3,5-dimethylpyrazole
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| General | ||||||||||||||||
| Surname | 3,5-dimethylpyrazole | |||||||||||||||
| Molecular formula | C 5 H 8 N 2 | |||||||||||||||
| Brief description |
white to yellow solid with a pleasant odor |
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| properties | ||||||||||||||||
| Molar mass | 96.13 g mol −1 | |||||||||||||||
| Physical state |
firmly |
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| density |
0.72 g cm −3 ( bulk density ) |
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| Melting point |
105-108 ° C |
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| boiling point |
218 ° C |
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| solubility |
slightly soluble in water (31 g l −1 at 20 ° C) |
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| safety instructions | ||||||||||||||||
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||
3,5-Dimethylpyrazole is a chemical compound from the group of pyrazoles . It is used as a synthesis base and as a blocking agent for isocyanates in polyurethane coatings. Only N - tert -butyl- N -benzylamine (BEBA) and 3,5-dimethylpyrazole have hardly any tendency to thermal yellowing due to baking.
Extraction and presentation
3,5-dimethylpyrazole can be prepared by condensation of acetylacetone and hydrazine (z. B. hydrazine sulphate are obtained in aqueous alkaline solution).
safety instructions
In 2015, 3,5-dimethylpyrazole was included in the EU's ongoing action plan ( CoRAP ) in accordance with Regulation (EC) No. 1907/2006 (REACH) as part of substance evaluation . The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. The reasons for the intake of 3,5-dimethylpyrazole were concerns about the high risk characterization ratio (RCR) and the suspected dangers of reproductive properties. The re-evaluation should be carried out by Spain from 2020 .
Individual evidence
- ↑ a b c Wacker: Heterocyclics - 3,5-Dimethylpyrazole , accessed on January 27, 2019.
- ↑ a b Data sheet 3,5-Dimethylpyrazole from Sigma-Aldrich , accessed on May 21, 2017 ( PDF ).
- ↑ a b Entry on 3,5-dimethylpyrazole in the GESTIS substance database of the IFA , accessed on January 9, 2019(JavaScript required) .
- ^ Ulrich Meier-Westhues: Polyurethanes: Paints, adhesives and sealants . Vincentz, 2007, p. 41 ( limited preview in Google Book search).
- ↑ Richard H. Wiley, Peter E. Hexner: 3,5-Dimethylpyrazol In: Organic Syntheses . 31, 1951, p. 43, doi : 10.15227 / orgsyn.031.0043 ; Coll. Vol. 4, 1963, p. 351 ( PDF ).
- ↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): 3,5-dimethylpyrazole , accessed on March 26, 2019.