nancy9494 Posted February 24, 2018 Share Posted February 24, 2018 better late than never? Why does the OH leave in the 4th step? why does this need to happen? thanks in advance Link to comment Share on other sites More sharing options...
hypervalent_iodine Posted February 24, 2018 Share Posted February 24, 2018 Because otherwise how do you form the ester? You could also consider reaction kinetics and thermal stability, but I think that might be a more complicated answer than you're looking for. Link to comment Share on other sites More sharing options...
nancy9494 Posted February 24, 2018 Author Share Posted February 24, 2018 I just don't understand why it can't chill in 3rd form. I can memorize the mechanism but I'd prefer to know. Link to comment Share on other sites More sharing options...
hypervalent_iodine Posted February 24, 2018 Share Posted February 24, 2018 Because there's acid present. The OH is easily able to coordinate a H+ from this, which turns the OH into water (a very good leaving group). 1 Link to comment Share on other sites More sharing options...
BabcockHall Posted February 27, 2018 Share Posted February 27, 2018 @OP, Which is a better leaving group, hydroxide ion or water, and why? Link to comment Share on other sites More sharing options...
nancy9494 Posted March 1, 2018 Author Share Posted March 1, 2018 The water because it is under acidic conditions? Link to comment Share on other sites More sharing options...
BabcockHall Posted March 1, 2018 Share Posted March 1, 2018 All else held equal, stronger bases make poorer leaving groups than weaker bases. Strong bases are less able to stabilize negative charge than weaker bases. Which is the stronger base? 1 Link to comment Share on other sites More sharing options...
nancy9494 Posted March 1, 2018 Author Share Posted March 1, 2018 the OH Link to comment Share on other sites More sharing options...
BabcockHall Posted March 1, 2018 Share Posted March 1, 2018 I would put a minus sign on it, to indicate that it is hydroxide ion. And we can compare the pKa values of the conjugate acids of any two leaving groups to determine which base is stronger. 1 Link to comment Share on other sites More sharing options...
nancy9494 Posted March 2, 2018 Author Share Posted March 2, 2018 ahh yes thank you Link to comment Share on other sites More sharing options...
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