Anyone know how to start with this 😭

• Compound A, formula CH,OCl, reacts with cold water to form compound B, C3HsO2Cl. А solution of compound B turns blue litmus paper red.
• Compound A also reacts with cold ethanol to form a pleasant-smelling liquid, C, CsH,02Cl
• When compound B is heated under reflux with aqueous potassium hydroxide, a solid compound, D, can be isolated with formula C3H5O3
• Acidification of D produces compound E, C3H603, solutions of which also turn blue litmus paper red.
• Heating E under distillation with acidified potassium dichromate produces liquid F, C3H403. Compound F forms a silver mirror when warmed with Tollens' reagent.
Work out structures for the compounds A - F. Give some indication of your reasoning [6 marks)

Reply 1

TypicalNerd

18

Original post by planteater27

• Compound A, formula CH,OCl, reacts with cold water to form compound B, C3HsO2Cl. А solution of compound B turns blue litmus paper red.
• Compound A also reacts with cold ethanol to form a pleasant-smelling liquid, C, CsH,02Cl
• When compound B is heated under reflux with aqueous potassium hydroxide, a solid compound, D, can be isolated with formula C3H5O3
• Acidification of D produces compound E, C3H603, solutions of which also turn blue litmus paper red.
• Heating E under distillation with acidified potassium dichromate produces liquid F, C3H403. Compound F forms a silver mirror when warmed with Tollens' reagent.
Work out structures for the compounds A - F. Give some indication of your reasoning [6 marks)

I don’t think all the chemical formulae have parsed correctly. As such, it is difficult to give you reliable help beyond identifying possible functional groups.

A reacts with water to give an acidic solution (as indicated by the litmus hint) and with an alcohol to give an ester (as indicated by the pleasant smell hint). So A is either an acyl chloride or acid anhydride, B is a carboxylic acid and C is an ester.

B has a chlorine in it and appears to gain an oxygen atom (and maybe a hydrogen - again, the formulae as given in your post make that hard to tell) at the expense of a chlorine atom when reacted with KOH. This suggests a nucleophilic substitution, causing the chlorine to be replaced by a hydroxyl group. That said, since the reaction is carried out in base and because we know its precursor contained a carboxylic acid group, the product should really be the potassium salt of the hydroxy acid formed (KOH was used, hence why it should be a potassium salt). So this is almost certainly D.

E should be the conjugate acid of D as acidification of carboxylate salts gives the carboxylic acid.

Because E under distillation with acidified K2Cr2O7 yields an aldehyde (indicated by the silver mirror/Tollen’s test hint), we now know the hydroxyl group on E must be a 1° alcohol. This must mean that the chloroalkane position was also 1°. This is the crucial hint which tells us which isomers of all of our compounds are correct. We can now definitively say E is HO(CH2)2COOH and that F is HOOC(CH2)CHO.

Now working backwards:

D must be HO(CH2)2COOK / HO(CH2)2COO^-

C must be HO(CH2)2COOCH2CH3

B must be Cl(CH2)2COOH

A must be Cl(CH2)2COCl or (Cl(CH2)2CO)2O (depending on how the formula is supposed to read)

There are some things you can better justify (especially if this is a post-A level / equivalent question), but the above answer is what most qualifications equivalent to A level would expect.

(edited 2 months ago)

Reply 2

Pigster

20

Original post by planteater27

• Compound A, formula CH,OCl, reacts with cold water to form compound B, C3HsO2Cl. А solution of compound B turns blue litmus paper red.
• Compound A also reacts with cold ethanol to form a pleasant-smelling liquid, C, CsH,02Cl
• When compound B is heated under reflux with aqueous potassium hydroxide, a solid compound, D, can be isolated with formula C3H5O3
• Acidification of D produces compound E, C3H603, solutions of which also turn blue litmus paper red.
• Heating E under distillation with acidified potassium dichromate produces liquid F, C3H403. Compound F forms a silver mirror when warmed with Tollens' reagent.
Work out structures for the compounds A - F. Give some indication of your reasoning [6 marks)

Have you used OCR on a scanned image? Or has it been copy and pasted from a dodgy .pdf file?

Just re-read your Q and notice the gobbledegook some of your formulae are. I reckon I might be able to guess what some of the earlier formulae might have been, but it will be easier if you just correct them.

Hassium and caesium?

Reply 3

Imransheikh

It sounds like you're feeling a bit overwhelmed with starting something, and you're looking for guidance. If you could give me more details about what you're trying to begin—whether it’s an application, a personal statement, an essay, or another type of task—I can help you break it down and get started.
Feel free to share more, and I'll be happy to help you with a solid approach!

Anyone know how to start with this 😭

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