2,6-Lutidine

Chemical properties

Colorless to yellow liquid

Chemical properties

2,6-Dimethylpyridine has a powerful and diffusive minty-tarry odor. It has also been described to have the odor of pyridine and peppermint

Occurrence

Reported found in bread, tea, peppermint oil, cheeses, chicken, beef, pork, beer, sherry, whiskies, cocoa, coffee, tea, oatmeal, rice bran, buckwheat and malt.

The Uses of 2,6-Lutidine

2,6-Lutidine is used as a solvent in organic synthesis and as a sterically hindered mild base. It is also used as a vulcanization accelerator for dyes, resins and rubber. It also acts as a food additive.

The Uses of 2,6-Lutidine

A mixture of the SM (2.0 g, 10.0 mmol), 2,6-lutidine (2.13 g, 19.9 mmol), TBSOTf (3.1 g, 14.9 mmol), and DCM (30 mL) was stirred at RT for 2 h. The reaction mixture was quenched with H2O (20 mL), then extracted with DCM. The org layer was dried (Na2SO4) and concentrated. The crude residue was purified by silica gel chromatography (20:1 petroleum ether/EtOAc) to provide the product as a colorless oil.

The Uses of 2,6-Lutidine

Isolated from the basic fraction of coal tar. A semi-volatile compound in tobacco.

Definition

ChEBI: A member of the class of methylpyridines that is pyridine carrying methyl substituents at positions 2 and 6.

Taste threshold values

Taste characteristics at 20 ppm: nutty, coffee, cocoa, musty, bready and meaty

Synthesis Reference(s)

Organic Syntheses, Coll. Vol. 2, p. 214, 1943
Tetrahedron Letters, 17, p. 383, 1976 DOI: 10.1016/S0040-4039(00)93738-9

General Description

A colorless liquid with a peppermint odor. Flash point 92°F. Less dense than water. Vapors heavier than air. Produces toxic oxides of nitrogen during combustion. Used to make other chemicals.

Air & Water Reactions

Highly flammable. Soluble in water.

Reactivity Profile

2,6-Lutidine neutralizes acids in exothermic reactions to form salts plus water. May be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen may be generated in combination with strong reducing agents, such as hydrides.

Health Hazard

Inhalation or contact with material may irritate or burn skin and eyes. Fire may produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.

Flammability and Explosibility

Flammable

Synthesis

Synthesis from ethyl acetoacetate, formaldehyde and ammonia; isolated from basic fraction of coal tar

Purification Methods

Likely contaminants include 3-and 4-picoline (similar boiling points). However, they are removed by using BF3, with which they react preferentially, by adding 4mL of BF3 to 100mL of dry fractionally distilled 2,6-lutidine and redistilling. Distillation of commercial material from AlCl3 (14g per 100mL) can also be used to remove picolines (and water). Alternatively, lutidine (100mL) can be refluxed with ethyl benzenesulfonate (20g) or ethyl p-toluenesulfonate (20g) for 1hour, then the upper layer is cooled, separated and distilled. The distillate is refluxed with BaO or CaH2, then fractionally distilled through a glass helices-packed column. 2,6-Lutidine can be dried with KOH or sodium or by refluxing with (and distilling from) BaO, prior to distillation. For purification via its picrate, 2,6-lutidine, dissolved in absolute EtOH, is treated with an excess of warm ethanolic picric acid. The precipitate is filtered off, recrystallised from acetone (to give m 163-164.5o (166-167o), and partitioned between ammonia and CHCl3/diethyl ether. The organic layer, after washing with dilute aqueous KOH, is dried with Na2SO4 and fractionally distilled. [Warnhoff J Org Chem 27 4587 1962.] Alternatively, 2,6-lutidine can be purified via its urea complex, as described under 2,3-lutidine. Other purification procedures include azeotropic distillation with phenol [Coulson et al. J Appl Chem (London) 2 71 1952], fractional crystallisation by partial freezing, and vapour-phase chromatography using a 180-cm column of polyethylene glycol-400 (Shell, 5%) on Embacel (May and Baker) at 100o, with argon as carrier gas [Bamford & Block J Chem Soc 4989 1961]. The hydrochloride has m 235-237o, 239o (from EtOH). [Beilstein 20 II 160, 20 III/IV 2776, 20/6 V 32.]