Photosensitized cis/trans isomerization of 1-(1-propenyl)cycloalkenes

Journal Article · Fri Sep 29 00:00:00 EDT 1989 · Journal of Organic Chemistry; (USA)

DOI:https://doi.org/10.1021/jo00281a032· OSTI ID:6971371

Inman, W D; Sanchez, K A.J.; Chaidez, M A; Paulson, D R ^[1]

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1. California State Univ., Los Angeles (USA)

The photosensitized cis/trans isomerization of a series of 1-(1-propenyl)cycloalkenes is reported. A plot of the photostationary state trans/cis ratio vs the sensitizer triplet energy for 1-(1-propenyl)cyclopentene shows a constant trans/cis ratio of {approx} 1.0 with high-energy sensitizers (E{sub T} > 61 kcal/mol). The plot shows one maxima at E{sub T} {approx} 55 kcal/mol with low-energy sensitizers (E{sub T} < 61 kcal/mol). This type of plot is very similar to those obtained with acyclic dienes such as piperylene. The 1-(1-propenyl)cyclohexene system shows a similar plot with high-energy sensitizers, but with low-energy sensitizers this system shows two maxima occurring at 56 and 47 kcal/mol, respectively. This double-maxima plot is rationalized by an unusually low trans/cis decay ratio for the s-cis relaxed triplet state of the 1-(1-propenyl)cyclohexene system. This double maxima is not observed in other diene systems due to a high trans/cis decay ratio for their s-cis relaxed triplet states. The photosensitized cis/trans isomerization of 2-ethylidene-10-methyl-1(9)-octalin was also studied as a model for a conformationally locked s-trans system. The 1-(1-propenyl)cycloheptene system undergoes photosensitized cis/trans isomerization, but photostationary cis/trans isomerization data could not be obtained due to a very efficient photosensitized dimerization of this diene system.

• OSTI ID: 6971371
• Journal Information: Journal of Organic Chemistry; (USA), Journal Name: Journal of Organic Chemistry; (USA) Vol. 54:20; ISSN 0022-3263; ISSN JOCEA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
400500 -- Photochemistry
ALKENES
CHEMICAL REACTIONS
CYCLOALKENES
DATA
DATA ANALYSIS
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
ISOMERIZATION
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOSENSITIVITY
SENSITIVITY