[Cally]

Identify the following polymer.

a.perspex
b.polystyrene
c.poly (vinyl chloride)
d. poly (hexachlorododecylene)

Our lecture told is the answer is D.
But I think the answer is suppose to be C.

What is the product in the Pd-catalyzed hydrogenation of 1,2-dimethylcyclopentene?

a.trans-1,2-dimethycyclopentane
b.cis-1,2-dimethycyclopentane
c. a misture of trans and cis-1,2-dimethylcyclopentane
d.1,2-dimethylcyclopentane

If anyone know the answer to those two question, can you include an explanation for me for me to understand the question thoroughly.

[Dan]

Polymer: I agree with your answer, C: poly(vinyl chloride)

Hydrogenation: Can you draw the product? How would you name it?

For hydrogenation info see a standard organic chemistry text or http://en.wikipedia.org/wiki/Hydrogenation

[Vidya]

I am in favor of your professor.He is right that it is poly (hexachlorododecylene)
check the monomer  unit here is not vinyl chloride.
Polyvinyl  has the monomer of ---(CH2CH2Cl)n---
second one :
You need to know the stereochemistry of addition on the double bond.It is cis addition , now draw the product and select your answer

[sjb]

I am in favor of your professor.He is right that it is poly (hexachlorododecylene)
check the monomer  unit here is not vinyl chloride.
Polyvinyl  has the monomer of ---(CH2CH2Cl)n---

Whilst I can see the argument for poly (hexachlorododecylene), I'm not sure it's the best name, as you don't have any locants for the chlorines. Can you not see that the vinylchloride unit is the simplest repunit here?

second one :
You need to know the stereochemistry of addition on the double bond.It is cis addition , now draw the product and select your answer

Are you sure it's *always* cis? Perhaps something like http://preview.tinyurl.com/cycloreduce may come into play (though this links to the cyclohexene reduction)?

[Borek]

I would go for PCV as well. Unless there are some good reasons to not to - like substantially different properties of poly (hexachlorododecylene) compared to poly (vinyl chloride). But I doubt they are different.

[Vidya]

I  still agree with the lecturer .Please follow the rules to name a polymer .

http://www.chem.qmul.ac.uk/iupac/rssop/ss06t08.html#p7

 

Yes I am pretty sure about the cis addition in this compound .

[Borek]

So the problem is - what is the oligomer? Quoting site you have linked to (bolding mine):

Constitutional repeating unit (CRU)

The smallest constitutional unit, the repetition of which constitutes a regular macromolecule, a regular oligomer molecule, a regular block, or a regular chain.

Hexachlorododecylene is far from being the smallest. As I wrote earlier - perhaps there exist some particular reason to specify chain length of oligomer, but as long as we don't know it, simplest name would be PCV.

Interesting, but ambiguous question.

[sjb]

Indeed, the more I think about it, could not "poly (hexachlorododecylene)" perhaps refer to something of the form -(CH₂CH[C₄H₃Cl₆])_n- or similar, there is only one "ene" in this name, which is where the backbone is. This may well have different properties to PVC

Rough sketch here, it's possible the chlorines could be in the backbone instead?