organic chemistry - Why and how does ring expansion occur in …
Why does this happen? This is because a four member ring has a high amount of ring strain. Expanding itself to a 5 member or (if possible) a six member ring is highly advantageous as it helps alleviate some of this ring strain. Now, in this case there is also the added advantage of the six member ring being aromatic (benzene).
organic chemistry - Question on ring expansion - Chemistry Stack …
2020年6月10日 · Why and how does ring expansion occur in the dehydration of (cyclobut-3-ene-1,2-diyl)dimethanol? Hot Network Questions How did the Dutch Republic get sufficient timber to build its navies?
organic chemistry - Ring expansion in cyclic compounds
2015年6月13日 · I believe is based on ring strain in this case, as the ring strain in a five-membered ring is ~$6.2\ \mathrm{kcal/mol}$, while the ring strain in a six-membered ring is ~$0.1\ \mathrm{kcal/mol}$. Source : Advanced Problems In Organic Chemistry, MS Chouhan, 11th edition; Chapter - Hydrocarbons (Alkenes); Question 180 in latest edition
organic chemistry - Ring expansion and carbocation formation ...
2016年5月27日 · To understand which rearrangement pathway is preferred, we must consider the relative stabilities of the intermediates.
organic chemistry - Carbocation rearrangement with ring …
2022年12月16日 · If the expansion takes place, then Bromine(an electronegative element) would apply -I effect on carbocation and will make it unstable but also 5 membered ring is more stable than 4 membered ring due to less angle strain. How to decide it then?
organic chemistry - Ring expansion in cyclo compounds
2020年7月4日 · In the following reaction, why does ring expansion not take place? Mechanism that was the correct one: In the second step when there is a protonated carbon the ring should expand to become 6 membered as that is more stable. This should be followed by a methyl shift from Quaternary to tertiary and then the $\ce{Cl}$ should get attached. But this ...
organic chemistry - Ring Expansion And Final Structure
2018年9月10日 · There are mainly two factors governing this phenomenon of ring expansion and rearrangement of carbocation, mainly Stability factor and Thermodynamic factor. When you have a carbocation which can rearrange within itself, it will definitely prefer a rearranged structure which has the highest stability.
organic chemistry - Acid Catalysed Ring Expansion – Mechanism ...
2018年3月21日 · Ring expansion of vinyl cyclobutane - Could someone please help me with a detailed mechanism for the above conversion? It is the acid-catalyzed rearrangement of 4,7,7-trimethylbicyclo[3.2.0]hept-3-en-6-one to 3,3-dimethyl-6-methylidenebicyclo[2.2.1]heptan-2-one. I couldn't find the mechanism anywhere, and couldn't propose a good one either.
organic chemistry - How do I decide whether ring will expand in …
2019年4月20日 · To sum up you can say that the cyclopentyl ring does not let cyclopropyl ring to provide stability to carbocation which makes ring expansion a preferred option. Edit3 (Bonus): I asked to my professor about this, he told me that there are two conformational isomers of cyclopropyl methyl carbocation.
organic chemistry - Carbocation rearrangement involving three …
2018年2月18日 · Unfortunately you have opened the can of worms that is cyclopropylmethyl carbocations. It is known that the parent unsubstituted cyclopropylmethyl carbocation is non-classical, and leads to mixtures of cyclopropylmethyl, cyclobutyl, and homoallyl derivatives.
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