Help!

[sam0001]

How many isomers of butanol are there?

Do we need to account for molecules that containing an ether group? Eg, CH3CH2OCH2CH3

[Tonychet2]

an ether isnt an isomer of butanol or any alkanol at vce level

but for butanol theres 4,

1-butanol
2-butanol
methyl-1-propanol
methyl-2-propanol

[pi]

Yep, the fact that it asks you for the isomers of butanol in the questions stem and not isomers for a given molecular formula implies that all of the isomers must be alkanols of some sort

[sam0001]

I'm confused! Does that mean if they asked us for isomers of a carboxylic acid, we would name the carboxylic acids oly and not the esters?

[pi]

I'm confused! Does that mean if they asked us for isomers of a carboxylic acid, we would name the carboxylic acids oly and not the esters?

Sorry I should have been a bit more specific when I wrote that!

This only applies to alkanols (and usually alkenes too)

[sam0001]

So if they asked us for isomers of C4H10O, we would include ethers and ketones? Ect..

How'd you know that butAnol implied all isomers are alkanols?

[sahil26]

So if they asked us for isomers of C4H10O, we would include ethers and ketones? Ect..

How'd you know that butAnol implied all isomers are alkanols?

Well Alcohols have one Oxygen atom. Therefore it's not an ester or ketone.
And  Butane has 4 carbon atoms... so that way you know that it is butanol. The easiest way to identify and remember isomers is drawing structural formulas...I suggest you try drawing structures until you can visualise them into your head.
Butanol had four isomers :
1-butanol
2-butanol
methyl-1-propanol
methyl-2-propanol

[sam0001]

...that's not what I meant.

I meant, how does one know that isomers of butanol include alcohols only?

In my sac the other day we were required to draw isomers of alcohols including ether groups.

[sahil26]

All Alcohols end with "ol" eg, methanol, propanol, butanol.

Therefore when it says Butan"ol" ... they are only talking about alcohols..

Carboxyl acids end with : "oic" acid
Esters end with : "oate:

[sam0001]

Ahh, I see. But isomers of carboxylic acids are esters too? Don't think the same rule applies there.

[charmanderp]

Aren't there different kinds of isomerism? Functional group isomerism is an entirely different thing to isomerism where the carbon chain is manipulated or substituents/functional groups are moved to different positions. Doesn't VCAA usually specify what exactly they want in relation to isomers?

[pi]

Aren't there different kinds of isomerism? Functional group isomerism is an entirely different thing to isomerism where the carbon chain is manipulated or substituents/functional groups are moved to different positions. Doesn't VCAA usually specify what exactly they want in relation to isomers?

Yep, they should, to prevent students form drawing random molecules (some of which are quite amusing).

[sahil26]

Ahh, I see. But isomers of carboxylic acids are esters too? Don't think the same rule applies there.

Esters are made by a condensation reaction between alcohols and carboxylic acid.
Their functional group is "COOC"

As i said before, They end with "oate".
Their names are derived from the alcohol and carboxyl acid they are formed from.
e.g. Methanol + Ethanoic acid = Methyl Ethanoate + H2O.

I hope you can see how the name is derived. The Alcohol becomes "yl" i.e. Methanol becomes Methyl, and Ethanoic acid becomes Ethanoate.

Hence, Propanol and Butanoic acid would form : Propyl Butanoate and don't forget the water molecule that is ejected.

[charmanderp]

Except for in the case of something like aspirin.

[Tonychet2]

Ahh, I see. But isomers of carboxylic acids are esters too? Don't think the same rule applies there.

carboxylic acids and esters arent isomers because a carboxylic acid has more hydrogens that an ester with the same amount of carbons

edit: nevermind i just drew a structure lol turns out they have the same

but either way they arent isomers lol