No. Sal has it correct. Since there are 3 halogens connected to one of the carbons, we end up with 1,1,1-trifluoro. Alkyl halide nomenclature cares about first - the closest halogen on the longest chain and Second - the carbon with the most bonds to a halogen gets first priority.
That is just a lone hydrogen group and therefore it doesn't need to be mentioned during the naming process. Had the "H" not been written out it would be a methyl group.
For the second example, why do we name the fluorine first? In the bromo-chloro-fluoro sequence the bromo is first alphabetically. Why would that not be 1-bromo-1-chloro-2,2,2 trifluoro ethane?
he said start at the end with more things attached, alphabetical order only matters when you put them in order during naming, it doesnt influence which direction you count carbon from
sweet Sal! I was just about to request organic chemistry videos, and here they are! Are you going to do some biochemistry (proteins, carbohydrates, fats etc) videos? And also some biology videos on the digestive system would be really appreaciated. Thanks for the great work your constantly putting out there for all to use.
At 8:54 Sal says that double bonds have priority when numbering but don't constituents have priority over double bonds? 1.Has the lowest locant (or sum of locants) for the suffix functional group. Locants are the numbers on the carbons to which the substituent is directly attached.
@shanosan the C where the 3 F's are attached should really be C no. 1 because it has more halide substituents attached to it (3F's) compared to the other C which only has 2 (1 Cl and 1 Br)
when you add a second double bond to the 1st example, there can no longer be a methyl group or a bromo. i know thats not the point of the example but that might also need a correction.
During naming the hydrogen can be ignored, since it's assumed that all carbons are bonded to hydrogens unless written otherwise. However if you're going to write the chemical formula you'll want to include everything (even the hydrogen).
We do not represent "HYDROGEN" in branched form. [Its the standard convention] The end of the branch represent s a CARBON and since it still has space for 3 bonds left, we attach 3H so it becomes CH3
There are basic groups that you should know, methyl, ethyl, prop, but. They represent different numbers of carbon and hydrogens. For example methyl refers to a CH3 group.
Does it matter where you start number the carbons for 2-bromo-2-chloro-1,1,1-trifluoroethane? For instance, can it be 1-bromo-1-chloro-2,2,2-trifluoroethane?
The compound in question at 5:39.. What about the lone hydrogen at the end? Is that already assumed or is it something that we should just ignore? CF3CClBrH would invariably be different than CF3CClBr wouldn't it?
Because the substituents get alphabetized. So in this case, bromo comes before chloro because B comes before C in the alphabet. The ordering does NOT have to do with priority.
One is 1,1,2,2,2; another one is 1,1,1,2,2 : the latter is better since it gives smaller number, and I don't think the ascending order of number matters in naming that compound. What matters is the alphabetical order.
Why can't it be 1-bromo - 1- chloro - 2,2,2 triflouroethane? Why don't we number our carbons from the lowest alphabetically halogen? Since bromo comes before flouro.
wouldnt it be 1,1,1-trifluro-2-bromo-2chloroethane bc you have to name the chain with the greater number of substituents? or it would still be the same difference?
@wendy033081 what if the 2nd C that has 2 substituents had 3.... 2 bromos and 1 chloro... wold that become your 1 then? does the alphabet kick in there?
For your last example, you didn't specify whether to put in the oct- part anywhere in the nomenclature. Do you just disregard that & write diene to take its place?
Thanks for your great videos. I think for the last structure at the end of this video when there are 2 double bonds you need to change the numbering as well, so it would be : 4-Bromo- 2-chloro-5methyl-oct-2,4- diene.
you always name so that if you added up all the numbers you used to represent each halogen, you would get the structure with the smallest sum. basically, add the given carbon numbers together. if there is a number combo that is smaller, it is not numbered correctly
Don't alkanes have priority over halides? Therefore, #1 should be 5-bromo-7-chloro-4-methyloctane? The minimum sum convention only applies when there are equivalent priority groups, no?
I always ask , why does that happen? & Khan Academy justifies every step that he takes. Because of this, I am more likely to remember what to do when it comes to answering a question in a test because I KNOW why I'm doing it, it's not just some random step that I'm trying to remember. Thank-you Sir, and sorry teachers but your not always helpful or thorough ..
This is not the correct way to name these. People trying to learn organic nomenclature be careful. He's not alphabetizing them and there is no need for a dash "-" between the root chain prefix- and the suffix -ene. Or at least that is the case of my 2016 textbook. It's possible this video is just out of date; it was uploaded in 2010. Khan Academy is a wonderful source of education but be aware that this is not the current way to name these organic compounds.
![Hunxho - Ball Forever [Official Video]](http://i.ytimg.com/vi/nki9ZTF9Uls/mqdefault.jpg)
This was very helpful, no bromo
A week of learning summed up in 9 minutes. I wish class was like this.
Khan Academy rocks. He teaches so well online wonder how well he teaches live
Khan academy is the best....
No. Sal has it correct. Since there are 3 halogens connected to one of the carbons, we end up with 1,1,1-trifluoro.
Alkyl halide nomenclature cares about first - the closest halogen on the longest chain and Second - the carbon with the most bonds to a halogen gets first priority.
Mr.Salman, i Can't thank you enough :)
Khan academy is the best for learning
seriously, thank you very much!
That is just a lone hydrogen group and therefore it doesn't need to be mentioned during the naming process.
Had the "H" not been written out it would be a methyl group.
For the second example, why do we name the fluorine first? In the bromo-chloro-fluoro sequence the bromo is first alphabetically. Why would that not be 1-bromo-1-chloro-2,2,2 trifluoro ethane?
My question too.
he said start at the end with more things attached, alphabetical order only matters when you put them in order during naming, it doesnt influence which direction you count carbon from
sweet Sal! I was just about to request organic chemistry videos, and here they are! Are you going to do some biochemistry (proteins, carbohydrates, fats etc) videos? And also some biology videos on the digestive system would be really appreaciated. Thanks for the great work your constantly putting out there for all to use.
Hiii, what you doing now ?
I'm pretty excited to know
@PoleReseal Hiii, what you doing now ?
I'm pretty excited to know
really good video but please make a video on the functional group like alcohol etc.
At 8:54 Sal says that double bonds have priority when numbering but don't constituents have priority over double bonds?
1.Has the lowest locant (or sum of locants) for the suffix functional group. Locants are the numbers on the carbons to which the substituent is directly attached.
@shanosan the C where the 3 F's are attached should really be C no. 1 because it has more halide substituents attached to it (3F's) compared to the other C which only has 2 (1 Cl and 1 Br)
Thank you for the video, it really helps!
just no word to describe ur studies technique
when you add a second double bond to the 1st example, there can no longer be a methyl group or a bromo. i know thats not the point of the example but that might also need a correction.
You are my new hero.
During naming the hydrogen can be ignored, since it's assumed that all carbons are bonded to hydrogens unless written otherwise. However if you're going to write the chemical formula you'll want to include everything (even the hydrogen).
We do not represent "HYDROGEN" in branched form. [Its the standard convention]
The end of the branch represent s a CARBON and since it still has space for 3 bonds left, we attach 3H so it becomes CH3
There are basic groups that you should know, methyl, ethyl, prop, but. They represent different numbers of carbon and hydrogens. For example methyl refers to a CH3 group.
this style of learning is aslo good
Got it ! Thanx!
Which substituent will have more priority Iodine or ethyl ?
Given that he put the methyl group in position 5 because that way the halides would be closer to the beginning, I would say iodine.
PLEASE make a video on S,R and E,Z configuration.
@rinwhr they all need locaters. You can't assume that someone will know all three are on carbon 1. IUPAC.
Ggled a lot in ochem u helped a lot
@masterkill95
No, a lone hydrogen is just a hydrogen and in these cases it doesn't really matter. A methyl group has one carbon and 3 hydrogens.
khan academy the best
Thank you so much 💜
i found these videos of more use than my professors
fluorine have less priority in than chlorine why? Tell me priority order between halogens and ethyl also methyl please!
good one please answer
Comment is old, but I’m pretty sure it’s based on alphabetical order
I got a question. Why the second structure is not called 1-bromo-1-chloro- 2,2,2-trifluoroethane?
thank you sal
you're the best thanks
Does it matter where you start number the carbons for 2-bromo-2-chloro-1,1,1-trifluoroethane?
For instance, can it be 1-bromo-1-chloro-2,2,2-trifluoroethane?
I love you Sal c:
sir could you please tell when does elimination of halogenoalkanes not occur.
thank you very much
i get this, thank you
Add halogen compounds in tags .
do you have to put the 1,1,1 before the triflouroethane?
Thanks ALOT I stru
what about the hydrogren coming off C2 in 2-Bromo-2-Chloro-1,1,1-trifluoroethane?
The compound in question at 5:39.. What about the lone hydrogen at the end? Is that already assumed or is it something that we should just ignore? CF3CClBrH would invariably be different than CF3CClBr wouldn't it?
In alkyl halide which condition the elimination and substitution reaction takes place?
You use the chain with the alkene, even if it's shorter than another chain. The double bond has higher priority than the longest chain.
5:33
Why is it 1,1,1-trifluoro? Why couldn't you have done 1-trifluoro?
so single bond carbon has more priority than halide group ? or is there some other reason for halogen not getting to form the suffix
Would it be appropriate to name the alkene with the two double bonds as
5-bromo-7-chloro-4-methyl-2,4-octene
Kevin Miller no, since you want to have the smallest number.
@XDecagraphX You have to state where the halides are - as with any functional group. Implication isn't enough unfortunately.
yes
Isn't it call 1-bromo-1chloro-2,2,2 trifluoro ethane?? because according to the alphabetical order rule???
Why do we put 4-bromo before 2-chloro in the first case? Does bromo have priority?
Because the substituents get alphabetized. So in this case, bromo comes before chloro because B comes before C in the alphabet. The ordering does NOT have to do with priority.
Wouldn't the ethane example be chiral?
It has to be 1,1,1-trifluoro
nice sir
05:01 shouldn't that compound be 1-Bromo-1-chloro-2,2,2-trifluoroethane?
don't you start the numbering on the side with more substituents? i had the same question actually though
One is 1,1,2,2,2; another one is 1,1,1,2,2 : the latter is better since it gives smaller number, and I don't think the ascending order of number matters in naming that compound. What matters is the alphabetical order.
I think so too, the carbon with the sum of heavier substitutents gets precedence, I've been taught
That's a way of naming but generally you guide for the carbon with more halides in this case like Sal made it
I have a question. Why there is no "2 methyl" for the second chain?
I was thinking the exact same thing
cant we name the second one as 1-bromo-2-chloro-2,2,2trifluoroethane ??
Why can't it be 1-bromo - 1- chloro - 2,2,2 triflouroethane? Why don't we number our carbons from the lowest alphabetically halogen? Since bromo comes before flouro.
in college they thaught us to naming giving the priority ALWAYS to the substituent with priority function, not to the alkene or alkine
wouldnt it be 1,1,1-trifluro-2-bromo-2chloroethane bc you have to name the chain with the greater number of substituents? or it would still be the same difference?
tri- doesn't count
If there is a double bond they usually say ...Octa instead of Oct why is it so?
can we not write the first example as '4,2-bromochloro........ '
i mean I'm just asking
I love you, no bromo
#12
@wendy033081 what if the 2nd C that has 2 substituents had 3.... 2 bromos and 1 chloro... wold that become your 1 then? does the alphabet kick in there?
why is that automatically a methyl?
numbering*
what happened to the Hydrogen?????
For your last example, you didn't specify whether to put in the oct- part anywhere in the nomenclature. Do you just disregard that & write diene to take its place?
+katrinachuah You write it as 5-Bromo-7-Chloro-4-Methyl-"OCT'"-2,4-diene
do you use a mouse to write?
what is given more priority -halide or alkyl substituent
In the second molecule, do you not name the methyl on the second carbon?
+MegaTheDing thats not a methyl. methyl is CH3. thats just a hydrogen so you dont mention it
Thanks for your great videos. I think for the last structure at the end of this video when there are 2 double bonds you need to change the numbering as well, so it would be : 4-Bromo- 2-chloro-5methyl-oct-2,4- diene.
In the second molecule what would happen if they both had three halogen, how would you number the carbons?
you always name so that if you added up all the numbers you used to represent each halogen, you would get the structure with the smallest sum.
basically, add the given carbon numbers together. if there is a number combo that is smaller, it is not numbered correctly
what if you have an oct-3-ene and a chlorine on the 2nd carbon atom from the right side
from which side will you start counting
Don't alkanes have priority over halides? Therefore, #1 should be 5-bromo-7-chloro-4-methyloctane?
The minimum sum convention only applies when there are equivalent priority groups, no?
why cant we start naming the longest chain from Cl?
My question as well. Since Cl comes before Flouro
I always ask , why does that happen? & Khan Academy justifies every step that he takes. Because of this, I am more likely to remember what to do when it comes to answering a question in a test because I KNOW why I'm doing it, it's not just some random step that I'm trying to remember. Thank-you Sir, and sorry teachers but your not always helpful or thorough ..
sorry, 5-bromo-7-chloro-4-methyl-2,4-dioctene
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1-triflouroethane?!!?!
This is not the correct way to name these. People trying to learn organic nomenclature be careful. He's not alphabetizing them and there is no need for a dash "-" between the root chain prefix- and the suffix -ene. Or at least that is the case of my 2016 textbook. It's possible this video is just out of date; it was uploaded in 2010.
Khan Academy is a wonderful source of education but be aware that this is not the current way to name these organic compounds.
Jason This way is the older way to do it, but both are acceptable. This is the way my class primarily learned it.
My apologies. Thank you for pointing that out to me.