Ch. 6 problems help

[Mitch Marubayashi]

Hi all,

I have struggled a little with the owl problems for chapter 6 and am looking for some help.  If anyone could give me any help for the following problems I would really appreciate it:

6.5 This problem asks to draw the reactant that creates the product shown.  I don't understand why either of my first two attempts are wrong! 
http://imgur.com/CGzls
http://imgur.com/H0HqM


6.8  This problem has a bromine or chlorine addition and asks for the intermediate and then the product.  For the intermediate, I opened up the alkene at the double bond to create the bridged bromium ion intermediate per the example, with the charge on the bromine, and then from there draw an arrow and draw the product, which is given.  I'm not sure what I am doing wrong, I don't know what's wrong with my intermediate or products.

6.13 This question I need to discuss, it really stumps me.
http://imgur.com/fb9eO

6.14 This question I don't get what is wrong with my answer, except possibly that I left out a resonance arrow.
http://imgur.com/2g4G1

6.18 This one also looks like it's correct to me, also except it doesn't have a resonance arrow.
http://imgur.com/atiCf


Thanks.

Best,
Mitch

[Matt Cranshaw]

Hey Mitch,

6.5 In both answers you gave, you could also put the double bond somewhere else in the reactant, so you should have had two answers for both of those, not one. in the alkene, it could be on carbon one as well, and in the cyclo-, it doesnt have to be in the chain. put it on the methyl group.

6.13 I got this wrong. What you are saying sounds good. I think its a Marvin issue.

6.15 this is just two ozonolysis reactions occurring in the same molecule. use the longest of the three chains as a "parent" chain of sorts and connect the double bonded oxygens to give double bonds in your reactant. I think there might be some trans/cis things we cant really predict, but it took the one answer I gave so I dont think its picky here.

6.14 There are not isomers here because although hydrogenation is stereoselective, the carbons in questions have 2 of four bonds to hydrogens, so they are not stereocenters. 

6.18 You drew the ss and rr isomers, whihc is correct. I think they want you to draw the hydrogens accurately, and yours are in the same plane as the carbon chain and on the wrong side of the carbon chain. I bet if flip over and use the dash/wedge bonds, youll get credit. 

Hope this helps. I just took a quick glance at these, so I might be wrong on some of it.

Matt

[Mitch Marubayashi]

Thanks Matt, that really helped.

[Lauren Klingman]

Hey Mitch,

 

For number 8 make sure you don't just draw the first intermediate but also what is going to react next, for instance draw the intermediate and then draw the meOH and a reaction arrow forward. Owl will add in the plus. After the reaction arrow just draw the literal second intermediate (not with HCl or anything). Hope that helps.

 

Lauren

[Matt Cranshaw]

thanks lauren. couldnt do it before reading your post

On Monday, July 16, 2012 2:05:09 PM UTC-7, Lauren Klingman wrote:

Hey Mitch,

 

For number 8 make sure you don't just draw the first intermediate but also what is going to react next, for instance draw the intermediate and then draw the meOH and a reaction arrow forward. Owl will add in the plus. After the reaction arrow just draw the literal second intermediate (not with HCl or anything). Hope that helps.

 

Lauren