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Having really big problems with organic chemistry work!

Hello. I was ill last week, so as a result missed alot of my lessons - unfortunately for me, they covered all of alkenes, which seems to be quite a complicated topic.

I have to catch up some work, and I have been ok with some of it, but there are a few questions which are puzzling me.

One of these is:

Methlypropene is reacted with concentrated sulphuric acid and then the product is warmed in dilute sulphuric acid, where hydrolysis occurs. Outline the mechanism occuring and namy any organic compounds which are produced during the process.

I really just have no idea what to do here!

Thank you very much,

Amrou

Reply 1

Renaissance_boy

And here is one other very problematic question.

2,2-dimethylpentane can be formed by the catalytic hydrogenation of either of two alkenes. Draw these two alkenes and label the one that shows stereo isomerism.

How would I go about doing this?

Any help would be greatly appreciated!

Thank you very, very much!

Amrou

Reply 2

Eau

First question
H2SO4 acts as the electrophile. http://www.chemguide.co.uk/mechanisms/eladd/symh2so4.html#top

Second question
Draw the product 2,2-dimethylpentane out first. Then deduce which alkenes could produce this. I am guessing that the alkene group is going to be position 1- or 2-

Reply 3

Renaissance_boy

Thank you very much! That has explained alot.

There is just one other problem that is really puzzling me.

There is a question asking: Show by an equation how one mole of ethanol reacts with one mole epoxyethane.

I got the answer ethan -1, 2 diol.

The enxt question is aking how this reacts with one mole of epoxyethane. I litteraly have no clue what to do here!

And then the next part of the question is even more complicated.

It says:

Nonylphenol, HO-C6H4-C9H19, reacts with epoxyethan to form compunds which are used as non-ionic detergents. Write an equation for the reaction between one mole of nonylphenol and three mole of epoxyethane.

I really do not know what to do here!

Any help would be GREATLY appreciated!

Anyway, thank you SO much for all your help!

Amrou

Reply 4

Eau

First part first:

http://www.chemguide.co.uk/organicprops/alkenes/epoxyethane.html

Reply 5

Eau

Second part:

http://www.chemicalland21.com/specialtychem/perchem/NONYLPHENOL%20ETHOXYLATE.htm

Replace n with 3?

Reply 6

Renaissance_boy

Thank you SO much for your help! Amrou

No problem. :smile:

Hello...back again! This is just one tiny small question.

The question asks: Outline a mechanism for the addition of H-Br to 2-ethyl but-1-ene (which I have done), and explain why only one major product is obtained.

Why is only one major product obtained? Is it because there are no more atoms spare????

Thank you very much!

Amrou

Reply 9

charco

Study Forum Helper

There are two possible products when HBr is added to an asymmetric alkene such as propene.

Look up Markovnikov addition to alkenes
or addition to asymmetric alkenes

Incidentally 2-ethyl but-1-ene CH2=C(C2H5)2 is also asymmetric. The H atom tends to add to the CH2 side of the double bond, this is the major product...
CH3-CBr(C2H5)2

The explanation lies in the stability of the intermediate carbonium ion that is formed in each case. If the H atom adds to the CH2 group first then the C+ ion that is formed is tertiary and stabilised by +I effects from three alkyl groups. Were it to add to the other carbon then a 1º carbonium ion would be formed that is less stable.

The activation energy required to form the 3º c+ ion is consequently less and the rate is faster. This then produces the major product.