Naming Esters & prefix's (1 Viewer)

[Roobs]

i have this question "show the reaction between 1-pentanol and ethanoic acid, to produce the ester 1-pentyl ethanoate" and got thrown by the "1-" prefix on the ester

what is the effect of such a number in front of an ester, in terms of its structure?

thanks

 

[tennille]

Esters have the form R-CO-O-R. If the alkyl group is not attached to the end of the chain, then this can be denoted by placing the number prefixes 1, 2, 3... in front of the ester name. So basically, the number prefix just indicates where the alkyl group is located on the chain.

 

[Roobs]

:-/ im still confused.......where else would the alkyl group be located if it wasnt at the front of the chain? would it be an alky group branch on the alkanoate chain or something?......

 

[tennille]

Sorry, my previous explanation wasn't clear. An ester has the form R-CO-O-R' (not necessarily R-CO-O-R, as stated in my previous post) and the R' group is the alkyl group. When it comes to esters, the R' group is named first, followed by the R-CO-O part.

This website provides an explanation on the naming of esters and other functional groups:

http://en.wikipedia.org/wiki/IUPAC_nomenclature_of_organic_chemistry#Esters

Basically, for but-2-yl propanoate, the second carbon on the R' group (butyl) is attached to the ester group (R-CO-O), which is shown in a diagram in the website above. Hence the prefix "2". In your case, the first carbon on the R' group (pentyl) is attached to the ester group, hence the prefix "1".

 

[Roobs]

ahh..ok..im set now
thanks