Edexcel Chemistry A2 Unit 5 ~ Wednesday 19th June 2013 (Now Closed)

The Hydroxides make it a darker green...

...opposed to [Cr(H2O)6]2+ which is also green?

I read somewhere on the internet it was a grey precipitate though I've also read it's dark green !

Omg that looks so hard, I'm worried now !

Is there a previous part to the question... isn't it the phenylamine ?

If not, I was going to say Tin Hydroxide... but realized that's not an organic compound

*


see underlined stuff and bold stuff

Does anyone know the reagents and conditions required to change phenylethanol to benzoic acid ?

Thanks - really struggling w / this stuff

Does anyone know the reagents and conditions required to change phenylethanol to benzoic acid ?

Thanks - really struggling w / this stuff

Heating with acidified potassium dichromate under reflux I think, it's from unit 4 for how carboxylic acid is prepared. Is that an exam question?

Is there a reason why amines lose a hydrogen atom when reacting with acyl halides to form N-substituted amines whilst when amines react with halogenoalkanes they keep their alkyl group and two hydrogens?

Hope that question made sense haha.

The only reactions for phenol we need to learn are with bromine water and nitration right? And the fact that the oh group makes the phenol more reactive than both methyl and benzene?

I'm currently typing up some notes for the amino acids section whilst comparing the book to the syllabus (headache).

Is anyone else making a point of remembering/using examples such as poly(lactic acid) despite the fact they are not included as 'needed' in the syllabus which instead lists: "condensation polymerization for the formation of polyesters such as terylene and polyamides such as nylon and Kevlar" as required?

Opinions!

Is there anyone willing to help on some complex questions?

Heating with acidified potassium dichromate under reflux I think, it's from unit 4 for how carboxylic acid is prepared. Is that an exam question?

Erm I believe an extra carbon is needed and the formula is C6H5COOH

I was thinking maybe CN- ions replacing the OH- to form H20 (or KOH for that matter)

using Unit 4 nitrile synthesis knowledge we can hydrolyze the C6H5CN as so:

C6H5CN + 2H20 + H+ ------> CH6H5COOH + NH4+

What do you guys think ?? yeah that reaction is correct, i always forget it --- its correct for your particular senario but i read the q wrong as usual




I see what you mean

True... there seems to be only one product, however if there is excess amine then it would react with the ammonium halide (product) in a reversible reaction to basically lose that hydrogen your talking about along with for example the Br- . Giving you 2 products... one you expected (with the NH group) & also a second product being made...

sorry I don't know what it's called when the amine gets a hydrogen and a halide but here's an example :

CH3CH2NH4Br


Hope that helps

Explain the following, including the appropriate equations in your answer:

i) Solid benzenediazonium chloride, C₆H₅--N⁺=NCL^-(not has to be triple rather than double), is not usually isolated because it is explosive.

ii) Stable solutions of diazonium ions cannot be obtained from aliphatic primary amines like propylamine.

I've only made a note of the use of polyamides in Nylon in Kevlar due to the alignments of polymer chains and strong hydrogen bonding.

I haven't actually come across poly(lactic acid) and made no note of it ! And all the DNA stuff I skipped for that matter Although I think that has nothing to do with polymerization.

WOAHHH are these exam question- i have absolutely no clue - all my easter holiday revision hasnt paid off

Explain the following, including the appropriate equations in your answer:

i) Solid benzenediazonium chloride, C₆H₅--N⁺=NCL^-(not has to be triple rather than double), is not usually isolated because it is explosive.

ii) Stable solutions of diazonium ions cannot be obtained from aliphatic primary amines like propylamine.