final 2012 Q6D: (Z) or (E) forms of a pentene

Moderators: Chem_Mod, Chem_Admin

Phuong Pham 3G
Posts: 7
Joined: Fri Sep 26, 2014 2:02 pm

final 2012 Q6D: (Z) or (E) forms of a pentene

Postby Phuong Pham 3G » Fri Mar 13, 2015 12:42 am

The question asks for the line structure of (Z)-3-bromopent-2-ene but how do you draw a (E)-3-bromopent-2-ene?

Chem_Mod
Posts: 18913
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 737 times

Re: final 2012 Q6D

Postby Chem_Mod » Fri Mar 13, 2015 12:49 am

The groups attached to the double bond are:
-Bromine, ethyl (Br is heavier than C so Br takes priority)
-Methyl, H (C is heavier than H so methyl takes priority)

So we compare the locations of Methyl and Bromine. In (E) they are across, in (Z) they are the same side.

Neil DSilva 1L
Posts: 70
Joined: Fri Sep 26, 2014 2:02 pm

Re: final 2012 Q6D: (Z) or (E) forms of a pentene

Postby Neil DSilva 1L » Fri Mar 13, 2015 1:17 am

Here's a picture showing you both the E/Z forms of the molecule. I just took the molecule from the answer in the practice final and rotated it on its side to focus on the double bond. The stars indicate the priority molecule on either side of the double bond.
Attachments
IMG_9981.JPG

Chem_Mod
Posts: 18913
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 737 times

Re: final 2012 Q6D: (Z) or (E) forms of a pentene

Postby Chem_Mod » Sat Mar 14, 2015 12:37 am

Thanks for uploading it Neil!


Return to “*Alkanes”

Who is online

Users browsing this forum: No registered users and 1 guest