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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]
The compound is the prototypical antiaromatic hydrocarbon with 4 pi electrons (or π electrons). It is the smallest [n]-annulene ([4]-annulene).Its rectangular structure is the result of a pseudo [3] - (or second order) Jahn–Teller effect, which distorts the molecule and lowers its symmetry, converting the triplet to a singlet ground state. [4]
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.
Benzocyclobutene is a strained system which, upon heating to approximately 180 °C, causes the cyclobutene to undergo a conrotatory ring-opening reaction, forming o-xylylene. Since this process destroys the aromaticity of the benzene ring, the reverse reaction is highly favored. Thermal generation of o-xylylene from benzocyclobutene
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 ...
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.
Chemical substances or states can persist indefinitely even though they are not in their lowest energy state if they experience metastability - a state which is stable only if not disturbed too much. A substance (or state) might also be termed "kinetically persistent" if it is changing relatively slowly (and thus is not at thermodynamic ...