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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Moneyking on November 08, 2012, 10:30:18 PM

Title: organic chemistry mixtures
Post by: Moneyking on November 08, 2012, 10:30:18 PM
Explain why it would be difficult to prepare methoxyethane by reacting a mixture of CH3OH and CH3CH2OH with H2SO4. What physical method can be used to prepare the required product?

I know that methoxyethane is C3H8O.
Title: Re: organic chemistry mixtures
Post by: orgopete on November 09, 2012, 12:20:30 AM
If you attempted the reaction, would you form dimethyl ether also?
Title: Re: organic chemistry mixtures
Post by: Borek on November 09, 2012, 03:49:58 AM
Try to list all possible products.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 09, 2012, 12:18:16 PM
Try to list all possible products.
How can i list the products? is there like an example or tutorial?
Title: Re: organic chemistry mixtures
Post by: Borek on November 09, 2012, 12:24:35 PM
How can i list the products? is there like an example or tutorial?

None required, all you need is just some logic.

Do you know anything about the reaction taking place? Anything about mechanism, or at least reaction equation? Can you draw structural formulas of all substances mentioned so far?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 09, 2012, 03:40:38 PM
How can i list the products? is there like an example or tutorial?

None required, all you need is just some logic.

Do you know anything about the reaction taking place? Anything about mechanism, or at least reaction equation? Can you draw structural formulas of all substances mentioned so far?
I can draw the structural formula:
CH3OH:
    H
    |
H-C-OH
    |
    H

C2H5OH:
    H  H
    |  |
H-C-C-OH
    |  |
    H  H

H2SO4:
      O
      ||
H-O-S-O-H
      ||
      O

WHAT DO I DO NEXT?
Title: Re: organic chemistry mixtures
Post by: Borek on November 09, 2012, 04:05:12 PM
Methoxyethane?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 09, 2012, 04:32:23 PM
Methoxyethane?
    H    H  H
    |     |  |
H-C-O-C-C-H
    |     |  |
    H    H  H
Title: Re: organic chemistry mixtures
Post by: Borek on November 09, 2012, 04:53:07 PM
Do you see how methoxyethane can be made from methanol and ethanol?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 09, 2012, 11:01:36 PM
Do you see how methoxyethane can be made from methanol and ethanol?
is that correct?
methanol+ethanol = methoxyethane + H2O
Title: Re: organic chemistry mixtures
Post by: orgopete on November 09, 2012, 11:48:52 PM
What would happen if you forgot to add ethanol?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 10, 2012, 02:19:58 PM
What would happen if you forgot to add ethanol?
umm nothing, no reaction would happen... it would still be methanol... right?
Title: Re: organic chemistry mixtures
Post by: orgopete on November 10, 2012, 04:30:03 PM
No, the product would be dimethyl ether, CH3OCH3. Do you understand now?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 12, 2012, 09:15:07 PM
No, the product would be dimethyl ether, CH3OCH3. Do you understand now?
how can methanol=dimethyl ether?
i think it should be ethanol=dimethyl ether
am i correct?
because
(ethanol)CH3CH2OH=CH3OCH3
(methanol)CH3OH=CH2OCH2
Title: Re: organic chemistry mixtures
Post by: orgopete on November 13, 2012, 03:08:11 AM
Dimethyl ether is the product of methanol plus mineral acid. This is because the oxygen is protonated and becomes a leaving group. The oxygen of another methanol will substitute the protonated oxygen to product water and dimethyl ether. You need to know that is how the reaction works. Therefore, if two different alcohols were used, you would get a mixture.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 08:13:00 AM
Dimethyl ether is the product of methanol plus mineral acid. This is because the oxygen is protonated and becomes a leaving group. The oxygen of another methanol will substitute the protonated oxygen to product water and dimethyl ether. You need to know that is how the reaction works. Therefore, if two different alcohols were used, you would get a mixture.
Ok so, sulfiric acid + methanol = dimethyl ether?
"Therefore, if two different alcohols were used, you would get a mixture."
what do you mean by that?
Title: Re: organic chemistry mixtures
Post by: Arkcon on November 13, 2012, 08:59:12 AM
So, pick two alcohols:  say methanol and ethanol, if you make ethers with sulfuric acid, what ethers do you suspect you'll get?  Do you expect just dimethyl ether and diethyl ether?
Title: Re: organic chemistry mixtures
Post by: Borek on November 13, 2012, 09:01:04 AM
Imagine you have a pocket full of black and white marbles. You take two at random. Do you expect to draw always two identical ones?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 12:03:02 PM
So, pick two alcohols:  say methanol and ethanol, if you make ethers with sulfuric acid, what ethers do you suspect you'll get?  Do you expect just dimethyl ether and diethyl ether?
you will get random, either dimethyl ether, or diethyl ether. is that correct?
Title: Re: organic chemistry mixtures
Post by: Borek on November 13, 2012, 12:14:19 PM
So you will never draw one white and one black?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 03:47:35 PM
So you will never draw one white and one black?
lol i was answering the other dudes question, and for yours, you won't always draw 2 black or 2 white, sometimes you will draw one white and one black.
say 10 balls, 5 black and 5 white, the % of getting 1 white and 1 black is greater than getting 2 blacks and 2 whites.
(1/2)*(4/9)0.44 for 2 blacks or 2 whites, and the other equation is (1/2)*(5/9)=0.55
getting 1 white and 1 black is slightly higher.
Title: Re: organic chemistry mixtures
Post by: Borek on November 13, 2012, 03:57:37 PM
you will get random, either dimethyl ether, or diethyl ether. is that correct?

and for yours, you won't always draw 2 black or 2 white, sometimes you will draw one white and one black.

And you still don't see what is the problem here?
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 04:21:08 PM
you will get random, either dimethyl ether, or diethyl ether. is that correct?

and for yours, you won't always draw 2 black or 2 white, sometimes you will draw one white and one black.

And you still don't see what is the problem here?
umm, i think the problem is we don't know the output?
Title: Re: organic chemistry mixtures
Post by: DrCMS on November 13, 2012, 04:55:59 PM
umm, i think the problem is we don't know the output?

No the problem is you have not listened for even one second to what people have been trying to tell you helpfully for the last 4 days. 

Start with mixture of alcohols and you will get a mixture of symmetrical and unsymmetrical ethers.

If you react methanol with sulphuric acid you get dimethyl ether and if you react ethanol with sulphuric acid you get diethyl ether.

But if you react a mixture of methanol and ethanol with sulphuric acid you get a mixture of dimethyl ether, diethyl ether and methoxyethane.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 05:38:51 PM
umm, i think the problem is we don't know the output?

No the problem is you have not listened for even one second to what people have been trying to tell you helpfully for the last 4 days. 

Start with mixture of alcohols and you will get a mixture of symmetrical and unsymmetrical ethers.

If you react methanol with sulphuric acid you get dimethyl ether and if you react ethanol with sulphuric acid you get diethyl ether.

But if you react a mixture of methanol and ethanol with sulphuric acid you get a mixture of dimethyl ether, diethyl ether and methoxyethane.
how do you get methoxyethane from that mixture?
Title: Re: organic chemistry mixtures
Post by: Arkcon on November 13, 2012, 05:47:33 PM

how do you get methoxyethane from that mixture?

One white ball and one black ball.  Like DrCMS: said, this has been an issue this entire thread: you keep saying you understand that you never know which two will end up coupled by an ether link, yet you consistently forget that you might get an ether with mixed groups.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 05:54:25 PM

how do you get methoxyethane from that mixture?

One white ball and one black ball.  Like DrCMS: said, this has been an issue this entire thread: you keep saying you understand that you never know which two will end up coupled by an ether link, yet you consistently forget that you might get an ether with mixed groups.
ok, so what you are saying is you can either get dimethyl ether, or diethyl ether or methoxyethane right? not all 3 of them in just one reaction?
Title: Re: organic chemistry mixtures
Post by: DrCMS on November 13, 2012, 06:03:45 PM

how do you get methoxyethane from that mixture?

One white ball and one black ball.  Like DrCMS: said, this has been an issue this entire thread: you keep saying you understand that you never know which two will end up coupled by an ether link, yet you consistently forget that you might get an ether with mixed groups.
ok, so what you are saying is you can either get dimethyl ether, or diethyl ether or methoxyethane right? not all 3 of them in just one reaction?

NO NO NO!!!

What every person trying to help you has been saying right from the start is that you will get a mixture of all three products.
Title: Re: organic chemistry mixtures
Post by: orgopete on November 13, 2012, 06:05:08 PM
Imagine you have a pocket full of black and white marbles. You take two at random. Do you expect to draw always two identical ones?

I rather liked this example. I wish I had thought of it. I thought it explained getting a mixture of products without telling the poster he would get a mixture of products.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 06:09:22 PM
Imagine you have a pocket full of black and white marbles. You take two at random. Do you expect to draw always two identical ones?

I rather liked this example. I wish I had thought of it. I thought it explained getting a mixture of products without telling the poster he would get a mixture of products.
how is that possible? where do the extra Carbons come from?
Title: Re: organic chemistry mixtures
Post by: DrCMS on November 13, 2012, 06:09:48 PM
Imagine you have a pocket full of black and white marbles. You take two at random. Do you expect to draw always two identical ones?

I rather liked this example. I wish I had thought of it. I thought it explained getting a mixture of products without telling the poster he would get a mixture of products.

Yeh but it seems even telling them the actual answer has not got the message across. 

I got sick of watching you all being helpful while Moneyking did not try to understand at all.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 06:14:14 PM
Imagine you have a pocket full of black and white marbles. You take two at random. Do you expect to draw always two identical ones?

I rather liked this example. I wish I had thought of it. I thought it explained getting a mixture of products without telling the poster he would get a mixture of products.

Yeh but it seems even telling them the actual answer has not got the message across. 

I got sick of watching you all being helpful while Moneyking did not try to understand at all.
I am trying to understand, but i just don't get it?!?
Title: Re: organic chemistry mixtures
Post by: Borek on November 13, 2012, 06:31:28 PM
Any two alcohol molecules can react producing ether.

If you have just one alcohol, every time two molecules react they are identical, so what is produced is a diX ether - be it diethyl or dimethyl (two white marbles when all marbles are white, or two black marbles when all marbles are black).

But if you have a mixture of both alcohols, two molecules that react can be either identical (two whites or two blacks) or two different (white and black), so there are three possible products.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 09:43:44 PM
Any two alcohol molecules can react producing ether.

If you have just one alcohol, every time two molecules react they are identical, so what is produced is a diX ether - be it diethyl or dimethyl (two white marbles when all marbles are white, or two black marbles when all marbles are black).

But if you have a mixture of both alcohols, two molecules that react can be either identical (two whites or two blacks) or two different (white and black), so there are three possible products.
k, so um can you just show me how ethanol + methanol + sufuric acid = methoxyethane + dimethy ether + diethyl ether?

what happens to the Sulphur? what about the Carbons, where do they come from?
Title: Re: organic chemistry mixtures
Post by: Arkcon on November 13, 2012, 10:27:41 PM

k, so um can you just show me how ethanol + methanol + sufuric acid = methoxyethane + dimethy ether + diethyl ether?

what happens to the Sulphur? what about the Carbons, where do they come from?

To answer those questions, you will have to start with a simpler question.  Consider: just methanol and sulfuric acid.  You know they form dimethyl ether.  Try to complete the reaction yourself, if you want to know where the sulfur goes.  Try to draw the structure of methanol and dimethyl ether, if you're having trouble keeping track of the carbons.
Title: Re: organic chemistry mixtures
Post by: Moneyking on November 13, 2012, 10:50:45 PM

k, so um can you just show me how ethanol + methanol + sufuric acid = methoxyethane + dimethy ether + diethyl ether?

what happens to the Sulphur? what about the Carbons, where do they come from?

To answer those questions, you will have to start with a simpler question.  Consider: just methanol and sulfuric acid.  You know they form dimethyl ether.  Try to complete the reaction yourself, if you want to know where the sulfur goes.  Try to draw the structure of methanol and dimethyl ether, if you're having trouble keeping track of the carbons.
dimethyl ether has 2 carbons, and methanol has only 1 carbon, where does the other carbon come from?!?
Title: Re: organic chemistry mixtures
Post by: Borek on November 14, 2012, 03:53:10 AM
dimethyl ether has 2 carbons, and methanol has only 1 carbon, where does the other carbon come from?!?

You have already shown you know how ethers are produced:

methanol+ethanol = methoxyethane + H2O

so you know answer to your question.

You are just trolling now.

Topic locked.