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2,2,4-Trimethyl-1,2-dihydroquinoline

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2,2,4-Trimethyl-1,2-dihydroquinoline
Structure of 2,2,4-Trimethyl-1,2-dihydroquinoline monomer
Monomer
Names
Preferred IUPAC name 2,2,4-trimethyl-1,2-dihydroquinoline
Other names 1,2-Dihydro-2,2,4-trimethylquinoline
Identifiers
CAS Number
3D model (JSmol)
EC Number
  • 500-051-3
InChI
  • InChI=1S/C12H15N/c1-9-8-12(2,3)13-11-7-5-4-6-10(9)11/h4-8,13H,1-3H3Key: ZNRLMGFXSPUZNR-UHFFFAOYSA-N
SMILES
  • CC=1C=2C(NC(C)(C)C1)=CC=CC2
Properties
Chemical formula C12H15N
Molar mass 173.259 g·mol
Appearance Solid
Density 1.042 at 20°C
Melting point 48 °C (118 °F; 321 K)
Solubility in water 1 mg/L
Hazards
GHS labelling:
Signal word Warning
Hazard statements H412
Precautionary statements P273
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references
Chemical compound

2,2,4-Trimethyl-1,2-dihydroquinoline (usually abbreviated TMQ, known historically as Acetone-anil) is an aminic antioxidant commonly used as a stabiliser in rubbers and some plastics.

Synthesis

TMQ is produced by a poly-condensation reaction between aniline and acetone.

Structure

The most common of several possible TMQ dimers. CAS 18121-94-3

The structure of TMQ is often represented by the monomer; however, the commercial material is typically a complex mixture of oligomers. Dimers, trimers, and tetramers are common, but high molecular weight versions are also available. ECHA includes nearly a dozen compounds in the registration for TMQ. Differences in composition between suppliers can affect performance, resulting a complex market.

Applications

TMQ is primarily used in rubber. It is a good antioxidant, but it gives low protection against flex cracking (fatigue) and is not effective as an antiozonant. In tire formulations it is often paired with 6PPD. The high molecular weight of TMQ oligomers makes them non-volatile and therefore more effective as long term heat-protection agents. It also makes them less likely to leach out of the polymer. A TMQ is relatively inert towards the cross-linking peroxides used to produce EPDM, or PEX and it therefore also sees use in these polymers.

See also

  • Ethoxyquin - a structurally related antioxidant used as a preservative in foods

References

  1. "2,4-DIMETHYLQUINOLINE". Organic Syntheses. 28: 49. 1948. doi:10.15227/orgsyn.028.0049.
  2. "Registration Dossier - ECHA". echa.europa.eu. Retrieved 8 January 2025.
  3. Wiley-VCH, ed. (2003-03-11). "Rubber, 9. Chemicals and Additives". Ullmann's Encyclopedia of Industrial Chemistry (1 ed.). Wiley. doi:10.1002/14356007.a23_365.pub3. ISBN 978-3-527-30385-4.
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