Esters

as ethane-1,2-diol has two alcohol groups on it, when you react with ethanoic acid, it will form a ester link betweens both molecules, because carboxylic acid reacts with alchol to form ester bonds, if you dont understand me just ask and ill explain it better

(edited 11 years ago)

Reply 2

a hint, the structural would be CH3COOCH2CH2OOCCH3 ill let you work out the displayed

little diagram

(edited 11 years ago)

Reply 3

OP

Original post by mattcandy3

a hint, the structural would be CH3COOCH2CH2OOCCH3 ill let you work out the displayed

little diagram

Thanks, but I still don't really understand where the two extra carbons come from?

Reply 4

i cant explain it in words so ill draw a nice diagram :biggrin:

Reply 5

So in the normal esterification process with just 1 OH group you will receive an ester ( ethyl ethanoate) which has 4 carbons, this is because, 2 carbons in the alcohol and 2 in the acid, so 4 altogether,

However with the ethane 1,2 diol there are 2 OH groups, therefore it will react with the acid twice , so you will have ester bonds on both sides of the molecule so 2 carbons from the original alcohol and 4 come from the acid that has reacted with the OH groups on either side of the alcohol

Reply 6

OP

Original post by mattcandy3

So in the normal esterification process with just 1 OH group you will receive an ester ( ethyl ethanoate) which has 4 carbons, this is because, 2 carbons in the alcohol and 2 in the acid, so 4 altogether,

However with the ethane 1,2 diol there are 2 OH groups, therefore it will react with the acid twice , so you will have ester bonds on both sides of the molecule so 2 carbons from the original alcohol and 4 come from the acid that has reacted with the OH groups on either side of the alcohol

I see! That makes much more sense now :smile:

Reply 7

yeah so 2 from each, however as it has 2 OH groups it will react again with ethanoic acid, creating another ester link, therefore it will gain another 2C from the acid , GLAD i could help, if you have any other problems just ask

(edited 11 years ago)

Reply 8

OP

Original post by mattcandy3

So in the normal esterification process with just 1 OH group you will receive an ester ( ethyl ethanoate) which has 4 carbons, this is because, 2 carbons in the alcohol and 2 in the acid, so 4 altogether,

However with the ethane 1,2 diol there are 2 OH groups, therefore it will react with the acid twice , so you will have ester bonds on both sides of the molecule so 2 carbons from the original alcohol and 4 come from the acid that has reacted with the OH groups on either side of the alcohol

Out of curiosity do you happen to know the nomenclature? Can the Oxygen double bond be a ketone? (Sorry if I'm asking a lot of questions - we've just covered esters but nothing to this sort of level).

Reply 9

NO, if they gave this molecule and asked you to name the function groups and you put ketone, you would be wrong, whenever you see double bond oxygen then an oxygen it is an ester group

(edited 11 years ago)

Reply 10

OP

Original post by mattcandy3

I dont really get what you are trying to ask, but NO, if they gave this molecule and asked you to name the function groups and you put ketone, you would be wrong, whenever you see double bond oxygen then an oxygen it is an ester group

By "nomenclature" I meant the name of the compound (if that's what you didn't understand). Also I'm talking about the other double bond, not the COO bond which defines it as an ester.

Reply 11

No you wouldnt need to need the ketone, (one) in there, i believe the name would be ethane-1,2-diyl diethanoate, (but i gather you are AS) so you will probably not be required to name any esters which have more then one ester bond ( like this one )

(edited 11 years ago)

Reply 12

OP