烯丙基的主要区别(main difference allyl) vs. 乙烯基(vinyl)

烯丙基和乙烯基是两种不同的有机官能团。两者都有C-C双键，但位置不同。在乙烯基中，C=C直接连接到链的其余部分。与乙烯基不同，烯丙基通过-CH2基团连接到分子的其余部分。这是烯丙基和乙烯基之间的主要区别。

什么是乙烯基(vinyl)？

Vinyl indicates the –CH=CH2 functional group, which can be formed by removing hydrogen from ethylene molecule. Therefore, the general molecular formula of vinyl compounds is R- CH=CH2, where R is any other group of atoms. Vinylic groups have sp2 hybridized carbon atoms. These compounds are very reactive, and readily polymerize to form vinyl polymers. Polyvinyl chloride, polyvinyl fluoride, and polyvinyl acetate are some examples of vinyl polymers. The Figure 1. Illustrates the mechani** of polyvinyl chloride synthesis.

图1.乙烯基自由基聚合机理

乙烯基化合物通常用于塑料**，因为它耐用、便宜等。此外，乙烯基还有许多其他用途，因为它能与各种添加剂和改性剂结合。

什么是烯丙基(allyl)？

Allyl indicates a functional group with structural formula H2C=CH-CH2-R, where R is the rest of the molecule. It c***ists of methylene bridge (-CH2-) in between the vinyl group (-CH=CH2) and the rest of the molecule. Therefore, allyl group contains sp2 hybridized vinyl carbon atoms and sp3 hybridized allyl carbon atom. The allylic carbon atom is more reactive than normal alkanes, and it can easily form a stable carbocation because it is adjacent to vinyl carbon that can delocalize electr*** to stabilize the positive charge. The Figure 2. Illustrates the resonance stabilization of allylic carbocation.

由于碳阳离子的稳定性，烯丙基化合物在反应过程中呈放射状形成中间体。例如，SN1反应。

烯丙基(allyl)和乙烯基(vinyl)的区别

一般分子式

烯丙基：一般分子式为RCH2CH=CH2。乙烯基通过–CH2–基团连接到分子的其余部分。

乙烯基：一般分子式为RCH=CH2。乙烯基直接连接到分子的其余部分。

碳骨架杂交

烯丙基：含有sp3杂化的烯丙基碳原子，与sp2杂化的碳原子相邻。

乙烯基：含有sp2杂化碳原子。

使用

烯丙基：烯丙基化合物是许多天然产物的前体，包括天然橡胶和生物合成的萜烯。

乙烯基：乙烯基化合物可以生产乙烯基聚合物，如PVC、PVF、PVAc等。

碳阳离子的稳定性

烯丙基：烯丙基碳原子由于电子离域作用可以形成稳定的碳阳离子。

Vinyl: Vinylic carbocati*** are very unstable due to lack of p-character.