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Offline psychoNOT

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Help with interpreting molecular names
« on: December 04, 2009, 12:07:47 AM »
I have a problem which gives 3 names and I have to draw structures for them and then give names which would be more apt (easier to understand)
There are 3:

a) 1,4-di-1(1-methylethyl)benzene
b) 2-(prop-2-enyloxy)prop-1-ene
c) cyclohexa-1,3,5-triene

I know c is benzene (and I can draw it.. obviously), but I'm a little stuck on the first two.

For a, the base structure I know is benzene, but the first part is confusing me.  Does methylethyl mean propyl?  I know the 1,4 is telling me it will be para something benzene but the di and methylethyl is confusing me.  The repeated 1's are what is really getting me.  Does this mean on carbons 1 and 4 will be a methylethyl (propyl) group?  If so then I know how to draw it, and I would call it para-propylbenzene?  It sounds right to me and makes sense, just a little confusd about how exactly I would know that.

For b, I think the base structure is propene with a double bond on the first carbon, and then on the second carbon there is a propyl group attached.  Then the propyl group has a double bond on the 2nd carbon (-ENyl), but is it to the oxygen or to the carbon (not the carbon on the propane, the third carbon on the propenyl group).  So perhaps it would be 2-methylbut-1-en-3-one?  But that isn't much simpler so I don't think its right.  Any hints are appreciated.

Offline Dan

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Re: Help with interpreting molecular names
« Reply #1 on: December 04, 2009, 04:24:34 AM »
The first one makes no sense to me (or ChemDraw), could there be a typo?

Perhaps 1,4-di-(1,1-dimethylethyl)benzene would be 1,4-di-tert-butyl benzene?

For the second one, the prop-2-enyloxy residue is derived from prop-2-en-1-ol
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Offline sjb

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Re: Help with interpreting molecular names
« Reply #2 on: December 04, 2009, 07:56:40 AM »
Di-1(1-methylethyl) could also mean di-(1-methylethyl) - or di-isopropyl, perhaps?

Offline psychoNOT

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Re: Help with interpreting molecular names
« Reply #3 on: December 04, 2009, 12:12:11 PM »
My apologies.  Yes the first one is actually 1,4-di-1(1-dimethylethyl)benzene.  So for the second one you mean it would be propane with a double bond and an O on the 2nd carbon?  I get the 2nd one now I think... but if it's 1,4 on a benzene then perhaps it could be named para-tert-butylbenzene?  SJB I think it's definitely butyl (so does the book) because it's 1-dimethylethyl which would give mean 4 carbons, but I think I see where you're coming from.  OK so I broke down and looked at the answers... yes the 2nd one they said is para-t-butyl benzene, I understand that.  The 3rd one is diallyl ether... still a bit confused about how one would get there.  I see the prop-1-ene would give propane with a double bond on the first carbon, and then I get that the prop-2-enyloxy is just the propenyl attached to an O, but shouldn't it be 3-(prop-2-enyloxy), because the O of the prop-2-enyloxy in diallyl ether is definitely not attached to the 2nd carbon.

Offline sjb

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Re: Help with interpreting molecular names
« Reply #4 on: December 06, 2009, 11:56:36 AM »
The 3rd one is diallyl ether... still a bit confused about how one would get there.  I see the prop-1-ene would give propane with a double bond on the first carbon, and then I get that the prop-2-enyloxy is just the propenyl attached to an O, but shouldn't it be 3-(prop-2-enyloxy), because the O of the prop-2-enyloxy in diallyl ether is definitely not attached to the 2nd carbon.

If it were diallyl ether then yes, but it doesn't have to be. What does the prop-2-enyl radical look like?

Offline psychoNOT

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Re: Help with interpreting molecular names
« Reply #5 on: December 06, 2009, 10:12:49 PM »
Wow... so I also misprinted that one.. it is 3-(prop-2-enyloxy)prop-1-ene.  So mystery solved.  My simple mistakes are giving me much difficulty.  But SJB, I know the prop-2-enyl group is a simple saturated 3 carbon chain with one double bond.  What do you mean when you say "it doesn't have to be".  It doesn't have to be diallyl ether?  Or that the O could be attached to the 2nd carbon?

Offline sjb

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Re: Help with interpreting molecular names
« Reply #6 on: December 07, 2009, 01:56:50 AM »
It doesn't have to be diallyl ether?  Or that the O could be attached to the 2nd carbon?

Perhaps as an exercise draw out what you think 2-(prop-2-enyloxy)prop-1-ene looks like?

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