1)Why can the use of high temperatures in the catalytic hydrogenation of alkenes to alkanes be self-defeating ?
2)Provide an explanation for the fact that all trans-1,2,3,4,5,6-Hexaisopropylcyclohexane is a stable molecule in which all isopropyl groups are axial.
112)Provide an explanation for the fact that all trans-1,2,3,4,5,6-Hexaisopropylcyclohexane is a stable molecule in which all isopropyl groups are axial.
Ans:- The shape of the isopropyl group is such that it fits more readily, and consequently with less steric interaction, when all the groups are axial.
11Is 2- Bromobicyclo[1.1.0]butane capable of existing as enantiomer?
I drew its structure and I think it is capable of forming enantiomer because 2 carbons (upper and below one) has 4 different groups attcahed.
just clear my doubt
11Maximum enolisation ka ek question tha, but I wanted to know the reason, because of this reason I can now solve other problem related to that. [1]
Thanks Prats [3][1]
39o-nitrophenol is most volatile because of chelate formation due to H-bonding(between oxygen of -NO2 and H of -OH).
Maximum enolisation? Any specific situation or is this a general question? The enol form is preferred if there is some stabilizing factor which gives greater stability than if the compound were present in keto form, for eg - aromaticity.
11Some more questions
a)What is the condition for the maximum enolisation to take place?
b)Which is most volatile isomer of nitrophenol ? why?
39Khyati, this image may help you to gauge the explanation of question 2 -:
And you've asked Q1 around in other forums also. I posted something similar on why elimination is favoured at higher temperatures...if I find the link of the thread I'll paste it here.
23remove all possible H, and then check the conjugate bases for each H.
the most stable base will result frm most acidic H.wat venkatesh said is correct , but only when all other important factors arent present.
but in a cyclopentadiene, resonance is possible. now when the H from sp3 carbon will be removed , we get a planar comp with 6 delocalised π electrons . hence the resulting anion is aromatic , which makes it highly stable.
11Arey but in the answer they have given the hydrogen attached to sp3 carbon acidic
See the arihant organic chemistry textbook, page no. 16 question no.4 (b) and (c)
1the H attached to the sp hybridized atom is more acidic than sp2 hybridized and sp3 hybridized....
Acidic order :
sp H > sp2 H > sp3 H
11Some more questions
3) How to know the acidic hydrogen in the compounds in which hydrogen is attached to the atom other than oxygen, for example in Cyclopent-1,3-diene?
4)Why only 4 water molecules are directly attached to one water molecule? I know its a stupid question, but I cannot think of a reason for it.
11@khyati yup the reason given by you is perfectly right.i asked it from a senior
111)Why can the use of high temperatures in the catalytic hydrogenation of alkenes to alkanes be self-defeating ?
ΔG = ΔH - TΔS
Because the higher the temperature, the more likely a dehydrogenation back to the alkene will take place!
http://www.chemicalforums.com/index.php?topic=43918.0
