3,5-Dimethylpyrazole

3,5-Dimethylpyrazole
Names
	Preferred IUPAC name 3,5-Dimethyl-1H-pyrazole
Identifiers
CAS Number	67-51-6;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL1828957;
ChemSpider	5975;
ECHA InfoCard	100.000.597
EC Number	200-657-5;
PubChem CID	6210;
UNII	H21N865K9J;
CompTox Dashboard (EPA)	DTXSID5058777 ;
	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−1
Appearance	white solid
Density	1.027 g/cm3
Melting point	107.5 °C (225.5 °F; 380.6 K)
Boiling point	218 °C (424 °F; 491 K)
Hazards
	GHS labelling:
Pictograms
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 [77 °F], 100 kPa). Infobox references

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 C_2v 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.^[1]^[2]

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

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

It has found use as a blocking agent for isocyanates.^[4]

References

^ 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 {[tris(pyrazolyl)methane]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)00290-4.1–2&rft.pages=120-128&rft.date=2000&rft_id=info:doi/10.1016/S0022-328X(00)00290-4&rft.aulast=Reger&rft.aufirst=Daniel L.&rft.au=Grattan, T.Christian&rft.au=Brown, Kenneth J.&rft.au=Little, Christine A.&rft.au=Lamba, Jaydeep J.S.&rft.au=Rheingold, Arnold L.&rft.au=Sommer, Roger D.&rfr_id=info:sid/en.wikipedia.org:3,5-Dimethylpyrazole" class="Z3988">
^ 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/ic00209a003.2334-2337&rft.date=1985&rft_id=info:doi/10.1021/ic00209a003&rft.aulast=Schenck&rft.aufirst=Terry G.&rft.au=Downes, J. M.&rft.au=Milne, C. R. C.&rft.au=MacKenzie, Peter B.&rft.au=Boucher, Terry G.&rft.au=Whelan, John&rft.au=Bosnich, B.&rfr_id=info:sid/en.wikipedia.org:3,5-Dimethylpyrazole" class="Z3988">
^ Johnson, William S.; Highet, Robert J. (1951). "3,5-Dimethylpyrazole". Organic Syntheses. 31: 43. doi:10.15227/orgsyn.031.0043.
^ "Blocked Isocyanates" (PDF). Lanxess. June 2020. Archived (PDF) from the original on 2020-09-27.

[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 {[tris(pyrazolyl)methane]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)00290-4.1–2&rft.pages=120-128&rft.date=2000&rft_id=info:doi/10.1016/S0022-328X(00)00290-4&rft.aulast=Reger&rft.aufirst=Daniel L.&rft.au=Grattan, T.Christian&rft.au=Brown, Kenneth J.&rft.au=Little, Christine A.&rft.au=Lamba, Jaydeep J.S.&rft.au=Rheingold, Arnold L.&rft.au=Sommer, Roger D.&rfr_id=info:sid/en.wikipedia.org:3,5-Dimethylpyrazole" class="Z3988">

[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/ic00209a003.2334-2337&rft.date=1985&rft_id=info:doi/10.1021/ic00209a003&rft.aulast=Schenck&rft.aufirst=Terry G.&rft.au=Downes, J. M.&rft.au=Milne, C. R. C.&rft.au=MacKenzie, Peter B.&rft.au=Boucher, Terry G.&rft.au=Whelan, John&rft.au=Bosnich, B.&rfr_id=info:sid/en.wikipedia.org:3,5-Dimethylpyrazole" class="Z3988">

[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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