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Showing posts from April 19, 2019

妖精森林的小不点

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Clash Royale CLAN TAG #URR8PPP 你好~!欢迎来到萌娘百科! 如果您是第一次来到这里,点这里加入萌娘百科! 欢迎具有翻译能力的同学~有意者请点→Category:需要翻译的条目← 如果您在萌娘百科上发现某些内容 错误/空缺 ,请 勇于 修正/添加! 编辑萌娘百科其实很容易! 觉得萌娘百科有趣的话,请推荐给朋友哦...

Cycloaddition

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Clash Royale CLAN TAG #URR8PPP A cycloaddition is a chemical reaction, in which "two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity." The resulting reaction is a cyclization reaction. Many but not all cycloadditions are concerted and thus pericyclic. [1] Nonconcerted cycloadditions are not pericyclic. [2] As a class of addition reaction, cycloadditions permit carbon–carbon bond formation without the use of a nucleophile or electrophile. Cycloadditions can be described using two systems of notation. An older but still common notation is based on the size of linear arrangements of atoms in the reactants. It uses parentheses: ( i + j + …) where the variables are the numbers of linear atoms in each reactant. The product is a cycle of size ( i + j + …). In this system, the standard Diels-Alder reaction is a (4 + 2)-cycloaddition, the 1,3-dipolar cy...