Quinones are normally used to quench reactions.
But I am working on reactions of quinone itself, and I would like to quench them. Do you have any suggestions on this? Just a situation in my case, the quinone compound is not stable under acidic conditions at low temperature (-20 oC).
Quenching of quinones should be possible with formation of adducts or addition compounds, for example with aliphatic and aromatic phosphines. You may visit some of our papers on the subject.
Mirza Arshad Ali Beg
Former Director General PCSIR Karachi
Presumably you want to preserve your quinone whilst quenching the reaction conditions?
Herewith are abstracts of a few papers that we published way back in 1969:
Spectroscopic studies of organophosphorus compounds—III : The constitution of the phosphine-quinone adducts, M. Arshad A. Beg, & M.S. Siddiqui Tetrahedron
Volume 22, Issue 7, 1966, Pages 2203–2211
Pakistan J. Sci. Ind. Res., 12, 334-336 (1970) SPECTROSCOPIC STUDIES OF ORGANOPHOSPHORUS COMPOUNDS Part V.-Ultraviolet Spectra of Phosphine-j-Benzquinone Adducts M. ARSHAD A. BEG and M.S. SIDDIQUI P.C.S.I.H. Laboratories, Karachi 32 (Received February 17, 1969)
The UV spectra of phosphine-p-benzoquinone adducts have been studied under acid and basic conditions. The position of the bands is susceptible to changes in pH. In the acid medium there is a decrease in intensity of the n+x transition, as in ionized carboxyls while in the basic medium, there is a red shift with an enhancement in intensity, which is characteristic of phenols. In the phosphonium dithioformates also similar variations are noted. These observations suggest that the betairie structure is favoured in the acid medium while the phosphinemethylene structure is dominant in the basic medium.
Pakistan J. Sci. Ind. Res., 12, 337-338 (1970) THIOPHOSPHORYL ADDUCTS OF NITROGEN BASES M. ARSHAD A. BEG and M.S. SIDDIQUI P.C.S.I.R. Laboratories, Karachi 32 (Received March 10, 1969) Thiophosphoryl and phenylthiophosphoryl chloride have been shown to form adducts with ethylenediamine and dipyridyl in variable ratios. Similar adducts of pyridine could not be purified. The stoichiometry seems to depend on the number of chlorines attached to phosphorus. In the case of dipyridyl complexes, thiophosphoryl chloride forms the adducts in the ratio 2:5 while phenylthiophosphoryl chloride forms a 1 :I adduct. With ethylenediamine, on the other hand, the ratio with thiophosphoryl chloride is 4:15 and with phenylthiophosphoryl chloride it is 2:5 The adducts have been formulated as ionic substances.
Pakisran J. Sci. Ind. Res., 12, 19-12 (1969) PHOSPHINE ADDUCTS OF POLYNITROARYLS M. ARSHAD A. BEG and M.S. SIDDIQUI P. C. S. I. R. Laboratories, Karachi 32 (Received July 9, 1968) Phosphines form addition compounds with polynitro aromatic compounds like picric acid, 1,3,5-trinitrobenzene and 2,4-dinitrophenol. Picrates of the alkyl phosphines are obtained in good yield from stoichiometric amounts of picric acid and phosphines, viz. trimethylphosphine, tributylphosphine, phenyldimethylphosphine, triphenylphosphine and tri-p-tolylphospine. The alkylphosphines react instantaneously at room temperature with the deposition of the intensely coloured compounds. Yellow solids which gradually transform into the deep coloured compounds are also obtained when the reaction is carried out at lower temperatures. With the arylphosphines an intermediate yellow solid is not obtained, the reaction is very slow and it is only on long refluxing that dark solid is obtained. Only the alkylphosphines react with the other nitroaryls. From the intensity of the colour and their reactions with acid and alkali the compounds are suggested to be zwitterionic in nature.
There is also the Thesis on the subject on the HEC Website.
You may suceed in partial quenching or selective quenching with alkyl - aryl substituted phosphines.
Dr. Mirza Arshad Ali beg
Former Director General PCSIR, Karachi
OK, so what you are really after here is a way of quenching the amines without destroying your acid sensitive quinones. You could try adding a lewis acid to bind the amines, something like B(OMe)3 or a competitive electrophile that won't react with your product.
Reduction to the dihydroquinone might also halt addition for the purposes of analysis. Although you would have regenerate the quinone after separation.
Yang's quinones react with amines to form adducts. This is a spontaneous reaction which he needs to stop at a stage when he can analyze the product.
The products that we get on reaction of quinones with bases are betaines with zwitterionic character.The betaine will be more basic with the use of weakly acidic quinones and vice versa. So if you want to quench your quinones Mr. Yang you will have vary the basicity of the amines or may switch over to substituted phosphines or arsines. In our experiments we find it difficult to obtain a single compound and the products are usually mixed up.
Mirza Arshad Ali Beg
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