# Organic chemistry - alkanesWatch

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#1
What would you draw 3,3,3, tri methylheptane ? Also how would you draw 4,4,5 tri ethyl 5 propyl nonane
thanks
0
3 years ago
#2
(Original post by nisha.sri)
What would you draw 3,3,3, tri methylheptane ?
thanks
The numbers stand for the C-atoms, right? so we have the same functional group, the methyl-group (-CH3) on the third C-atom three times. Thus you have to draw this alkane in a way that three methyl-groups exist on the third C-atom.
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3 years ago
#3
3,3,3-trimethylheptane can't exist- are you sure it's the correct name?

For 4,4,5-triethyl-5-propylnonane, draw a carbon chain 9 carbons long- from the nonane part.
Then number the carbons (in this case, it doesn't matter which side you number from, but in other cases the highest priority functional group would decide which side to start from)
Then draw the ethyl and propyl groups at the correct carbons
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3 years ago
#4
nonane = 9 carbons
draw two ethyl groups on carbon 4 and one on carbon 5
draw a propyl group on carbon 5
"fill in" the hydrogens
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3 years ago
#5
(Original post by Poooky)
3,3,3-trimethylheptane can't exist- are you sure it's the correct name?
To OP: try drawing it (with hydrogens if you need to), and figure out why it can't exist...
1
3 years ago
#6
(Original post by FlowerFaerie087)
To OP: try drawing it (with hydrogens if you need to), and figure out why it can't exist...
It is because there are exist more than three carbon atoms in methylheptane and two bounds of four are needed to create the chain. Thus there just can exist two functional groups on every single atom at the maximum, not three.
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#7
(Original post by Poooky)
3,3,3-trimethylheptane can't exist- are you sure it's the correct name?

For 4,4,5-triethyl-5-propylnonane, draw a carbon chain 9 carbons long- from the nonane part.
Then number the carbons (in this case, it doesn't matter which side you number from, but in other cases the highest priority functional group would decide which side to start from)
Then draw the ethyl and propyl groups at the correct carbons
Oh no there was a structural formula and you had to name it
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3 years ago
#8
(Original post by nisha.sri)
Oh no there was a structural formula and you had to name it
Are you able to name those two structures?
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#9
(Original post by Poooky)
Are you able to name those two structures?
I know the first one but not the second for the second one I got 3ethyl 4metyl heptane
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3 years ago
#10
(Original post by nisha.sri)
I know the first one but not the second for the second one I got 3ethyl 4metyl heptane
That's correct for the second one
1
3 years ago
#11
(Original post by nisha.sri)
I know the first one but not the second for the second one I got 3ethyl 4metyl heptane
That's what I would have thought!
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3 years ago
#12
First one can't exist as you'd get a pentavalent carbon.
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#13
(Original post by Poooky)
That's correct for the second one
(Original post by worksmartnothard)
That's what I would have thought!
Oh ok thanks
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#14
(Original post by Poooky)
That's correct for the second one
This one was the one I was stuck on
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3 years ago
#15
(Original post by nisha.sri)
This one was the one I was stuck on
First of all you need to identify the longest carbon chain, if there's two of the same length, the correct one is that in which the highest priority group has the lowest number.
Once you've done that, then just number the chain as usual and identify the groups attached onto the carbons
Have you had a go at this one?
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#16
(Original post by Poooky)
First of all you need to identify the longest carbon chain, if there's two of the same length, the correct one is that in which the highest priority group has the lowest number.
Once you've done that, then just number the chain as usual and identify the groups attached onto the carbons
Have you had a go at this one?
Yeh i did but it doesn't exist haha
Do you have to number as usual ? My teacher didn't tell me to do that though
0
3 years ago
#17
(Original post by nisha.sri)
Yeh i did but it doesn't exist haha
Do you have to number as usual ? My teacher didn't tell me to do that though
What did she say?
You have to number as usual, but only after identifying the correct carbon chain. I admit I'm having difficulty with this as I'm not entirely sure which is higher priority!
What's the longest chain of carbons in this?
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3 years ago
#18
http://www.chem.uiuc.edu/GenChemRefe...ure_rules.html

Have a read; rule number 6 will be useful for this!
1
#19
(Original post by Poooky)
What did she say?
You have to number as usual, but only after identifying the correct carbon chain. I admit I'm having difficulty with this as I'm not entirely sure which is higher priority!
What's the longest chain of carbons in this?
(Original post by Poooky)
http://www.chem.uiuc.edu/GenChemRefe...ure_rules.html

Have a read; rule number 6 will be useful for this!
I did it again and i got 4,4 diethyl 5 propylnonane what did you get ?
9 is the longest carbon chain
0
3 years ago
#20
Try recounting... if there are two longest chains of the same length, priority goes to the one with the smaller substituents. There are five substituents!
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