This was one of two molecules for this week.
November 19, 2018
Mmmm . . . we smell so good!
What molecules are we?
Image of 2-Hexylthiophene

Thanksgiving traditionally means turkey; and turkey means the aromas that waft throughout the house while it’s roasting. But what’s responsible for these delicious smells?

Answer: the Maillard reaction. Discovered by French chemist Louis-Camille Maillard in 1912, the “reaction” is actually a complex series of steps that begins with the interaction between carbonyl groups of open-chain sugars and amine groups of amino acids to form N-aldosylamines. Eventually, depending on the food being heated, the sequence ends with the creation of multiple chemical entities, including many heterocyclic compounds.

These reactions occur when foodstuffs are heated to 140–165 ºC. In addition to the aromas they produce, they are responsible for browning baked, grilled, or roasted foods such as breads, vegetables, and meats. Browning is accelerated in an alkaline environment.

All of which brings us back to turkey. As with other roasted meats, the Maillard reaction produces numerous compounds. Two that have been reported in the literature are 2-pentylpyridine and 2-hexylthiophene, shown here. (No systematic study of all of the Maillard products from turkey appears to have been conducted.)

So, when your host serves you delicious roasted turkey with all the fixings, please compliment her or him on an excellent helping of 2-pentylpyridine and 2-hexylthiophene.

2-Pentylpyridine hazard information

GHS classification*: flammable liquids, category 4
H227—Combustible liquid
GHS classification: skin irritation, category 2
H315—Causes skin irritation Chemical Safety Warning
GHS classification: serious eye irritation, category 2A
H319—Causes serious eye irritationChemical Safety Warning
GHS classification: specific target organ toxicity, single exposure; respiratory tract irritation, category 3
H335—May cause respiratory irritationChemical Safety Warning

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

2-Hexylthiophene hazard information

GHS classification: acute toxicity, oral, category 4
H302—Harmful if swallowedChemical Safety Warning
GHS classification: serious eye irritation, category 2A
H319—Causes serious eye irritationChemical Safety Warning
GHS classification: hazardous to the aquatic environment, long-term hazard, category 4
H413—May cause long-lasting harmful effects to aquatic life

2-Pentylpyridine fast facts

CAS Reg. No.2294-76-0
Empirical formulaC10H15N
Molar mass149.23
AppearanceColorless to yellow liquid
Boiing point206–210 ºC
Water solubility≈1 g/L (est.)

2-Hexylthiophene fast facts

CAS Reg. No.18794-77-9
Empirical formulaC10H16S
Molar mass168.30
AppearanceColorless to pale yellow liquid
Boiling point228–230 ºC
Water solubility<1 g/L (est.)
Chemical Abstract Service - a division of ACS

Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.

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