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- Joined
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I used some on my bike yesterday
E
EddieM
Well it's only contrived to unambiguously define the structure of the molecule. in this simple example the propane bit simply means that there are at most 3 carbon atoms in a row (it's not really like that, but that's a whole different kettle of fish) the dimethyl bit means there are 2 methyl groups (CH3) attached to the propane "backbone" and the 2,2 bit means they both come off the second carbon of the propane backbone.
Using "your" nomenclature for C5H12 tetramethylmethane, is ok in this case as it is unambiguous however for longer chain hydrocarbons it would run into ambiguity problems, as you couldn't determine which groups were attached to which carbons.
Using "your" nomenclature for C5H12 tetramethylmethane, is ok in this case as it is unambiguous however for longer chain hydrocarbons it would run into ambiguity problems, as you couldn't determine which groups were attached to which carbons.
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Yes, in a more general sense, I can understand that, but ....
Indeed, but I obviously was talking about 'this case', in which, as you say, it is unambiguous - as I presume it would also be in any case in which all the hydrogens of the hydrocarbon backbone had been substituted - for example (assuming that it exists!) ...
. CH3 CH3
. | |
CH3-C--C-CH3
. | |
. CH3 CH3
(I've given up trying to format that - see next post!)
... which I suppose I might call "hexamethylethane" - and which I imagine you would call something like 2,2,3,3-tetramethylbutane?
However, I presume that the/your point is that it is desirable to use nomenclature which is unambiguous in all cases - and I suppose I can't argue with that!
Kind Regards, John
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... how about this ...
Kind Regards, John
Kind Regards, John
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EddieM
2,3 tetramethylbutane.
Hmm, not quite technically correct, but not a bad stab, it's 2,2,3,3 tetramethylbutane, which on reflection make sense.
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Fair enough - I got pretty close (and, I think, 'unambiguously', even if my offering probably had some redundant numbers in it!)
Going back to the original issue, I suppose my thinking went a bit further than just nomenclature ... I don't know what, if anything, it means in terms of properties, but I "think of" the molecule as being 'methane with all four hydrogens substituted by methyl groups' (hence my "tetramethylymethane"), rather than as 'propane with the two single hydrogens substituted by methyl groups' (as per your "2,2-dimethylpropane").
Kind Regards, John
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EddieM
Fair enough - I got pretty close (and, I think, 'unambiguously', even if my offering probably had some redundant numbers in it!)
Going back to the original issue, I suppose my thinking went a bit further than just nomenclature ... I don't know what, if anything, it means in terms of properties, but I "think of" the molecule as being 'methane with all four hydrogens substituted by methyl groups' (hence my "tetramethylymethane"), rather than as 'propane with the two single hydrogens substituted by methyl groups' (as per your "2,2-dimethylpropane").
Kind Regards, John
Well it's true that a molecules structure can have massive implications, sad case to demonstrate is that of Thalidomide (don't ask to give me it's IUPAC name!) not isomers, but racemes, but the "R" form of it does exactly what is says on the tin, the "L" form causes terrible birth defects.
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To be fair, that in itself was no great surprise, given that, in general (and for whatever reason), the "R" forms of molecules tend to have much less (if any) biological/pharmacological effects than do the corresponding "L" forms - and that includes unwanted effects.
Kind Regards, John
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EddieM
Isn't that what I suggested in the first place?
Kind Regards, John
Yes, you did, but I confess I don't really know why 2,2,3,3 offers any more disambiguation than simple 2,3 hey ho!
I agree. As I wrote ....
Fair enough - I got pretty close (and, I think, 'unambiguously', even if my offering probably had some redundant numbers in it!)
Kind Regards, John
E
EddieM
Well, it's seems both are fine, seems chemical nomenclature is about as good as electrical "standards" !
Hmmm - as I think we have agreed, there is no ambiguity in either of the 'descriptors' of that molecule, but I think that's more than can be said of some things in BS7671!
Kind Regards, John
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