AS Chemistry P2 Prep.

[angelicsuccubus]

yeah....errr, that's what she asked the colour of the product of reaction between aldehydes/ketones and 2-4 DNPH

oh oh I misquoted! I meant to quote the post before you, sorry

 

[TahaJamshed]

can sumone tell me when we react phosphorous with oxygen when is it P205,P203 AND P406/P4010

depends if in excess oxygen then P4O10 whose emperical formula is P2O5 so its the same but if in limited oxygen than P406 whose emperical formula is P2O3 so the same again so two different compounds are made actually so its a mixture of phosphates but in our syllabus it would be better if you just use Phosphurus (V) valency and write P plus O2 gives P4O10 that is P2O5

 

[oldfashionedgirl]

oh oh I misquoted! I meant to quote the post before you, sorry

haha,its ok, no prob

 

[TahaJamshed]

Yeh it happens with Bromine too.. and I said earlier when I posted these, I'm sorry if I missed any so just fix the list. I didn't go through esters or carboxylics so I probably missed stuff from there.. and I thought aldehyde--> carboxylic was pretty obvious but oh well.. and I didn't have heat reflux for nucleophilic substitution with HBr in my notes, so..

Phosphorus can react with Cl I and Br to make PCl3 or PI3 or PBr3 respectively and they all react with alchols to give halagenoalkanes this is in responce to Jaf

 

[BazD]

"Heating under reflux means heating with a condenser placed vertically in the flask to prevent loss of volatile substances from the mixture"

Thats what it means. More or less, similar to distillation.

Dude, suppose you want an aldehyde, from the oxidation of a primary alcohol, the condition will be to use potassium dichromate solution and "distill" the rxn mixture. Not reflux, hence reflux is NOT similar to distillation, and it might not be the "exact" opposite but for a fact it prevents distillation so I presume you can't say they're the same....

 

[angelicsuccubus]

Dude, suppose you want an aldehyde, from the oxidation of a primary alcohol, the condition will be to use potassium dichromate solution and "distill" the rxn mixture. Not reflux, hence reflux is NOT similar to distillation, and it might not be the "exact" opposite but for a fact it prevents distillation so I presume you can't say they're the same....

trust me that girl got it, and now she's gone to sleep .. so no point in quoting now.

 

[BazD]

trust me that girl got it, and now she's gone to sleep .. so no point in quoting now.

Haha, I'm kinda new =P and don't really want people to not know basic stuff , right before the exam ... Oh well I have p5 tomorrow as well T_T

 

[kwazieeekezzy]

thanks...so u mean that i can show any functional group going out and into the paper etc??

yea

 

[angelicsuccubus]

Haha, I'm kinda new =P and don't really want people to not know basic stuff , right before the exam ... Oh well I have p5 tomorrow as well T_T

I just started looking at the p5 papers, wtf?! Im so lost! the markschemes are like uber-useless!

 

[kwazieeekezzy]

Haha, I'm kinda new =P and don't really want people to not know basic stuff , right before the exam ... Oh well I have p5 tomorrow as well T_T

errrm....apart 4rm alkenes what other hydrocarbon or carbonyl compounds can be polymerised??

 

[angelicsuccubus]

errrm....apart 4rm alkenes what other hydrocarbon or carbonyl compounds can be polymerised??

I haven't seen anything other than alkenes get polymerised

 

[kwazieeekezzy]

I haven't seen anything other than alkenes get polymerised

thanks

 

[kwazieeekezzy]

that means you're giving it heat by radiation or a bunsen burner or a reactor.. or anything.. but not refluxing it, and so if the condition is meant to be reflux, its important that you write reflux.

Organic chem reactions that use heat reflux:

1. Nucleophilic substitution of alcohols with a mixture of red phosphorus and Bromine/Iodine
2. Oxidation of primary alcohols to carboxylic acids
3. Oxidation of secondary alcohols to ketones
4. Nucleophilic substitution of halogenoalkanes with NaOH to form alcohols
5. Nucleophilic substitution of halogenoalkanes with KCN to form nitriles
6. Nitriles forming caboxylic acids using dil. HCl (Hydrolysis)

If I missed anything.. sorry

nucleophilic substition of halogenoalkanes with NaOH to alkenes

 

[TahaJamshed]

thanks

just remember alkenes with halogens attached to them give important polymers like chloroethene gives PVC so not just simple long chained or branched alkenes give polymers....

 

[mominzahid]

[G.Mod Edit. No discussion before 24 hours]

 

[kwazieeekezzy]

guys what will be formed when HOOCCH=CHCOOH is reacted with hot KMNO4?
please reply soon its urgent..

i guess a ketone will be formed

 

[Knight]

i guess a ketone will be formed

first a C=O bond is formed and then it's oxidation occurs and a carboxylic acid is formed

 

[MysteRyGiRl]

can ay1 plz explain da products formed when smthing is reacted with 2,4 DNPH?

 

[TahaJamshed]

can ay1 plz explain da products formed when smthing is reacted with 2,4 DNPH?

in case of aldehydes and ketones 2,4 DNPH reacts similar to the nucleophilic addition of HCN and gives a hydrogen to Oxygen in carbonyl group and than the whole rest of the molecule is joined to the carbon like addition of CN and than the OH and H on nitrogen which bonds with carbon of aldehyde or ketone form water so condensation occours and finally C forms double bond with N this organic compound is formed as ORANGE precipitate

 

[Knight]

can ay1 plz explain da products formed when smthing is reacted with 2,4 DNPH?