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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Rutherford on May 02, 2013, 08:09:18 AM

Title: Number of dideuterated biphenyls
Post by: Rutherford on May 02, 2013, 08:09:18 AM

1. How many dideuterated biphenyls (Ph-Ph) exist?
I counted: 2-2', 2-3', 2-4' (2-5' and 2-6' are the same as 2-2' and 2-3' when the ring rotates around the Ph-Ph bond).
Then 3-3' and 3-4' (3-2' is the same as 2-3'). And only 4-4' left. All together, there are 3+2+1=6 biphenyls, but the answer is 12. Where am I wrong?


2. Just another quick one: Which of the following compounds can be reduced by NaBH₄ to form an alcohol?
A) ketones B) aldehydes C) carboxylic acids D) esters E) ethers
Why only A and B? Couldn't it be C and D, too?

Title: Re: Number of dideuterated biphenyls
Post by: Archer on May 02, 2013, 08:48:22 AM

1) you can have both deuterium atoms on the same ring, i.e. 2-3, 2-4, 2-6 etc.

Title: Re: Number of dideuterated biphenyls
Post by: betterbesafehero on May 02, 2013, 09:18:00 AM

2) You should have read the following :

http://answers.yahoo.com/question/index?qid=20110422152757AApMx96

also

http://www.chemicalforums.com/index.php?topic=41067.0

Title: Re: Number of dideuterated biphenyls
Post by: Rutherford on May 02, 2013, 09:37:21 AM

Quote from: Archer on May 02, 2013, 08:48:22 AM

1) you can have both deuterium atoms on the same ring, i.e. 2-3, 2-4, 2-6 etc.

That's what I forgot. Thanks for the tip.

Quote from: betterbesafehero on May 02, 2013, 09:18:00 AM

2) You should have read the following :

http://answers.yahoo.com/question/index?qid=20110422152757AApMx96

also

http://www.chemicalforums.com/index.php?topic=41067.0

Thanks for the links. NaBH₄ isn't strong enough because of the sodium.