Guaiazulene

Chembox new
Name = Guaiazulene
ImageFile = Guaiazulene.png ImageName = Guaiazulene
IUPACName = 1,4-dimethyl-7-isopropylazulene
Section1 = Chembox Identifiers
CASNo = 489-84-9
SMILES = SMILES|S=CC2=C1C(C=C2) =C(C)C=C C(C(C)C)=C1
Section2 = Chembox Properties
Formula = C₁₅H_{18
MolarMass = 198.31 g/mol
Density = 0.976 g/cm³
MeltingPt = 31-33 °C
BoilingPt = 153 °C (7 mm Hg)}

Guaiazulene, also azulon or 1,4-dimethyl-7-isopropylazulene, is a dark blue crystalline hydrocarbon and a derivative of azulene. Specifically, it is a bicyclic sesquiterpene that occurs naturally as a constituent of some essential oils, mainly oil of guaiac and chamomile oil, which also serve as its commercial sources. Various soft corals also contain guaiazulene as a principal pigment.

Guaiazulene is an FDA-approved cosmetic color additive. It is also a common component of cosmetics like shampoos or skin care products with other skin soothing compounds such as allantoin.

Guaiazulene has applications as an anti-ulcer drug, and can be also used as a volatile dye with a known evaporation rate to indicate end of use of various products (such as insecticide strips.)

Guaiazulene's low melting point can cause it to be difficult to use in chemical synthesis. Much like it's similarly colored cousin azulene, guaiazulene has an uneven distribution of electrons between the seven and five membered rings. In order to obey the Huckel rule, the seven membered ring attempts to transfer an electron to the five membered ring. Although somewhat incomplete, this electron transfer creates a dipole moment of ~1 debye; another unusual property for a hydrocarbon.

The five membered ring then acquires a partial negative charge, making it a prime target for electrophillic aromatic substitution.

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