Seven-carbon ring compound
Tropolone, also known as tohenone and 2-hydroxygenone, is a kind of seven-carbon ring compound, which is weakly acidic and has the properties of aromatic compounds, double bond and weak ketone. There are more than ten kinds of compounds known in nature containing seven-carbon rings:
- Hinokitiol, as a red iron complex, is found in cypress wood in Taiwan.
- Alpha- and gamma-thujapricin (β-body is the same as hinokitiol) are found in cypress and coniferous plants. It acts as an antibacterial agent to the wood for anticorrosion
- α- body and β-body also exist in the cypress essential oil. Stipitatic acid (6- hydroxyaryl heptanone-4-carboxylic acid) is the metabolite of penicillium, and has an antibacterial effect.
- Purpurogallin, as glycoside, is found in the galls of mistletoe plants and can be used as a phenol oxidase test.
- As nootkatin of the nootka heartwood and subalkaloids of colchicine and the like of colchicum used as inhibitor.
According to the properties of the compounds above, the scientists speculate that tocophenone plays an important role in the metabolic process of living components. It wss Japanese scientists Tetsuo Nozoe who first paid attention to tropolone in 1936 when he was researching hinokitiol, while the work in Europe and the United States started from the structure of stipitatic acid and colchicine, going further after 1950.
Uses
Known as pyrrole pesticide, acaricide with new structure, it has been proved to have good biological control effect on boring, piercing-sucking and chewing insects and mites, better than cypermethrin and cypermethrin. Also its acaricidal activity is stronger than dicofol and tricyclic tin. This agent is characterized with the following: broad-spectrum pesticide and acaricide; both stomach poisoning and contact toxicity; no mutual resistance with other pesticides; moderate residual activity in crops; selective and systemic activity in nutrient solution absorbed by root system; moderate oral toxicity and lower dermal toxicity to mammalian life; low effective spray rate (100g active ingredient / hm2). Its significant insecticidal, acaricidal activity and unique chemical structure has received widespread attention and attention.
Toxicity
The acute oral toxicity LD50 in rats was 459 mg / kg (female) , 223 mg / kg (male) and (662 mg / kg, rat). The acute dermal toxicity LD(50) in rabbit was no less than 2000mg/kg. There was mild irritation to the eye of rabbits. LC50 in Japanese carp is 0.5mg / L (48h) . An improved test and hamster ovary test, done by Ames, showed no mutations had been caused. Japanese carp LC50 is 0.5mg / L (48h)
Chemical Properties
White to light yellow crystalline
Uses
Tropolone is a sensitive reagent for reducing sugars. A non-benzenoid aromatic compound, Reagent for the preparation of fused heterocycles and complexes of Ga(III) and In(III).
Uses
Reagent for the preparation of fused heterocycles1 and complexes of Ga(III) and In(III).2
Used as medicine and dye intermediates.
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
Not classified
Synthesis
To a mixture of sodium hydroxide (33 g) with glacial acetic acid (270 ml) was added dropwise via funnel 7,7-dichlorobicyclo[3,2,0]hepta-2-ene-6-ketone (33.5 g) under nitrogen, and the mixture was heated to reflux for 8 hours. After PH was adjusted to 1 with hydrochloric acid (50 ml), the mixture was filtered and extracted with benzene (3 × 90ml). The combined extracts were concentrated in vacuo to give brownish black oil.Fraction of reduced pressure distillation at 100 °C/67 Pa was collected to give gross product as a pale yellow solid. Recrystallization from mixture of dichloromethane and pentane (1/4, V/V) gave analytically pure product Tropolone(17.8 g,77%) as a white needle crystal, m.p. 50~51 °C.
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.
