2-methylbutan-1-ol is heated with an excess of concentrated sulphuric acid (H2SO4) in order to cause an elimination reaction:
H3C-CH2-CH(CH3)-CH2OH + H2SO4 ==> H3C-CH2-C(CH3)=CH2
2-methylbutan-1-ol + concn H2SO4 ==> 2-methylbut-1-ene + water
1) Draw all of the above as displayed formula.
2) What is the product of this reaction?
2) Provide a ‘curly arrow’ mechanism (in displayed formula) for
the formation of the product supported with an explanation.
1)
----H--H--CH3--H -----------------------------O ----------------H ----- CH2CH3
-----I----I----I----I -------------------------------II -------------------\ -------/
H - C - C - C - C - O - H -- +----- H - O - S -O -H ==> ---- C = C ------ + how
-----I-----I----I----I ------------------------------ II ------------------/ ------ \ --- do I draw
----H----H---H---H -----------------------------O --------------- H ------- CH3 -- water
2) Is the product of the reaction:
2-methylbut-1-ene + water
Why does it ask for the product when there are two products. Why does it not ask what are the two products or what are the products?
As the answer for what is the product so I write:
2-methylbut-1-ene + water
3) ?
Why not ask for productS instead of product. The only person that can ask that is the author of the problem.
My attempt at H2O follows:
-----------H
------------|
------------O-H
The length of the vertical O-H bond and the length of the horizontal O-H should be the same but I have no control over that.
3. Can't do curly arrows or any other kind of arrows for mechanisms. Sorry about that.
2-methylbut-1-ene
Option 1:
-----H---H----------H
-----I-----I----------/
H - C - C - C = C
-----I----I----I------\
----H---H---CH3- H
Is the displayed formula for 2-methylbut-1-ene above right?
Option 2
----H---------H---H
-----I----------I----I
H - C = C - C - C - H
-----I-----I-----I----I
----H--CH3--H---H
Option 3
H-------H--------H
---\------I---------I
--- C = C - C - C - H
---/------I-----I----I
H-------H-CH3--H
These two structures above came up online.
Which ones are right?
3) Provide a ‘curly arrow’ mechanism (in displayed formula) for
the formation of the product supported with an explanation.
Do I copy the displayed formula I did for part 1 and then add arrows?
Where would I add the arrows if this is the case?
What would the explanation be?
------------H
------------|
------------O-H
Is this the exact way water must always be drawn when asked for its displayed formula?
3)
Step 1:
----H--H--CH3--H -----------------------------O
-----I----I----I----I -------------------------------II
H - C - C - C - C - O - H -- +----- H - O - S - O -H
-----I-----I----I----I -- .. ------------------------- II
----H----H---H---H --I --------------------------O
------------------------ --> H+
==>
-----H---H----------H
-----I-----I----------/ ---------------- H
H - C - C - C = C -------- + ----- I
-----I----I----I------\ -----------------O - H
----H---H---CH3- H --------------
=========================================>
----H--H--CH3--H ------------------------------O
-----I----I----I----I --------------------------------II
H - C - C - C - C - O - H -- +----- H - O - S - O -H
-----I-----I----I----I -- + ------------------------- II
----H----H---H---H -/ \ --------------------------O
-----------------------H H
==>
-----H---H----------H
-----I-----I----------/ ---------------- H
H - C - C - C = C -------- + ----- I
-----I----I----I------\ -----------------O - H
----H---H---CH3- H --------------
Step 2:
----H--H--CH3--H _ ----------------------------O
-----I----I----I----I -/--I-----------------------------II
H - C - C - C - C^ - O - H -- +----- H - O - S - O -H
-----I-----I----I----I -- + -------------------------- II
----H----H---H---H -/ \ ---------------------------O
-----------------------H H
==>
-----H---H----------H
-----I-----I----------/ ---------------- H
H - C - C - C = C -------- + ----- I
-----I----I----I------\ -----------------O - H
----H---H---CH3- H --------------
=========================================>
----H--H--CH3--H _ ----------------------------O ------------H
-----I----I----I----I -/--I-----------------------------II ------------I
H - C - C - C - C^ - O - H -- +----- H - O - S - O -H --- O -- H
-----I-----I----I----I -------------------------------- II
----H----H---H---H -------------------------------O
-----------------------
==>
-----H---H----------H
-----I-----I----------/ ---------------- H
H - C - C - C = C -------- + ----- I
-----I----I----I------\ -----------------O - H
----H---H---CH3- H --------------
=========================================>
Step 3
----H--H--CH3--H _ --------------------------O ------------H
-----I----I----I----I -/--I---------------------------II ------------I
H - C - C - C - C^ - O - H -- +----- H - O - S - O -H --- O -- H
-----I-----I----I----I +----------------------------- II
----H----H---H---H -----------------------------O
-----------------------
==>
-----H---H----------H
-----I-----I----------/ ---------------- H
H - C - C - C = C -------- + ----- I
-----I----I----I------\ -----------------O - H
----H---H---CH3- H --------------
=========================================>
----H--H--CH3--H ----------------------------O ----
-----I----I----I----I -------------------------------II -------
H - C - C - C - C - O - H -- +----- H - O - S - O -H ----- CH2 = CH2 --- H+
-----I-----I----I----I------------------------------- II
----H----H---H---H -----------------------------O
-----------------------
==>
-----H---H----------H
-----I-----I----------/ ---------------- H
H - C - C - C = C -------- + ----- I
-----I----I----I------\ -----------------O - H
----H---H---CH3- H
I got confused for question 3.
3) Provide a ‘curly arrow’ mechanism (in displayed formula) for
the formation of the product supported with an explanation.
-----------------CH3---------------------------------------------CH3
-------------------I-------------------H2SO4 ---------------------I
CH3 - CH2 - CH - CH2 - OH ======> CH3 - CH2 - C = CH2 + H2O
I saw online that someone put the H2SO4 in a different formula on top of the arrow. I did this for the formula that was written here too. Why is the H2SO4 put over the arrow instead of added before the arrow?
Is this what the displayed formula should look like for this question? Or was I supposed to draw everything out as the displayed formula was asked in the question?
Do I write out the sulphuric acid like below:
------O
-------II--------
OH - S - OH
-------II--------
-------O
3)
Step 1
-----------------CH3-------------------------------------CH3
-------------------I-------------------------------------------I
CH3 - CH2 - CH - CH2 - OH ==> CH3 - CH2 - CH - CH2 - +OH
--------------------------------- .. --------------------------------------------I
----------------------------------^ --------------------------------------------H
----------------------------------I
----------------------------------H+
=================================================>
Step 2
-----------------CH3 -^-____ ------------------------------CH3
-------------------I -----I ------I -------------------------------I ----+
CH3 - CH2 - CH - CH2 - +OH ==> CH3 - CH2 - CH - CH2
-------------------------------------I
-------------------------------------H
-------------------------H
--------------------------I
-------------------------O - H
=================================================>
Step 3
-----------------CH3__/
-------------------I -/-+^--------- ==> CH3 - CH2 - C (CH3) = CH2
CH3 - CH2 - CH - CH2
----------------------------------------------------------------H+
Is this correct?