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3,5-Dimethylpyrazole

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3,5-Dimethylpyrazole
Names
Preferred IUPAC name 3,5-Dimethyl-1H-pyrazole
Identifiers
CAS Number
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.000.597 Edit this at Wikidata
EC Number
  • 200-657-5
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C5H8N2/c1-4-3-5(2)7-6-4/h3H,1-2H3,(H,6,7)Key: SDXAWLJRERMRKF-UHFFFAOYSA-N
SMILES
  • CC1=CC(=NN1)C
Properties
Chemical formula C5H8N2
Molar mass 96.133 g·mol
Appearance white solid
Density 1.027 g/cm
Melting point 107.5 °C (225.5 °F; 380.6 K)
Boiling point 218 °C (424 °F; 491 K)
Hazards
GHS labelling:
Pictograms GHS07: Exclamation markGHS08: Health hazard
Signal word Warning
Hazard statements H302, H315, H319, H335, H361, H373
Precautionary statements P201, P202, P260, P261, P264, P270, P271, P280, P281, P301+P312, P302+P352, P304+P340, P305+P351+P338, P308+P313, P312, P314, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references
Chemical compound

3,5-Dimethylpyrazole is an organic compound with the formula (CH3C)2CHN2H. It is one of several isomeric derivatives of pyrazole that contain two methyl substituents. The compound is unsymmetrical but the corresponding conjugate acid (pyrazolium) and conjugate base (pyrazolide) have C2v symmetry. It is a white solid that dissolves well in polar organic solvents.

It is a precursor to a variety of ligands that are widely studied in coordination chemistry including trispyrazolylborate, a trispyrazolylmethane, and a pyrazolyldiphosphine.

Condensation of acetylacetone and hydrazine gives 3,5-dimethylpyrazole:

CH3C(O)CH2C(O)CH3   +   N2H4   →   (CH3C)2CHN2H   +   2 H2O

It has found use as a blocking agent for isocyanates.

References

  1. Reger, Daniel L.; Grattan, T.Christian; Brown, Kenneth J.; Little, Christine A.; Lamba, Jaydeep J.S.; Rheingold, Arnold L.; Sommer, Roger D. (2000). "Syntheses of tris(pyrazolyl)methane ligands and {Mn(CO)3}SO3CF3 complexes: Comparison of ligand donor properties". Journal of Organometallic Chemistry. 607 (1–2): 120–128. doi:10.1016/S0022-328X(00)00290-4.
  2. Schenck, Terry G.; Downes, J. M.; Milne, C. R. C.; MacKenzie, Peter B.; Boucher, Terry G.; Whelan, John; Bosnich, B. (1985). "Bimetallic reactivity. Synthesis of bimetallic complexes containing a bis(phosphino)pyrazole ligand". Inorganic Chemistry. 24 (15): 2334–2337. doi:10.1021/ic00209a003.
  3. Johnson, William S.; Highet, Robert J. (1951). "3,5-Dimethylpyrazole". Organic Syntheses. 31: 43. doi:10.15227/orgsyn.031.0043.
  4. "Blocked Isocyanates" (PDF). Lanxess. June 2020. Archived (PDF) from the original on 2020-09-27.
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