[cuongt]

i find it hard to name compounds even though i have read through my text book and noted it looking at the compounds i have no idea what to do first. is there steps to name compounds? if there is can you please help me.
                                              CH3    CH3
example:                                     l         l
b)CH2CHCH2CH2CH3.     b)CH3 --  C -- C -- CH3         
                                                 l         l
                                               OH      OH

[Albert]

In the former there is obviously a double bond at one end of the molecule.

I think the latter should have been

CH3-COH(CH3)-COH(CH3)-CH3

where you should highlight the two OH groups.

[cuongt]

b is wrong on the forum shift to right the top and bot. when i go to edit it it is rite. sumthing is wrong lol
and how come there are two topics? i only posted one..

[Borek]

b is wrong on the forum shift to right the top and bot. when i go to edit it it is rite. sumthing is wrong lol

It will be never OK. Forum uses proportionally spaced fonts. Even if you will have your structure correctly displayed on your computer, it can be displayed incorrectly on other machines, as it depends on the OS/font/browser combination. Use of fixed width (monospaced) font can help - see your message now.

[cuongt]

hey equation for b is right now did u change it??

[BaO]

naming organic compounds is really really complicated,i only can tell you the steps how to name the compounds from your example
a) there are 5 Cs, and a double bond (besides single bonds) so its name would be 1-pentene
CH2CHCH2CH2CH3
1     2    3   4    5

b)for this one there are 4Cs(we dont count CH3 branches) single bonds and group OH so the name should be ended by ANOL
its name would be  2, 3- dimethyl-2,3-butanol

i know that is a bad explanation , so dont be angry when you dont understand.

[Will]

b)for this one there are 4Cs(we dont count CH3 branches) single bonds and group OH so the name should be ended by ANOL
its name would be  2, 3- dimethyl-2,3-butanol

For naming it you just count the longest carbon chain which bao correctly indicated was 4.
Then name the remaining CH₃s as methyl groups so the correct name is 2,3-dimethylbutane-2,3-diol. There are two methyl groups so you say dimethyl, and 2 alcohol groups, so you say diol.
Is there any part in naming compounds you find particularly difficult?

This is the main thread so maybe continue posting there?

[wereworm73]

Generally, the first thing you do is find the longest continuous chain of carbons in the organic molecule.  Sometimes, there is a tie between longest chains; so as a tie-breaker, pick the one with the most substituent groups (groups branching off from the main chain).

Once you found your longest chain, find the end of the chain that's closest to a substituent group.  The carbon on that end is considered to be carbon 1.

After that step, it's a matter of adding the substituent groups to the name.



CH3    CH3
 l         l
CH3 --  C -- C -- CH3         
  l         l
OH      OH


BTW, the second one is actually 3-methyl-2,3-pentanediol.  The longest continuous chain of carbons on that molecule is 5, so it's a pentane derivative.  Like Will said, when you have 2 hydroxy groups on the organic molecule, it's called a diol so the suffix is -diol.  With the hydroxy groups at carbons 2 & 3 on the chain, this would be a 2,3-pentanediol.  There's also a methyl group at carbon 3, so this compound is 3-methyl-2,3-pentanediol.  

[Will]

the second one is actually 3-methyl-2,3-pentadiol.  The longest continuous chain of carbons on that molecule is 5, so it's a pentane derivative.  Like Will said, when you have more than one hydroxy group on the organic molecule, it's called a diol so the suffix is -diol.  With the hydroxy groups at carbons 2 & 3 on the chain, this would be a 2,3-pentadiol.  There's also a methyl group at carbon 3, so this compound is 3-methyl-2,3-pentadiol.

woops, I thought the CH₃s were supposed to be above the two middle carbons like at http://www.chemicalforums.com/index.php?topic=9498.0. If it is the way you interpreted it, then you are right, just that one carbon should be CH instead of CH3 and one should be CH2 instead of C.

[Donaldson Tan]

Cuongt: This is a warning. Do not double-post in future, especially in the same forum.

[cuongt]

i didnt double post.. i asked why it came up twice.

[Donaldson Tan]

OK. I take back my warning then. I merged both threads into one anyway.

[cuongt]

OK. I take back my warning then. I merged both threads into one anyway.

hehe kool