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Current time:0:00Total duration:5:26

Video transcript

let's systematically name some carboxylic acid so let's say at a molecule that looked like that looked like this clearly a carboxylic acid we have a carboxyl group right over right over here now to name it systematically we do it just the way we've named our simple alkanes when we first learned how to name any organic molecule you look for the longest carbon chain and the longest carbon chain is one two three four carbons so our prefix will be Butte so it's butan and instead of calling it butane instead of writing this II hear we know this is a carboxylic acid it has this carboxyl group so we call it butanoic butanoic acid and now you might wonder hey don't we have to specify where the carboxyl where the carboxyl group is and if you look at how carboxylic acids are arranged you can tell the carboxyl group is always going to be at one end of a carbon chain so you don't have to specify in fact you always want to start numbering at wherever the carboxyl wherever the carboxyl carbon is so if you had to number these this would be the one carbon the 2 the 3 and the 4 so you don't have to specify a number for the carboxyl group let's do another one let's say let's say we had something that looked like this let's say we had something that looked let me put let me put another carbon on there just like that and let's say that there's a methyl group let's say that there's a methyl group right over there now clearly a carboxylic acid but to name it systematically we just want to find the longest carbon chain so we have 1 2 3 4 5 6 carbons so our prefix will be hex so it's hex and it is hex and it's clearly not just a hexane it's a hexanoic acid it has this carboxyl group right here this is hexanoic hexanoic acid and we're not done because we still have this methyl carbon right over here and it is on the we always want to start numbering at this carbonyl carbon 1 2 three four five six it is at the number three carbon so this is three methyl three three methyl hexanoic acid let's do one more let's say we had a molecule a molecule that looked like this let's see that's one two three four five six seven carbons and then we have our carboxyl group just like that and let's say that we had a double bond right over there what would we call this well once again look for the longest carbon chain longest carbon chain we have one two three four five six seven carbons so the prefix is hepped prefixes hep so it's HEPT and we won't just and actually let me be careful this isn't an alkane this has a double bond right here this has a double bond right over here so it's hep teen if this was just an alkene we would just call it hep teen but we're not going to put this last a here because this is a the carboxylic acid and to specify where that double bond is we need to start numbering every number start numbering at the carbonyl carbon 1 2 3 4 5 6 7 so you could either name this 3 hep diene and we'll I haven't finished it yet I haven't put this final over here or you could name it HEPT HEPT 3 een just like that this is the more typical one that you would see because it tells you okay this is we have a double bond and it's on it starts at the number 3 carbon goes from the 3 to the 4 carbon but this isn't just a regular alkene this is a carboxylic acid so instead of writing that final EE here for an alkene we write it as we have a carboxyl group right here so this is 3 hep D Noack hep D Noack acid and we are done and actually if you wanted to get really fancy on this one right over here you could see that these two carbons that are on the double bond so this carbon and this carbon it's kind of a range like this if you view this as let me draw it like this they both have other hydrogen's up there that we didn't draw they're implicitly there but if you wanted to rewrite or redraw this molecule you could draw it like this you have two carbons just like this this one has a hydrogen popping up like that that one has a hydrogen popping down like that and then this carbon this carbon over here has this big functional group over here we'll call that R so this is R and then this one over here I'll do it in green has this other functional group has these three carbons we could call that our prime these three carbons are our prime and if you look at it this way you like hey look the functional groups are on opposite sides of the double bond they're away from each other so if you wanted to you could also call this trans trans we could even write an italic trans 3 hep D Noack acid and this will specify that these guys are on opposite ends but this is only if you're assuming that I kind of drew it in the actual three-dimensional configuration in some way anyway hopefully you found that useful