Author Topic: Help naming molecules with bonus question  (Read 51 times)

LilDookie

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Help naming molecules with bonus question
« on: December 30, 2012, 06:47:55 AM »
So, I'm still trying to learn the ins and outs of naming molecules. It may come as second nature to some of you, but it's not so simple for me. For instance, what's another name for MDA? The one I came up with doesn't sound right, methylenedioxybenzoethylamine, in fact I know it's wrong. How do I specify that it is a primary amine? I think learning to read ,write and speak chem is a huge part of getting chemistry over all. I would seriously be grateful for any tutoring or advice in this area.

Another thing I cant find the answer to and I have searched and searched and read my text books, is the structure of a particular amide. I do know it has a carbonyl, but I'm unsure about the positions of the N and H also bonded to that same oxygen, at least I think they are there, especially the N. But are they NOH, ONH, how? Reading my text book it looks like the N and H are on the carbon after the carbonyl, not actually part of the carbobyl. Fuck, I dunno.

Help?
 :-\
The cost of sanity in this society is a certain level of alienation.
-Terrence McKenna

Ferrum

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Re: Help naming molecules with bonus question
« Reply #1 on: December 30, 2012, 07:29:41 AM »
For the common names of molecules: names like methylenedioxybenzoethylamine, phenylacetone, benzyl chloride, etc, lots of reading and practice is probably the most effective way to learn. There is less of a formal rule system for these names.

A more formal (and hard to deal with) convention is IUPAC. Modern day papers, web apps, and books use this system. It will behoove a chemist to learn this system. I suggest learning the material from the attached file.

Also, check out chemicalize(dot)org . This is a useful site that translates webpages with IUPAC names onto them in to the corresponding webpages with chemical structures drawn on them.

I'm not quite sure what you are saying about the amide structure. An amide has a nitrogen bonded to the carbonyl carbon, not to the carbonyl oxygen. To name the amide that has a methyl group and an ethyl group on the nitrogen, we would say "methylethylamide" for its common name. You could have figured out that the nitrogen is bonded to the carbonyl carbon and not the carbonyl oxygen because oxygen only likes to have two bonds. If two are taken up by the double bond to its carbon, the oxygen is definately not going to be bonded to another atom. (it can happen, but these compounds are unstable and definitely would not ever be seen in a final product).

RoidRage

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Re: Help naming molecules with bonus question
« Reply #2 on: December 30, 2012, 08:35:04 AM »
Ferrum replied while I was typing my response and pretty much summed it all but still:

There are many ways to name particular molecules. Systematic nomenclature (IUPAC)  is used to avoid any confusion among in the literature and is the most basic way you can name a compound. MDA is ‘’ 1-(benzo[1,3]dioxol-5-yl)propan-2-amine ‘’.  Amphetamine is actually not a systematic name; it’s used to describe alpha-methylphenethylamine (IUPAC: 1-phenylpropan-2-amine). While not systematic names, classes of compounds are being named to simplify identification (benzodiazepines, Tryptamines, etc.)
So the clearest non-systematic way to name MDA is 3,4-methylenedioxyamphetamine. MDMA would be 3,4-methylenedioxy-N-methylamphetamine. The prefix ‘’N-‘’ is used to specify that the nitrogen atom is substituted.

‘’ methylenedioxybenzoethylamine’’ is wrong on many levels. First, There’s no way to determine where the methylenedioxy bridge is. Second, it’s not an ethylamine, but an isopropyl amine. Third, ‘’benzo’’ isn’t normally used as a prefix, ‘’phenyl’’ is (Hence phenethylamine). Alpha-Methyl-3,4-methylenedioxyphenethylamine is more correct but it’s overcomplicating for nothing.
For your information, MDA is also called safrylamine, which is a trivial name (Like aspirin for acetylsalicylic acid).

As for your amide, supposing it's the one I think it is,  it’s called a primary amide (It means that the nitrogen atom is only substituted with hydrogen atoms…Secondary means there is 1 substituent; Tertiary means there is 2).

PS: I tried explaining the best way I can, but I think it's evident english isn't my first language...

LilDookie

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Re: Help naming molecules with bonus question
« Reply #3 on: December 30, 2012, 04:57:24 PM »
Thanks guys, and Ferrum, I think I already have that pdf, but Ill take it again anyway. The problem with the amide is I brain fart and dont see the line to the right with the NH2 as being connected to that carbonyl carbon, but it is. Thanks for pointing that out.
The cost of sanity in this society is a certain level of alienation.
-Terrence McKenna