Alcohols Help

[3502]

Hey guys,

 

Really struggling with a section of questions on Alcohols, and would be extremely grateful for any assistance anyone may be able to give!

 

You are given two samples of alcohol 1-Butanol which reacts with acidified potassium dichromate K2Cr2O7/H+ under different conditions to produce two products.  

 

Describe the conditions required to produce the different products, giving the names and structural formulae of the products produced and equations to summarise the reactions involved

 

Name and state the structural formula of the product that would result from treating 2-Butanol with acidified potassium dichromate (K2Cr2O7/H+) and heating under reflux and using the same reagent, describe how to distinguish between alcohols 1-Butanol, 2-Butanol and 2-methly-2-propanol.

 

Esters can be synthesised in the reaction between alcohols and carboxylic acids in a reaction called esterification. 

 

Ethanol reacts with propanoic acid, name the product of the reaction with its structural formula.

 

[exchemist]

 

Hey guys,

 

Really struggling with a section of questions on Alcohols, and would be extremely grateful for any assistance anyone may be able to give!

 

You are given two samples of alcohol 1-Butanol which reacts with acidified potassium dichromate K2Cr2O7/H+ under different conditions to produce two products.  

 

Describe the conditions required to produce the different products, giving the names and structural formulae of the products produced and equations to summarise the reactions involved

 

Name and state the structural formula of the product that would result from treating 2-Butanol with acidified potassium dichromate (K2Cr2O7/H+) and heating under reflux and using the same reagent, describe how to distinguish between alcohols 1-Butanol, 2-Butanol and 2-methly-2-propanol.

 

Esters can be synthesised in the reaction between alcohols and carboxylic acids in a reaction called esterification. 

 

Ethanol reacts with propanoic acid, name the product of the reaction with its structural formula.

 

Looks like an assignment so I won't do it all for you, but I'm happy to try to help you learn, as far as my rusty organic chemistry allows :).

 

First of allK2Cr2O7 has Cr in the +6 oxidation state, which is a very high oxidation state. This makes it an oxidising agent.

 

What do you think are the possible products of oxidising alcohols? 

[3502]

Hey,

 

Thanks for the reply.

 

 

I know Primary Alcohols oxidise to Aldehydes, Secondary to Ketones, and Tertiary dont. 

 

 

Of the ones listed above, 1-Butanol is a Primary alcohol, 2-Butanol is secondary, and 2-methly-2-propanol, and is a  Tertiary alcohol, But from there I do not really know how to go about answering the questions.

[exchemist]

 

Hey,

 

Thanks for the reply.

 

 

I know Primary Alcohols oxidise to Aldehydes, Secondary to Ketones, and Tertiary dont. 

 

 

Of the ones listed above, 1-Butanol is a Primary alcohol, 2-Butanol is secondary, and 2-methly-2-propanol, and is a  Tertiary alcohol, But from there I do not really know how to go about answering the questions.

 

Yes but primary alcohols don't only oxidise to aldehydes, do they?

 

What happens if you oxidise them harder, or if you try to oxidise an aldehyde? 

[3502]

Initially they would oxidise to an aldehyde, then they would oxidise to Carboxylic Acid?

[exchemist]

Initially they would oxidise to an aldehyde, then they would oxidise to Carboxylic Acid?

Bingo!  So now you can answer the first bit, if you know, or can look up, the difference in conditions for mild and more severe oxidation by K2CrO7/H+. 

 

So far we've covered the response to primary and secondary alcohols to this oxidising agent.  What do you think would happen to a tertiary alcohol? You are going to need that in a moment.  

[3502]

Bingo!  So now you can answer the first bit, if you know, or can look up, the difference in conditions for mild and more severe oxidation by K2CrO7/H+. 

 

So far we've covered the response to primary and secondary alcohols to this oxidising agent.  What do you think would happen to a tertiary alcohol? You are going to need that in a moment.  

 

Thanks again for your help, I am struggling with the oxidation conditions for K2CrO7 - Cannot seem to find much guidance online unless I am wording my queries incorrectly!

 

From my understanding, tertiary alcohols cannot be oxidised without breaking the double carbon bond?

[exchemist]

Thanks again for your help, I am struggling with the oxidation conditions for K2CrO7 - Cannot seem to find much guidance online unless I am wording my queries incorrectly!

 

From my understanding, tertiary alcohols cannot be oxidised without breaking the double carbon bond?

Yup exactly. 

 

Re conditions, have you not been taught something about conditions for use of K2Cr2O7?  If not, you can see something about it here: https://www.chemguide.co.uk/organicprops/alcohols/oxidation.html

 

Are you OK now? I have to pop out for an hour or so but should be on line later if you still need help. 

[OceanBreeze]

I'm stranded in Key West at the moment and getting to be an expert on alcohols if you need any help.

[exchemist]

I'm stranded in Key West at the moment and getting to be an expert on alcohols if you need any help.

I sincerely hope not! Anything other than ethanol will kill you. 

 

But seriously, are you stuck because of Covid-19, the weather, or some other reason? 

[OceanBreeze]

I need to be careful what I say since NOAA haven't issued any public statement yet.

 

It is COVID-19. We need some official position on continuing sea trials, about the need to get the crew tested, that sort of thing.

 

Nothing serious and if I have to be stranded, I can think of far worse places.

[3502]

Thanks so much for your help, working through it and will probably drop another message shortly if I get stuck!

[3502]

I need to be careful what I say since NOAA haven't issued any public statement yet.

 

It is COVID-19. We need some official position on continuing sea trials, about the need to get the crew tested, that sort of thing.

 

Nothing serious and if I have to be stranded, I can think of far worse places.

 

Hope all is ok!

[exchemist]

Thanks so much for your help, working through it and will probably drop another message shortly if I get stuck!

Looking at this (I had forgotten a lot of it) it seems you use a reflux condenser if you want to drive the reaction for primary alcohols through to carboxylic acid, whereas  you distil the aldehyde off and condense it separately if you want to stop the oxidation at the first stage. 

 

I think the rest of it is pretty simple - just a question of reactions schemes, formulae and names. (I may not be a good guide on names, as I did this stuff 40 years ago and naming conventions have a habit of altering over time :) )