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

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

Monomer
Names
Preferred IUPAC name 2,2,4-Trimethyl-1,2-dihydroquinoline
Other names 1,2-Dihydro-2,2,4-trimethylquinoline TMQ Antioxidant
Identifiers
CAS Number	26780-96-1
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL294154
ChemSpider	8633
ECHA InfoCard	100.005.172
EC Number	500-051-3
PubChem CID	8981
UNII	0553M374Q3
CompTox Dashboard (EPA)	DTXSID0025070
InChI InChI=1S/C12H15N/c1-9-8-12(2,3)13-11-7-5-4-6-10(9)11/h4-8,13H,1-3H3 Key: ZNRLMGFXSPUZNR-UHFFFAOYSA-N
SMILES CC=1C=2C(NC(C)(C)C1)=CC=CC2
Properties
Chemical formula	C12H15N
Molar mass	173.259 g·mol−1
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:
Pictograms
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 [77 °F], 100 kPa). Infobox references

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. ^[1]

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. ^[2] 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. ^[3] 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. TMQ is relatively inert towards the cross-linking peroxides used to produce EPDM, or PEX and it therefore also sees use in these polymers. ^[4]

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.
4. Ferradino, Anthony G. (1 July 2003). "Antioxidant Selection for Peroxide Cure Elastomer Applications". Rubber Chemistry and Technology. 76 (3): 694–718. doi:10.5254/1.3547763.