Naming alkenes examples | Alkenes and Alkynes | Organic chemistry | Khan Academy
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Naming Alkenes Examples. Created by Sal Khan.
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For all the people confused, in the next video Sal says that he made a mistake on this video because when he put two double bonds, he should have put diene instead of just ene.
8:21 *For all the people confused also, I believe this one ( **8:21**) should be called 2.3.5 - **_trimethyl-cyclohex-1-ene._** We should use the name where, when the numbers in that name are added, you'll have the lowest possible sum.*
after all that im still confused
Yes...
Joseph Gonzales 😂
yehhhh just as i thought ...thanks!
I guarantee the last one is 1,4,6-trimethylcyclohex-1-ene.
2,3,5-trimethylcyclohexene is INCORRECT because if there is a substituent on one of the double bond carbons, it gets number 1. Please don't get a wrong idea that the lowest sum of numbers takes a precedence over the rule mentioned previously. The lowest sum of numbers is NOT absolute in all cases. Check the 2nd page of www.vanderbilt.edu/AnS/Chemistry/Rizzo/chem220a/alkenes.pdf if you cannot believe me or use ChemBioDraw to get the program to name it for you.
1,2,4-trimethylcyclohexene is INCORRECT because when naming alkene a subsequent number must cover the other side of it.
Hope this clarifies everything.
Ur correct the reason for this is when u start numbering from one end on the the double bond u have to go the other end of the double bond, even he said that in the video
+Yeong Won Kim the parent chain can omit #1 since with ONLY one double bonding for alkene ,we know that it's priority!
Exactly, but about the first rule he mentioned, he is right
when I watch your videos I start having anger and rage towards my actual chemistry teachers. they make things way harder.
I also think the last question should have been 2,3,5-trimethylcyclohexene
Hi，I agree with you.So the number should be the smallest?
@@lesg1987 yes
2,3,5-trimethyl cyclohex-1-ene?
This is the correct IUPAC name
That's what I was thinking as welll
Sal: "Hopefully you find those useful"
Sir I find them all useful and thank you for making this subject finally understandable!
How do you find them useful?
Like what is the point of learning all of these
I am having hard time understanding what would be the usefulness of all of these
All the confusion ive had in the last three weeks of class Ive just easily learned cause of khan academy. THANK YOU
Its incorrect, you didnt include the "di" in 2,4 heptadiene. Its misleading
I think tha last question should be answered as 1,2,4-cyclohexene
Always remember choose the numberings with smallest sum
I learned my one week of chemistry in 1 hour. The videos were so good that I watched 10 of them continuously. Excellent
khan academy you save my life
do some people say hept 2,4 DI-ene? Di-ene is sometimes used in my chemistry class but i still haven't figured out where it fits. thanks for your videos
yea its 2,3,5-trimethylcyclohex-1-ene because like everyone mentioned it's a combination of counting the double bond as a starting point and counting sum of the lowest number of methyl groups. the rule is not to start where the methyl group is just start at a point in the double bond and count around if you have (1+4+6= 11 then 2+3+5=10) then the obvious solution is 2,3,5.
I love you and your videos. My test will be that much easier now (:
Khan Academy is so informative!!
aren't we following the lower locant sum rule in the last example? shouldn't it be 1,2,4-triMethylcyclohexene?
I have been watching the organic chem videos since yesterday and these videos have really helped me understand organic chem, so thank you so much :)
“Hopefully you find those useful”
Yes my 9th grade to college life is safe thanks to these
Yes it the 1,4,6 is correct. The alkene needs to be carbon 1 and 2, and the methyl group on the double bond dictates which carbon is number 1.
I cannot stop watching!!!! I'm addicted to your videos Sal. May God bless you.
@caustin19 I'm in Canada, and here, we were taught that it's the first point of difference (rather than average branch numbers). Numbering the way Sal did, The first methyl branch is numbered 1. Going the other way, the first branch wouldn't come up until you reached the second Carbon. That's the first point of difference and you should favor having the branch on your first Carbon, rather than your second.
The funny thing is, you're right. I get more intuitive knowledge from these videos in 10 minutes, than I do during a whole quarter of class.
Ok., I am hooked... these are great...
For the 2nd compound, can't the name also be 2,4-heptadiene?
yes you are correct, the 2nd compound is called as 2,4 - heptadiene because it contains 2 double bond
Its wrong....2,4-diheptene
Hept 2,4 diene
As others have pointed out, the second one is in fact 2,4 -heptadiene or hept-2,4-diene.
Thank you for the video
QUESTION ;-; how would it be if the double bond was in a substituent rather than the parent chain?
And by the way, the 1 in 1,4,6-trimethylclohexene is lower than the 2 in 2,3,5-trimethylhexene, thus the video is more correct. Each number is looked at individually, not as a whole so you don't add them or anything. If the first number is the same, you move on to the second to determine which is lower and so forth. Hope that helps!
Thank you
That was really useful for me
I think last example should be 2,3,5-trimethylhexene
Cyclohexene*
Berkay ŞAHİN I have the some result
Berkay ŞAHİN yeah you're definitely right, you can use lower substituent numbers that he does in the video.
Berkay ŞAHİN yeah I was going to ask, are both correct ?
Berkay ŞAHİN No, that is incorrect. www.vanderbilt.edu/AnS/Chemistry/Rizzo/chem220a/alkenes.pdf
If you check the second page, It says: if there is a substituent on one of the double bond carbons, it gets number 1
this saved my life just had to share
Same goes for me. I suggest following your professor's way of labeling, since s/he would be grading you. But it's useful to know other methods as well! :)
it should be the lowest form which is what you stated. Easy way of remembering is by numbering, and then adding up the numbers at which there is a bond to a methyl/ethyl/whatever, and which ever combination is lowest would be correct.
Very educational and useful video
for the last problem, isn't it better if you start numbering Clockwise so I'd be like 1,2,4-trimethylclyclohexine instead of 1,6,4?
The double bond HAS to be between carbons 1 and 2 in this ring, so the numbering in the video is correct.
Actually, when numbering, your highest priority is the substituent over the double bond. Therefore, he had to start with the 1 and go the counter clockwise direction. I think he's right.
@peaceloveandchips no the video is correct. you dont need 1-ene because cyclohexene implies that already.
thanks this really helps i got chemistry exam this week and i finally understand this
In my O-Chem class, the professor taught us that the sum of the #'s should be as low as possible. So 1+4+6=11, whereas 2+3+5=10. So I agree with the answer being 2,3,5-trimethylcyclohexene. Let me know though which method is more correct!
@caustin19 Actually, he's correct. Since the methyl group is at the carbon bond, it must be the 1. And also, the carbons of a double bond must be numbered consecutively, which means that the 2 is placed at the other end of the double bond (as labelled correctly in this video).
Sir,
Best videos seen so far on youtube about Organic chemistry.
You are explaining it in a very clear way which actually makes chemistry enjoyable again !
Keep up the good work,
and much thanks for your investment and help to students in need :)
@Mor S hey because the 2nd to last chain has double bound we use Di="2"
Thumbs Up If U Want This Gr8 Teacher Was Your Teacher In School!!
Thank you very much! As usual, Khan Academy is the only site I can understand! Thank you very much! :)
But what to do when an alkyne or alkene is a substitute...this condition may arise when we have functional group in the compound so we give more preference to the FG...anyone pls help
The second example should be 2,4-heptadiene
***** or hept-2,4-diene
According to my prior notes...after.double.bond the substitutes are give priority .......!!! So it ... should have been
1,2,4-Trimethylcyclohexene
my answer Sal is 2,3,5 trimethylcyclohexene
10th grade Biochem actually paid off!!
Thanks so much. This has been very useful. I understand now why the name should be diene..
8:14 Why not "2,3,5-TrimethylCyclohex-1-ene? I know that the double bond takes precedence but shouldn't
we try to make the other substituents have the lowest number as possible?
Thatnk you sooooo much. This helped me alot
It's diene when there's 2 double bonds! Awesome videos btw :)
in previous video eg:4 , if i have equal number of carbons in ring and well as in chain, what do i have to prefer first??
Thank you! I'm finally learning..but what kind of name did you put? is that IUPAC, derived name or common name??
Love these short movies, but i think it should be 2,3,5-trimethyhexene, because you want to keep to the lowest possible # around the hexagone. thus i think the numbering should start at the other end of the double bond and work clockwise. It might be different in the US thought.
my professor is teaching it by puttin the number in front, so on the first one, 2-heptene
I thought you were suppose to number the bonds from left to right. Is there a reason why he numbered from right to left? Please help🙏🏽
Hopefulle you found that...umn...useful...
Excellent lesson SAL!!😊
ohhh!! i understand it now! thank u so muchh!! This is sooo lovely!!
My organic professor never taught us the Hept-2-ene... We've only learned 2-Heptene...
thank you may god bless you 😍
Years passed and now they name *diene, triene ....* if more than one double bond is present. 😅😅
Btw dont these molecules have the E and Z isomers? And if so why didn't Kahn name it? Is there a specific reason or does he just not do it here?
Very good video
I love this guy! Thanks man!
Keep up the good work
i have a problem... whats the condence structure of "4,4-heptadiene" and its skeletal
can u do a video for alkyne
Thank you it is very help full.
thank you this is very helpful
thank you very much
@aerosmith0816 I 2ND THAT. but it's hept-2,4-diene, not hepta
Very well done, thanks xx
great, so far so good.
Shouldn't it be 2,3,5-trimethylcyclohexene (lowest numbering)?
you are the best teacher :D
excellent explanation. I get it now :-)
it can be either way
the correct name for the second one is 2,4- hepta"Di"ene
at 5:56 in your video why isnt the name Hept-2-ene2methyl?
shouldnt the second one be 2,4 hepatdiene??
wonderful thank you
@passmelers if u take it from the other side it is correct!!!
Thanks from PH 💕
Sir a mistake by you. Just check it. You have numbered the last diagram i.e. the cyclohexene structure incorrectly. The final result should be 1,2,4-trimethyl cyclohex-1-ene.....just check once because your positions of methyl groups are not appropriate.
for the 1,4,6-trimethylcyclohexene shown, what will happen if the double bond is at the 2nd carbon and 3rd carbon?
For the last hydrocarbon, wouldn't it be more accurate to use 2,3,5- Trimethylcyclohexene instead of 1,4,6- Trimethyl cyclohexene. As 1,4,6 reaches beyond 5 and accordingly we should be using branches which number to the least amount.
The rule is to use the set of numbers that has the lowest number at the first point of difference. 1 is a lower number than 2, so the name given in the video is correct.
I thought it had to be in alphabetical order Cyclohexene-1,4,6-Trimethyl I am so confused and I need to pass my C
hem class!
awsomly exlained dude :D
keep up the good work! looking forward to seeing more of your vids.
thanks :')
This was really helpful! Thank you :)
How
amazing videos sal, great job!!!
Tx men I love it this video
@aerosmith0816 That is true.
Maybe you should listen to one of his grammar lessons.
can it be expressed as 'hept-2,4-diene'?
Thanks bro
Why wouldn't your second example be 2,4-heptADIene?
we have to follow the double bond, not the methyl group
you're the best 😊
hello
thanx! this is a great video!! very understandable but why did u wrote H3C-CH2-CH2... why not CH3-CH2-CH2...?