esterification入面,alkanol+ester,我本書講果d alkanol 果-OH group都係許最側邊,如果果-OH group許中間由product叫?
順便畫果strucutal formula黎睇睇...
thx
esterification
2007-03-09 11:59 pm
回答 (2)
2007-03-10 3:01 am
✔ 最佳答案
咁就要睇下你個 -OH group 係第幾果carbon 度la, 例如 prop-2-ol + propanoic acidform 既係 2-propyl propanoate
果structural formual 係
CH3
|
CH3COO-CH3
|
CH3
2007-03-09 19:04:11 補充：
yahoo真係煩, 搞到d bond 錯佐......上下果兩個-CH3 應該係第三個C 度,即係我用引號括著果個:CH3COO-"C"H3你應該明la......
2007-03-13 15:24:38 補充：
sorry,我打錯佐d野,應該係 CH3CH2CO2"C"H-CH3-CH3"C" 呢個carbon 係o係個O到, 而兩個-CH3 就係o係果"C" 度.....佢果名應該係,2-propyl propanoic ,講明有三個C, 而果-OH痴佐係第二個C度
參考: myself
2007-03-10 12:03 am
First of all - a refulx system is usually CLOSED otherwise the solvent will evaporate over time! Reflux systems can be closed because there's a water condenser attached, which will condense the vapour of the solvent back into the reaction and hence, preventing the loss of products (if your product is volitale)
The reflux method will give you better yield of the final prodcut because of the above reason AND also, because of temp. of the reaction. To product ester from alcohol and carboxylic acid needs enough temp. to heat up otherwise the nucleophilic attack at the carboxyl carbon cannot be completed (not enough energy).
The test tube method is not hot enough and the alcohol starting material will be evapourated, meaning that the equilibrium cannot be pushed all the way to the product side. And not enough alcohol to react with the acid won't give you a good yield.
Hope that helps.
參考資料:
Me
volatile... 補充時間：2006-10-31 4:43
reflux...spelling mistake again
Closed systems are usually used in organic reactions, we close it up with a constant N2(g) flow to keep the water out of the reaction. 補充時間：2006-11-01 0:55
Likewise, the reaction of forming ester would probably done in a closed system in the lab - the water condenser will cool the vapour down back into the reaction. 補充時間：2006-11-01 0:55
You can't reflux something WITHOUT a condenser, then that's dangerous because under heat, the volitale solvent and products with heat up ripidly and blow up! 補充時間：2006-11-01 0:56
The reaction CAN be done in an open-top reflux system BUT your reactants will be more likely to evapourate over time due to air...unless if you have the heat on low to do the reaction, which in that case the reaction will be slow and incomplete. 補充時間：2006-11-01 0:58
When I say water, it's in fact the moisture from air Iøm talking about
The reflux method will give you better yield of the final prodcut because of the above reason AND also, because of temp. of the reaction. To product ester from alcohol and carboxylic acid needs enough temp. to heat up otherwise the nucleophilic attack at the carboxyl carbon cannot be completed (not enough energy).
The test tube method is not hot enough and the alcohol starting material will be evapourated, meaning that the equilibrium cannot be pushed all the way to the product side. And not enough alcohol to react with the acid won't give you a good yield.
Hope that helps.
參考資料:
Me
volatile... 補充時間：2006-10-31 4:43
reflux...spelling mistake again
Closed systems are usually used in organic reactions, we close it up with a constant N2(g) flow to keep the water out of the reaction. 補充時間：2006-11-01 0:55
Likewise, the reaction of forming ester would probably done in a closed system in the lab - the water condenser will cool the vapour down back into the reaction. 補充時間：2006-11-01 0:55
You can't reflux something WITHOUT a condenser, then that's dangerous because under heat, the volitale solvent and products with heat up ripidly and blow up! 補充時間：2006-11-01 0:56
The reaction CAN be done in an open-top reflux system BUT your reactants will be more likely to evapourate over time due to air...unless if you have the heat on low to do the reaction, which in that case the reaction will be slow and incomplete. 補充時間：2006-11-01 0:58
When I say water, it's in fact the moisture from air Iøm talking about
收錄日期: 2021-04-12 21:52:31
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070309000051KK01794