But if you reverse the formula, you can't see immediately that it is related to propanoic acid. So for consistency you would need to reverse the formula of sodium propanoate - NaOOCCH 2CH 3. Salts are always named with the metal first - think of sodium chloride or potassium iodide. In the formula, the sodium is at the end, but appears first in the name. Note: The confusing thing about these salts (and even more so for the esters that are coming up next) is that they are named the wrong way round. In a shortened version, sodium propanoate would be written CH 3CH 2COONa or, if you wanted to emphasise the ionic nature, as CH 3CH 2COO - Na +. It's wrong, and makes you look very incompetent in an exam! Whatever you do, don't draw a line between the sodium and the oxygen. Notice that there is an ionic bond between the sodium and the propanoate group. When the carboxylic acids form salts, the hydrogen in the -COOH group is replaced by a metal. Propanoic acid is a three carbon acid with no carbon-carbon double bonds. This is the sodium salt of propanoic acid - so start from that. This time, not only is there a chlorine attached to the chain, but the chain also contains a carbon-carbon double bond ( en) starting on the number 3 carbon (counting the -COOH carbon as number 1).Įxample: Write the structural formula for sodium propanoate. In the old days, you would have had to learn the formula rather than just working it out should you need it.Įxample 3: Write the structural formula for 2-chlorobut-3-enoic acid. That name sounds more friendly, but is utterly useless when it comes to writing a formula for it. The old name for 2-hydroxypropanoic acid is lactic acid. You are forced into this alternative way of describing it. Normally, you would show that by the ending ol, but this time you can't because you've already got another ending. The hydroxy part of the name shows the presence of an -OH group. There is a methyl group on the third carbon (counting the -COOH carbon as number 1).Įxample 2: Write the structural formula for 2-hydroxypropanoic acid. This is a four carbon acid with no carbon-carbon double bonds. That carbon is always thought of as number 1 in the chain.Įxample 1: Write the structural formula for 3-methylbutanoic acid. When you count the carbon chain, you have to remember to include the carbon in the -COOH group.
Amino functional group full#
If in doubt, follow this link first.Ĭarboxylic acids contain the -COOH group, which is better written out in full as:Ĭarboxylic acids are shown by the ending oic acid. The names on this second page aren't explained in quite as much detail as those on the introductory page - it assumes that you have already understood the main principles. Note: If you haven't already looked at that page, it would be a good idea to do so before you go on. It assumes that you have already looked at the introductory page covering compounds from alkanes to ketones. This page continues looking at the names of organic compounds containing chains of carbon atoms. Understanding the names of organic compounds
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