Photohydration reaction of 1-Aryl-5,5-dimethyl-1,3-hexadiynes = 1-아릴-5,5-디메틸-1,3-헥사디인의 광수화반응

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The photohydration reaction of 1-phenyl-5,5-dimethyl-1,3-hexadiyne (PDHD) in 10% aq. sulfuric acid gives two acetylenyl ketones and one allenyl ketone compound. The effect of 9-fluorenone-1-carboxylic acid on photohydration of PDHD shows the curved plot in Stern-Volmer plot indicating that the three photohydration products are formed via both singlet and triplet excited states. The plot of quantum yields versus medium acidity show a sigmoidal curve suggesting that the acetylenyl ketone compounds are produced by the mechanism in which the protonation step is the rate-limiting step. On the other hand, the allenyl ketone compound shows the maximum efficiency at $H_0=-0.7$ as medium acidity is increased. The results suggest the synchronous addition of water with protonation. Irradiation of 1-(p-nitrophenyl)-5,5-dimethyl-1,3-hexadiyne (p-NDHD) in aqueous 10% sulfuric acid yields two conjugated allenyl ketones and two β-dicarbonyl compounds. It is found from the kinetic studies that the p-NDHD is initially converted into two allenyl ketones and two β-dicarbonyl compounds are produced as secondary photoproducts. Treatment of the primary photoproducts with 10 % sulfuric acid yields the secondary products very rapidly, suggesting that the secondary hydration is a thermal process. The fast thermal hydration of allenyl ketones is probably due to the fast 1,4-addition of water as in α,β-unsaturated ketones. The oxygen effects on the photohydration of p-NDHD and linear Stern-Volmer plot on 9-fluorenone-1-carboxylic acid quenching strongly support that the triplet excited states of p-NDHD are involved in the photohydration mechanism. The maximum efficiency at $H_0=-1.0$ is observed in the photohydration quantum yield measurements as a function of acidity for p-NDHD. The suggested mechanism involves the nucleophilic attack of water, synchronous with proton transfer. Irradiation of 1-(m-nitrophenyl) -5,5-dimethyl-1,3-hexadiyne (m-NDHD) in 5% sulfuric acid gives two hydration p...
Advisors
Shim, Sang-Chul심상철
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
1996
Identifier
105350/325007 / 000935175
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 1996.2, [ vi, 75 p. ]

Keywords

Photohydration Reaction; Photochemistry; Hexadiynes; 헥사디인; 광수화반응; 광화학

URI
http://hdl.handle.net/10203/31430
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=105350&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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