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Topic: Chiral Centres  (Read 6774 times)

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Offline mass

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Chiral Centres
« on: February 03, 2008, 10:57:32 AM »

Offline Kryolith

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Re: Chiral Centres
« Reply #1 on: February 03, 2008, 11:04:26 AM »
Welcome to the forum  :)

1) Circle the aromatic rings

Enalapril: 1 circle
Diazepam: 2 circles

2) Chiral centers

I hardly can see the asterisks, sorry.




Offline mass

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Re: Chiral Centres
« Reply #2 on: February 03, 2008, 02:10:58 PM »
its fine


8. Draw a structure for 3-chloro-2-ethylcyclopentanecarbaldehyde:


14. Explain why amides are the least reactive of the carboxylic acid derivatives in
nucleophilic acyl substitution reactions?
(5 MARKS)

18. The rate of ester hydrolysis can be increased by:
(a) decreasing the temperature of the reaction solution
(b) making the solution acidic
(c) making the solution basic
(d) both a and b
(e) both b and c



Can you help me with this question. Our uni has given the questions but not given a mark scheme so I am badly struggling, Its a question from a past exam paper. I am not asking you to my homework, bascially there is no guidance at uni at all. I am rather depressed and hence have joined on this site.

Offline Kryolith

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Re: Chiral Centres
« Reply #3 on: February 03, 2008, 02:32:16 PM »
A new post would have been better, but ok.


18. The rate of ester hydrolysis can be increased by:
(a) decreasing the temperature of the reaction solution
(b) making the solution acidic
(c) making the solution basic
(d) both a and b
(e) both b and c

What's the mechanism of an ester hydrolysis? Put up the reaction equations for the hydrolysis with an acid and for the hydrolysis with a base.

The temperature dependency of the reaction rate is described by the Arrhenius equation.

http://en.wikipedia.org/wiki/Arrhenius_equation

14. Draw resonance structures and/or argue using M/I-effects.

8. Precise your problem or post your proposal.

Offline mass

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Re: Chiral Centres
« Reply #4 on: February 03, 2008, 02:33:38 PM »
A new post would have been better, but ok.

18. The rate of ester hydrolysis can be increased by:
(a) decreasing the temperature of the reaction solution
(b) making the solution acidic
(c) making the solution basic
(d) both a and b
(e) both b and c


so is it b then?. Also what about the other 2 questions.

What's the mechanism of an ester hydrolysis? Put up the reaction equations for the hydrolysis with an acid and for the hydrolysis with a base.

The temperature dependency of the reaction rate is described by the Arrhenius equation.

http://en.wikipedia.org/wiki/Arrhenius_equation



Offline Kryolith

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Re: Chiral Centres
« Reply #5 on: February 03, 2008, 02:36:45 PM »
Why b and not a,c,d or e? Try to reason your answer.

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