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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: 8039 on June 06, 2010, 04:01:40 am

Title: Shortest reaction pathway?
Post by: 8039 on June 06, 2010, 04:01:40 am

To make propyl methanoate from propane and methane in the shortest reaction pathway, I used this process:

1. propene -(h2o)-> propa-1-ol
2. methane -(cl2)-> chlorometane-(NaOh)-> methanol -(cr207/h+)-> methanoic acid
3. propanol + methanoic acid -(h2so4)->propyl methanoate

Is this a valid method?

And why is it wrong to make butan-1-ol with butene and h2o, why use butane to chlorobutane instead? my guess is unwanted reactions but I'm not sure...

and also, ethanol to ethanoic acid is a oxidation reaction I beleive, why is it dscribed as substitution in my book?

Title: Re: Shortest reaction pathway?
Post by: Souljette_93 on June 06, 2010, 09:47:24 am

Quote from: 8039 on June 06, 2010, 04:01:40 am

1. propene -(h2o)-> propa-1-ol
2. methene -(h2o)-> methanol -(cr207/h+)-> methanoic acid
3. propanol + methanoic acid -(h2so4)->propyl methanoate

Is this a valid method?

Cute, But there is no such thing as 'Methene'

Quote

And why is it wrong to make butan-1-ol with butene and h2o, why use butane to chlorobutane instead? my guess is unwanted reactions but I'm not sure...

and also, ethanol to ethanoic acid is a oxidation reaction I beleive, why is it dscribed as substitution in my book?

there's Nothing wrong with making Butene with water, but if given in the Question 'Butane' then you can't use water.
Which Text Book do you have? I've always known it to be Oxidⁿ


Souljette

Title: Re: Shortest reaction pathway?
Post by: chansthename on June 06, 2010, 10:41:56 am

remember that when you are using water and a chloroalkane, the process has a very low yield.
Chloroalkane_g + H2O_l ->alkanol_aq +HCl_aq
an alkene with water has a two way arrow and H3PO4 catalyst.

I prefer to just remember to do the following

Alkane_g + Cl2_g ->(UV light) chloroalkane_g + HCl_g
Chloroalkane_g + NaOH_aq -> alkanol_aq + NaCl_aq
alkanol_aq ->(Cr2O7 2-_aq /H+_aq) -> alkanoic acid_aq


also
Alkene_g + H2O_g <->(H3PO4/catalyst/300 degrees) alkanol_aq

chloroalkane_g + NH3+_g ->(alumina/400 degrees) alkanamine(?)_g + HCl_g

BTW, I have never really gotten the amine thing

for example is it supposed to be ethanamine or ethamine?

Title: Re: Shortest reaction pathway?
Post by: Martoman on June 06, 2010, 10:57:54 am

You replace the last letter with amine as in the former case.

Title: Re: Shortest reaction pathway?
Post by: kate26 on June 06, 2010, 11:02:53 am

with amine it depends on whether you are looking at the hydrocarbon with an amine group atttched or a amine group with a hydrocarbon attached.

i.e having a ethane molecule with an amine group gives you - aminoethane

but having a amine group with an ethyl group attached gives you ethylamine

its the same thing but just different ways of looking at it. either way on an exam would be fine

hope that helps

Title: Re: Shortest reaction pathway?
Post by: chansthename on June 06, 2010, 11:12:18 am

cheers martoman and kate

Quote from: kate26 on June 06, 2010, 11:02:53 am

i.e having a ethane molecule with an amine group gives you - aminoethane

but having a amine group with an ethyl group attached gives you ethylamine

not sure what the difference is, with ethane the amine will always be part of the longest chain.

what I have been told is to always use something amine, unless there is a higher ranking group (such as carboxyl)

Title: Re: Shortest reaction pathway?
Post by: kate26 on June 06, 2010, 11:18:27 am

there isnt really a difference. just some stupid person realised it can go either way.

and going with something amine will work. just chuck amino out the front if there is a carboxyl, like what you said :)