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有機-鹵烷 - Coggle Diagram
有機-鹵烷
甚麼是鹵烷
sp3的碳其中一個被鹵化物取代，HX
親和性取代反應
親和性取代三要角
LVG
將電子帶走且穩定
weakly basic
親電子劑
親核性分子
any molecule that has an unshared electron pair
親和取代的機轉
SN1
R=k[LVG]
影響速率因素
substrate
parallel carbocation stablity
TS energy is easier to overcome
to estimate TS energy:
Hammond-Leffler postulatae
2 more items...
polar solvent
charge separation
with higer dielectric constant
LVG
negative charge developed on LVG
better ability to stabilize negative charge
weaker base-->Better LVG
i->br->cl->f-
:red_cross:nucleophiles
carbocations
trigonal planar
stablity:
3>2>1
立體化學
racemization
trigonal planar carbocation has symmetry --->optical activity is lost
SN2
Substitute nucleophilic 2
R=k[LVG][nucleophiles]
立體化學
backside attack
inverted
concerted process
bond breaking and formation occur at the same time
影響速率因素
substrate---steric effect
1>2>3(大部分)
溶劑
protic
hydrogen attached to a highly electronegative atom
solvate nuclepophiles stongly
polar aprotic
solvate cations but not anions
Nu- is naked
very reactive
neclophiles
盡量偏極化
親和性正向於鹼性
in the same group
size越大 親和性越好
b-脫去反應
加入鹼性物質，把a碳旁邊的碳上的氫脫去，形成雙鍵
遵守Zasz法則，雙鍵連再有最多取代基數的地方
依反應類別分為
E1
3級反應
加入protic solvent
和碳楊離子形成有關
E2
1級主要反應
加入aprotic solvent