Preparation of haloalkane

alvinhtleung

in the preparation of haloalkane :

2-methylpropan-2-ol+HCI(arrow)2-chloro-2-methylpropane+H20,some acid impurities will  left on the surface of the apparatus.Why is sodium hygrohencarbonate used to remove acid impurities,rather than a stronger alkali such as sodium hydroxide?

Zend

think of the chemical properties of haloalkane, then you can blow water

.•Ｈuｎg▊鴻

tips: elimination and substitution
think about the reactants of these 2 reactions

j32738

原帖由 Zend 於 20-9-2008 15:17 發表
think of the chemical properties of haloalkane, then you can blow water

答之前唔該諗清楚=.=
冇幾耐我做完個實驗我唔係咁答,但係岩左
Miss話你諗個方向係好多人常犯既錯

原帖由 .•Ｈuｎg▊鴻 於 20-9-2008 16:38 發表
tips: elimination and substitution
think about the reactants of these 2 reactions

都係上面個句

tip:諗下add NaOH同add NaHCO3 出既pdt有咩分別

Zend

原帖由 j32738 於 20-9-2008 05:58 PM 發表

答之前唔該諗清楚=.=
冇幾耐我做完個實驗我唔係咁答,但係岩左
Miss話你諗個方向係好多人常犯既錯


都係上面個句

tip:諗下add NaOH同add NaHCO3 出既pdt有咩分別

我覺得我想得arm bor
我記得係kinetic 都有做過similar reaction

HCO3- 同acid react? 

.•Ｈuｎg▊鴻

我可能chem根基唔好
不如你講下答案

j32738

我都係講我寫果個答案
加NaHCO3去remove HCl 有CO2出
加NaOH 係冇observable change
所以determine唔到幾時remove晒HCl

NaOH係唔會同haloalkane react,除非加熱

明未?

Zend

NaOH 唔會同haloalkane 反應? 加熱先得?
你肯定?

.•Ｈuｎg▊鴻

你呢個reason係岩
但唔係main pt.
無需要知道幾時先remove晒
2者都係in excess
最後都係用solvant extraction姐

NaOH係唔會同haloalkane react,除非加熱
呢句我非常有保留

Zend

如果有reaction => 就應該prevent 有excess ge sodium hydroxide/sodium bicarbonate

如果無reaction, 我大可以加到過量都無事... 又或者用#7 果招, solvent extraction, 整走bottom layer 果層haloalkane , then KO ...

我估reaction , 同#7 果個上part 都係原因, 而且係有關=.=

#7, arm arm check 番New Way, 係RTP 都有reaction for tertiary haloalkane....
大部分都係elimination reaction ~~