g. by heating with sulfuric acid: [2]

800px-Pinacol rearragement.png

Pinacol can be used with borane and boron trichloride to produce useful synthetic intermediates such as pinacolborane, bis(pinacolato)diboron, [3] and pinacolchloroborane.

See also

Related Research Articles

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A pinacol coupling reaction is an organic reaction in which a carbon–carbon bond is formed between the carbonyl groups of an aldehyde or a ketone in presence of an electron donor in a free radical process. The reaction product is a vicinal diol. The reaction is named after pinacol, which is the product of this reaction when done with acetone as reagent. The reaction is usually a homocoupling but intramolecular cross-coupling reactions are also possible. Pinacol was discovered by Wilhelm Rudolph Fittig in 1859.

<span class="mw-page-title-main">Wilhelm Rudolph Fittig</span> German chemist (1835–1910)

Wilhelm Rudolph Fittig was a German chemist. He discovered the pinacol coupling reaction, mesitylene, diacetyl and biphenyl. Fittig studied the action of sodium on ketones and hydrocarbons. He discovered the Fittig reaction or Wurtz–Fittig reaction for the synthesis of alkylbenzenes, he proposed a diketone structure for benzoquinone and isolated phenanthrene from coal tar. He discovered and synthesized the first lactones and investigated structures of piperine, naphthalene, and fluorene.

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Pinacolone (3,3-dimethyl-2-butanone) is an important ketone in organic chemistry. It is a colorless liquid with a slight peppermint or camphor odor. It is a precursor to triazolylpinacolone in the synthesis of the fungicide triadimefon and in synthesis of the herbicide metribuzin. The molecule is an unsymmetrical ketone. The α-methyl group can participate in condensation reactions. The carbonyl group can undergo the usual reactions. It is a Schedule 3 compound under the Chemical Weapons Convention 1993, due to being related to pinacolyl alcohol, which is used in the production of soman. It is also a controlled export in Australia Group member states.

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<span class="mw-page-title-main">Bis(pinacolato)diboron</span> Chemical compound

Bis(pinacolato)diboron is a covalent compound containing two boron atoms and two pinacolato ligands. It has the formula [(CH3)4C2O2B]2; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as B2pin2. It is a colourless solid that is soluble in organic solvents. It is a commercially available reagent for making pinacol boronic esters for organic synthesis. Unlike some other diboron compounds, B2pin2 is not moisture-sensitive and can be handled in air.

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References

  1. Roger Adams and E. W. Adams. "Pinacol Hydrate". Organic Syntheses ; Collected Volumes, vol. 1, p. 459.
  2. G. A. Hill and E. W. Flosdorf (1941). "Pinacolone". Organic Syntheses ; Collected Volumes, vol. 1, p. 462.
  3. Tatsuo Ishiyama; Miki Murata; Taka-aki Ahiko; Norio Miyaura (2004). "Bis(pinacolato)diboron". Organic Syntheses ; Collected Volumes, vol. 10, p. 115.