Quick/brief Chem questions

[StringFever]

Hey guys,

Hope you're all having productive revision sessions for Chem. I know many of the questions I'm going to ask are dumb-sounding, but I hope you guys can help me!

1. When an alkene and water undergo an addition reaction (to form an alkanol), is a catalyst needed? And if so, what is a good example?

For example, in some alternate trippy world of mine I wrote that H3PO4 was required as a catalyst in the reaction between ethene and water to form ethanol? Was I right?

2. In a very similar vein, how do I determine states of matter for organic reactions/pathways? I'll contextualise my question by using two examples.

When ethanol is created from fermentation of glucose, the product is supposedly in aqueous form, however, when the same alkanol is formed from an addition reaction between water and ethere, the alkanol is apparently a liquid.

3. Suppose I have ethan-1,2-diol (semi-structural formula: OHCH2CH2OH) and I analysed it using a high resolution proton NMR, I will obviously have two peaks. What level of splitting would I get? See I thought it would be a single and a triplet (because of the n+1 rule), but according to the solutions set, it stated two singlets. Why is this?

4. Are double-bonds/benzene rings and the like counted as functional groups? What definition do I use when I describe a functional group?

[StringFever]

PS. I was so rude and forgot to say that any help would be appreciated and thanks for the suggestions in advance!

[TrueTears]

1. Yes at

2. When water and ethene react the alkanol should be (aq)...

3. is one environment and the H on the OH is another environment hence 2 peaks. would not split because the on the adjacent side is also in the same environment. H on the OH would not split because it is shielded by the O

4. No, benzene ring is not a functional group.

[StringFever]

Thank you TrueTears

It was quite odd because a practice exam of mine stated that benzene rings were a functional group. :S

[TrueTears]

Ain't the benzene rings just delocalised electrons which keep 'rotating'? So I'm not sure if I'd consider that to be a functional group.

[StringFever]

PS. TrueTears, can I say for high-res proton NMR that unless my environments are different, or if my hydrogen is next to an oxygen, that splitting won't occur (i.e. disregard the n+1 rule)?

[StringFever]

Oh and in regards to the benzene right, yes, I do agree

But I guess it comes down to what one defines a functional group...and I don't know how I'd define it personally.

[TrueTears]

Yes, if they are in the same environment and they are next to each other, no splitting occurs. If the hydrogen is shielded by a very electronegative element such as O, Cl, N etc then no splitting occurs.

[Mao]

Hydrocarbons with the same functional group will have similar chemical properties.

The phenyl group (benzene) can sometimes be considered as a 'functional group', but more often than not the benzene ring is the 'backbone' of the molecule itself. For example, you wouldn't say propyl in propanol is a functional group, benzene in xylene wouldn't be a functional group either.

It's very ambiguous.. =S

[StringFever]

Actually, I was attending a TSFX lecture last week, and the lady, Irena, said rather tongue-in-cheek:

If you have to write down benzene as a functional group, say:

"Benzene ring - it is widely accepted by many chemists to be a functional group, despite its rather erratic/on-off acceptance in previous VCAA papers"

So yeah, I think it is quite ambiguous