Chem既chiral,optical active問題

''chiral without chiral centre cannot be optically active" <----This is correct!!!

butanol is optical active because it has a chiral centre
butanol can write as butan-2-ol, CH3-CH(OH)-CH2-CH3
左面數起,第二個carbon就係chiral centre, it has -CH3 , -H , -OH , -CH2-CH3

2008-03-05 03:49:14 補充：
如果題目就咁比butanol, 通常你想個-OH group放係邊都得

又或者係butan-1-ol中, CH3-CH2-CH2-CH2OH,
最右面果兩個H atoms唔一樣(唔係指-OH group入面果個H atom)
因為hydrogen 係有isotopes, 1H, 2H (<-----數目字係H的右上角)

這只是我想到的唯一可能>

一般情況
chiral得就一定optically active(100%下用得)


有時唔係chiral不過都可以係optically active(呢個係exception casae, AL有考過 c=c=c 什麼的)
但係個出現率極低-.-

淨睇chiral想知個reaction之後有冇optically active
可以睇番佢行咩reaction
例如Sn 2就 仍然會有optically active
Sn 1就會有1:1 racemate產生(即係冇optically active)

1.如果一個molecule是chiral但無chiral centre咁仲係唔係optical active?
when compound and its mirror image are superimposable , then it is chiral.
When the compound is chiral, it must have a chiral centre. maybe you can not find out.
When compound is said to be chiral, it is optical active.
2.點解我睇書話&#39;&#39;without chiral centre cannot be optical active&#39;&#39;...但講到Sn2既時 後又話chiral既 butanol係optical active既？
Because Only a compound is chiral, it can be optical active and thus 話&#39;&#39;without chiral centre cannot be optical active&#39;&#39;
如果話得butanol 係chiral 咁佢就有chiral centre...咁就係optical active 了~^^~希望help 到u~

我唔知解唔解答到你，不過你最好搵下CC Lee 或者 K Kwong Notes

據我所知，基本上有chiral centre ge 都係 optical active，不過有例外，例如一d 有chiral centre 兼有plane of symmetry的 chemical。

回應你第一條，你講得一d都無錯。For example penta-2,3,diene

至於第二條，我唔係好明你想問咩，不過butan-2-ol 的確有chiral centre

希望我解答到你!

2008-03-05 21:38:47 補充：
不如你問下K Kwong 啦...=.=
唔好意思，小弟才sor學淺......