Chemical Properties
White to light yellow crystalline
Definition
ChEBI: Tropolone is a cyclic ketone that is cyclohepta-2,4,6-trien-1-one substituted by a hydroxy group at position 2. It is a toxin produced by the agricultural pathogen Burkholderia plantarii. It has a role as a bacterial metabolite, a toxin and a fungicide. It is a cyclic ketone, an enol and an alpha-hydroxy ketone. It derives from a hydride of a cyclohepta-1,3,5-triene.
Flammability and Explosibility
Notclassified(100%)
Synthesis
Sodium hydroxide with glacial acetic acid was added dropwise under nitrogen,and the mixture was heated to reflux. PH was adjusted，the mixture was filtered and extracted with benzene .The combined extracts were concentrated to give brownish black oil.Fraction of reduced pressure distillation was collected to give gross product as a pale yellow solid. Recrystallization from mixture of dichloromethane and pentane gave analytically pure product as a white needle crystal.
Purification Methods
Crystallise tropolone from hexane or pet ether and sublime it at 40o/4mm. Also distil it at high vacuum. [Beilstein 8 IV 159.]
structure and hydrogen bonding
The tropolone has a simple structure consisting of a seven-membered carbon ring. The pi electrons present in the ring are delocalised. A ketone grouped to the first carbon, and an hydroxyl group attached to the second carbon. Tropolone, C7H6O2, crystallizes in space group P21/c, with a = 7.135, b = 12.178, c = 7.122Å, β = 99.63 ° and Z = 4. The molecule is essentially planar and exhibits slight bond alternation in the seven-membered ring. The hydroxyl group makes a bifurcated hydrogen bond with carbonyl oxygen atoms, of which one branch is intramolecular and the other intermolecular. The latter intermolecular branches form a hydrogen-bonded dimer. These characteristic hydrogen bonds seem to play a role in increasing the contribution from the dipolar ionic forms to the ground state of the tropolone molecule.
