how to distinguish but-1-ene and but-2-ene?

Question

as in CHEMICALLY

Answer 1

But- is prefix for 4-carbon structure

-ene is suffix for double bond

number refers to beginning of double bond

thus but-1-ene has double bond between number 1 and 2 carbons and but-2-ene has double bond between 2 and 3 carbons.

Chemistry rocks!

Answer 2

But-1-ene

Answer 3

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RE:
how to distinguish but-1-ene and but-2-ene?

Answer 4

OK...if your question is how do you tell the difference in the formula, then it's as follows:

But-1-ene is CH2=CHCH2CH3 . You start numbering in such a way that the 2 C atoms having the double bond have the lowest numbers, so in this case, you start from the left. So the double bond is between C1 and C2. You choose the lower number of the 2, which is C1....so but-1-ene.

But-2-ene is CH3CH=CHCH3. In this case it doesn't matter where you start numbering from (left or right) because in both cases the double bond turns out to be between C atoms C2 and C3. You choose the lower number of the two, i.e. C2....so but-2-ene.

If your question is how to distinguish between them in the lab, then I'm afraid this is more complicated, since both of them are gases at room temperature....one of them boils at -6.1 and the other at +1 degrees C. The only reliable way is to react them with ozone.....but-2-ene will give ethanal as a product, and but-1-ene will give methanal and propanal. The aldehydes are then derivatised with 2,4-dinitrophenylhydrazine and their melting points determined...this will tell you which aldehyde you have, and hence what the original alkene was.

Answer 5

already u got a cool answer buddy...

again....
in the formulae..
In But-1-ene
the Double bond ll in the 1 st carbon to the second carbon..
In But-2-ene
the double bond in between 2 and 3...

but in lab it may be difficult...
very little change in their physical and Chemical properties makes it dificult...

Answer 6

These are isomers of one another: isomers have the same molecular formulae but they have different structures.

In but-1-ene the functional group, which is c=c (carbon carbon double bond) is on the first carbon from either side

in but-2-ene the functional group (c=c) is in the second carbon from either end

Answer 7

first obtain corresponding alcohols of but-1-ene and but-2-ene,the alcohols pbtained would be butan-1-ol and butan-2-ol

add lucas reagent to it(zinc chloride and hydrochloric acid)....but-2-ene gives turbidity immediately but but-1-ene takes a lot of time to give turbidity

Answer 8

A modification to the claudef answer:

Start with ozonolysis: When but-1-ene reacts with ozone we get a mixture of methanal (HCH=O) and propanal (CH3CH2CH=O). Neither of them reacts with alkaline solution of iodine (NaOH + I2).

When but-2-ene reacts with ozone the product is ethanal (CH3CH=O). Ethanal reacts with NaOH + I2 and we get a yellow precipitate of iodoform (CHI3):

CH3CH=O + 3I2 + 4NaOH --> CHI3 + HCOONa + 3NaI + 3H2O

Answer 9

but-1-ene C-C-C=C

but-2-ene C-C=C-C

we can distinguish them by ozonolysis using ozone + Zn/H2O

but-1-ene gives :
one molecule of propanal(CH3CH2CHO) and one molecule of methanal(HCHO) on ozonolysis


but-2-ene gives:
two molecules of ethanal(CH3CHO) on ozonolysis


Zn is used to prevent the further oxidation of methanl,ethanal,propanal to corresponding acids

Answer 10

but-1-ene on ozonolosis gives methanol and propanol while but-2-ene produces ethanol only.