[guybrush]

Hi,

I have named two compounds as Butanal and Propanoic Acid.

However on Butanal there is a Oxygen double bond on Carbon 1. Should i rename it Butan-1-al?

Same goes for Propanoic Acid, on Carbon 1 there is an O double bond. Should it be Propan-1-oic acid?

[Borek]

Hi Threepwood

Is this your compound?

[Schrödinger]

I have named two compounds as Butanal and Propanoic Acid.

However on Butanal there is a Oxygen double bond on Carbon 1. Should i rename it Butan-1-al?

Same goes for Propanoic Acid, on Carbon 1 there is an O double bond. Should it be Propan-1-oic acid?

You don't have to. Can you think of a possible structure for butan-2-al or propan-2-oic acid?

Maybe for clarity's sake, you might want to rename them. But it's not wrong to use either of the names.

[guybrush]

Hi Threepwood

Is this your compound?

Thats the one, I just have to supply the systematic name for it which is Butanal. Just do not want to get marked down for either not putting the number in or leaving it out. I have put the number in just so i understand the numbering of carbon chains.

My propanoic acid is: 2-Methylpropan-1-oic acid. 1 has the Oxygen double bond and 2 is the Methyl group.

Pleased to hear you have heard of Legendary Pirate Guybrush Threepwood :-)

Thanks for your help both of you.

[Borek]

Pleased to hear you have heard of Legendary Pirate Guybrush Threepwood :-)

I have LeChuck's theme as a ringtone on my mobile

[guybrush]

Pleased to hear you have heard of Legendary Pirate Guybrush Threepwood :-)

I have LeChuck's theme as a ringtone on my mobile

Have i told you about the time that i killed Ghost Pirate LeChuck with a bottle of Root Beer from Stan's Used Ship Emporium?

[guybrush]

This molecule attached, I have it down as 2 ethyl pentanal. However someone said it has a 6 carbon chain so its hexanal. Do i start from the Carbon Oxygen Double Bond? Or from the lower chain and follow it up and to the left so it is then a 6 chain carbon.

[cpncoop]

The compound you drew was 2-methylpentanal

[guybrush]

Hi,

Thanks for your reply.

How come it is methyl and not ethyl? As the chain i have comes up as C2H5. I get 2-ethyl pentan-1-al (pentanal)

[Arctic-Nation]

It is ethyl. I, too, had to double-check as the structure as you draw it can be a bit confusing.

And, just for the sake of it, 2-methylpropanoic acid is not the same as propanoic acid. Adding numbers to names that don't need them should be avoided at all times.

[guybrush]

Thanks for that.

[guybrush]

It is ethyl. I, too, had to double-check as the structure as you draw it can be a bit confusing.

And, just for the sake of it, 2-methylpropanoic acid is not the same as propanoic acid. Adding numbers to names that don't need them should be avoided at all times.

What is the reasoning behind it not being Hexanal? Do you always start from where that C=O double bond begins when you get a molecule like that?

[Arctic-Nation]

Priority rules can be rather daunting to apply correctly, but in simple molecules with only a few functional groups at most it shouldn't be too difficult. In this case, the aldehyde is the highest ranking group, so that's where you start counting. Next step is identifying the longest chain of carbon atoms (here, 5 atoms, including the aldehyde). The ethyl function is then another substituent. It's also the reason as to why this is not hexanal: there is no uninterrupted chain of 6 carbon atoms.

[Smrt guy]

You must always count the longest chain that includes the highest priority functional group (in this case the aldehyde).

[guybrush]

Thanks for clearing that up.