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Cyclobutene is an organic compound with the chemical formula C 4 H 6. It is a cycloalkene. It is a colorless gas that easily condenses. It is of interest in research ...
In organic chemistry, a cycloalkene or cycloolefin is a type of alkene hydrocarbon which contains a closed ring of carbon atoms and either one or more double bonds, but has no aromatic character. Some cycloalkenes, such as cyclobutene and cyclopentene, can be used as monomers to produce polymer chains. [1]
This distortion indicates that the pi electrons are localized, in agreement with Hückel's rule which predicts that a π-system of 4 electrons is not aromatic. In principle, another situation is possible. Namely, cyclobutadiene could assume an undistorted square geometry, if it adopts a triplet spin state. While a theoretical possibility, the ...
Monocyclic cycloalkenes are cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and so on. Bicyclic alkenes include norbornene and norbornadiene. Two more examples are shown below, methylenecyclohexane on the left and 1-methylcyclohexene on the right: Left: exocyclic double bond Right: regular double bond
For example, the aromatic species 1 can be reduced to 2 with a relatively small penalty for forming an antiaromatic system. The antiaromatic 2 does revert to the aromatic species 1 over time by reacting with oxygen in the air because the aromaticity is preferred. [15] The loss of antiaromaticity can sometimes be the driving force of a reaction.
Möbius–Hückel correlation diagram; two modes of butadiene to cyclobutene conversion. It has been noted that for every degeneracy along a reaction coordinate there is a molecular orbital crossing. [4] Thus for the butadiene to cyclobutene conversion, the two Möbius (here conrotatory) and Hückel (here disrotatory) modes are shown in Figure 5.
The discovery that [18]annulene possesses a number of key properties associated with other aromatic molecules was an important development in the understanding of aromaticity as a chemical concept. In the related annulynes , one double bond is replaced by a triple bond .
The four carbon atoms in cyclobutane are not coplanar; instead, the ring typically adopts a folded or "puckered" conformation. [2] This implies that the C-C-C angle is less than 90°. One of the carbon atoms makes a 25° angle with the plane formed by the other three carbons. In this way, some of the eclipsing interactions are reduced. The ...