Category Main components Aromatic hydrocarbons Ethylbenzene, 1,3-dimethyl benzene, 1-methylene lH-indene, butylated hydroxy toluene, 1-methylnaphthalene, 2-methylnaphthalene Alkanes Undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, 2,6,10-trimethyl dodecyl, 4-(prop-2 loxypropangl)octane, 2,6-dimethyl decane Alkenes 2-Propenylidene cyclobutene
, cedrene, Seychelles alkene Aldehydes and ketones Hexanal, nonanal, benzaldehyde, acetophenone, undecanal Esters Butyl butyrate, 3-methyl heptanol acetate, 2 acrylic acid 2 ethylhexyl ester, oxalic acid acrylate Others TV-butyl ether
Also, for monocyclic olefins cyclobutene
(Figure S25) has lower activation barrier than the cyclopentene (Figure S28); however, the cyclopentene leads to a less stable product than the cyclobutene
and 2-cyclohexenone has a lower activation barrier as compared to the parent ethylene.
Also discussed are the reactions of cascade cyclizations, heterocyclization involving enyne-carbodiimides, and new achievements in some classical cycloaddition reactions, such as the Diels-Alder condensation with acetylenic dienophiles, [2+2] cycloadditions with an acetylene component leading to the creation of a cyclobutene
ring, and new results in cyclobutene
syntheses by [2+2] acyclization of phosphorus containing 1,3-butadiene derivatives synthesized starting with propargyl-type alcohols.
The tendency of the [sup.29]Si chemical shifts among the acyclic tetrasilyldisilenes, 19, and 21 is parallel to that of the corresponding [sup.13]C NMR chemical shifts among ethylene ([delta] 123.5), cyclopropene ([delta] 108.7), and cyclobutene ([delta] 137.2), suggesting a similar origin for the tendency.
(30) However, it is hard to investigate the interconversion between cyclobutene 23 and bicyclobutane 24, partly because 1,3-butadiene is the most stable isomer among 22-24.
(33) Thermal isomerization of 27 to 28 is regarded to be complementary to the concerted isomerization observed among [C.sub.4][H.sub.6] isomers, because direct electrocyclic isomerization between bicyclobutane and cyclobutene is hard to be observed in the carbon systems.
The main components of the Lippia sidoides Cham, essential oil used in the present study were: cycloheptatriene, benzene, methyl-toluene, cyclobutene
, carvacrol and thymol.
In order to study the effect of unsaturation on the ring strain in small cyclic molecules, the conventional strain energies for cyclobutene
, azetidine-1-ene, phosphetane-1-ene, azetidine-2-ene, and phosphetane-2-ene are determined within the isodesmic, homodesmotic, and hyperhomodesmotic models.
Other copolymers such as those with cyclobutene
and cyclopentene are being developed.
He's best known (or would like to think he is) for his recent studies of the photochemistry of cyclobutenes
and other strained hydrocarbons of theoretical importance -- in spite of what the textbooks say, the photo-chemical conversion of cyclobutene
to butadiene apparently does not follow orbital symmetry selection rules!