h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Ah , it looks like I missed you by an hour, and now your email address has disappeared. Hallo? Anybody there? I've got a disastrous assignment...

Hello

Of course you can, fire away.

Ah , I've just missed you again!

I've nearly finished it now and it's due on Monday and I can't remember what I wanted to ask!

Okay. Um...it's probably too late, but I'll ask. If my questions are dumb or make no sense, just me.

What is/are the functional group/s in acetylsalicilic acid? I got a carboxyl group and a acetyl group (?), is that right?

With laevo- and dextro- forms, are they written with brackets and symbols like (+)-tartaric acid and if so, is (+) the dextro one?

Do you know of any isomers of caffeine? If it's 1,3,7-trimethylxanthine is it possible for things to switch around so it's something like 1,4,7-trimethylxanthine? If isomers of some organic compounds aren't naturally found, they can still exist in theory and I can still draw them, right?

What are the functional groups in glycerol? Is it just -OH?

The teacher has set the question: "What are the effects of the functional groups on some of the compounds in your examples?" My examples are stuff like glycerol, citric acid, tartaric acid, aspirin, polystyrene and cellulose. I've just gabbled on about the different functional groups and the physical characteristics of stuff within that group, do you think that makes sense?

Is it true that "Acetyl group (-COCH3) is formed when a carboxyl group (COOH) replaces its hydroxyl (OH) ending with methyl (CH3)."?

I think I've harassed you enough now...sorry...and thanks very, very much.

Also, is there a functional group called methyl group that's CH3 and present in caffeine?

Ooh, this is all much more advanced than I was expecting.

Lets see.

'What is/are the functional group/s in acetylsalicilic acid? I got a carboxyl group and a acetyl group (?), is that right?'

Yep (That's Aspirin to you and I by the way)

With laevo- and dextro- forms, are they written with brackets and symbols like (+)-tartaric acid and if so, is (+) the dextro one?

Yes and Yes

Do you know of any isomers of caffeine? If it's 1,3,7-trimethylxanthine is it possible for things to switch around so it's something like 1,4,7-trimethylxanthine? If isomers of some organic compounds aren't naturally found, they can still exist in theory and I can still draw them, right?

I'd have to look up the structure of caffeine myself I'm sorry to say but what you say sounds perfectly true. Make sure there is an available place on position 4 to stick your methyl group though (ie. a hydrogen atom to swap it with if you see what I mean). My job is to make those missing isomers which only exist in theory so yes you are right - as long as they conform to correct bonding theory of course (you can't have five groups on carbon for example).

What are the functional groups in glycerol? Is it just -OH?

Yes and there are three of them

The teacher has set the question: "What are the effects of the functional groups on some of the compounds in your examples?" My examples are stuff like glycerol, citric acid, tartaric acid, aspirin, polystyrene and cellulose. I've just gabbled on about the different functional groups and the physical characteristics of stuff within that group, do you think that makes sense?

Sounds fine to me. Carboxylic acid groups are acidic (oddly enough ) and so make things taste sour.


Is it true that "Acetyl group (-COCH3) is formed when a carboxyl group (COOH) replaces its hydroxyl (OH) ending with methyl (CH3)."?

Mmm, you have drawn a ketone here which is not really a derivative of a carboxyl group. Acetic acid CH3CO2H becomes CH3CO2CH3 when you replavce the H of the OH group with CH3. The CH3CO2- group is called an acetate group. Acetyl is CH3CO- where the OH has been removed so to form acetyl from acetic acid then you have merely removed the OH group.


Hope that helped

Orcus

Sorry, from my last point there I would in fact say that the functional groups in aspirin are an acetate group (or ester might be better) and a carboxylic acid.

Yes, methyl is a functional group and I believe there is one in caffeine.

So, how did you do then?

Looked like top marks to me

Believe me, some of our guys at university doing degrees in chemistry can't do some of the stuff you just whacked out.

Thanks very, very much. It was very helpful, as I managed to see it on Sunday. I struggled through it, and ended up with 48/50 which is all right. I screwed up the test, which was a couple of weeks ago, just under 70%, because I couldn't explain adequately why solubility in water with alcohols (I think) decreased as their number of Carbons increased, or draw some weird ester with some dodgy name that was like beeswax. Anyway. Cool. We're over the chemistry now, but I've stupidly signed up to do it next year. I may change, as next year is the start of the important years...sort of like A-Levels I guess.

Niwt

Nice one

You have yet do the A level equivalent???!!! The school chemistry is much more advanced Down Under than it is here then. That stuff was at least A level standard here.

Good luck with it all anyway - just drop by and ask away if you ever need help again.

No, I have the end of this year (a few weeks) and two more years before university, so I think I'm doing GCSE equivalent, or something.

Unfortunately next year I don't think it will be organic, but it will probably be easy, so I may still bother you.

The stuff we were doing in class wasn't quite as advanced as the assignment I asked you about though, assignments just extend.