Reactions and properties of organic compounds

[chemkid_23]

Hi all,
We have a SAC on Monday (the write up of last week's prac) based on organic compounds.
I missed it and am completely lost of what happens in these reactions. ie balanced equation, structural, etc

cyclohexane + water =>   
cyclohexene + water => 

cyclohexane + bromine in hexane =>
cyclohexene + bromine in hexane =>

2-chloro-2-methylpropane + water =>

2-chloro-2-methylpropane + ethanol + solid potassium hydroxide =>    (we then had to test for the presence of Cl- ions in the mixture by acidifying it with 2M nitric acid)

ethanol + de-ionised water =>

glacial ethanoic (acidic) acid + ethanol + concentrated sulfuric acid =>   (it's then poured into a beaker of cold water)

ethanol + 1M sulfuric acid + potassium dichromate =>

glacial ethanoic acid + water =>
(we then added sodium hydrogen carbonate to this)

Help will be much appreciated.
Thanks

[Mao]

You should know that:

aliphatic hydrocarbons do not react much (unless in thermal splitting or catalytic splitting)

unsaturated hydrocarbons undergo addition reaction.

Halogen groups can be substituted by hydroxides.

Hydroxyl groups can be oxidized to carboxyl groups in presence of oxidants (such as permanganate and dichromate).

carboxylic acids react with alkanols in strong acidic conditions to form esters

ethanoic acid + sodium hydrogen carbonate is a simple acid/base reaction.

Not all of the reactions above will give an actual reaction. (some of the pairs don't do anything)

[PlayerKay]

This is pretty much exactly the same prac I did. Ill just write up my results here.
Cyclohexane + Water
Observation: Not miscible in water. Does not dissolve. Separates into 2 layers.
Explanation: Water is polar and cyclohexane is non polar, therefore insoluble.

Cyclohexene + Water
Observation: Same as above
Explanation: Same as above

Cyclohexane + Br2
Observation: Yellow colour became pale very slowly.
Explanation: The cyclohexane undergoes substitution reaction to produce a Bromocyclohexane + HBr

Cyclohexene + Br2
Observation: Yellow colour is decolourised
Explanation: The cyclohexene undergoes an addition reaction to produce 1,2 dibromo cyclohexane

2-chloro-2-methylpropane + water
Observation: Insoluble
Explanation: Even though 2-chloro-2-methylpropane contains a chloro functional group, the molecule is overall non polar.

2-chloro-2-methylpropane + ethanol + solid potassium hydroxide
Explanation: 2-chloro-2-methylpropane is soluble in ethanol
2-chloro-2-methylpropane + OH-(provided from KOH) undergoes substitution to produce 2-methylpropan-2-ol + Cl-
HNO3 is added to neutralise the excess KOH
AgNO3 is added to precipitate the chloride ions. Cl- + AgNO3 --> AgCl + NO3-

Ethanol + De-ionised water
Observation: Soluble
Explanation: Water and Ethanol are both polar. Hydrogen bonds are formed between water and ethanol. There was little to no effect on the litmus paper, indicating that the solution is neither acidic nor basic.

The rest of our prac is slightly different to yours but I'll try to provide as much help as possible
glacial ethanoic (acidic) acid + ethanol + concentrated sulfuric acid
This is an example of an esterification. It will produce Ethyl Ethanoate. The sulfuric acid is a dehydrating agent which allows the condensation reaction to proceed. It will have a distinctive smell. It will also not dissolve in water since it is non polar.

[chemkid_23]

LOL
Thanks for the detailed help guys. I'll go over it thoroughly today and try to
understand as much as I can. Thanks again.

[Lols123]

"Cyclohexane + Br2
Observation: Yellow colour became pale very slowly.
Explanation: The cyclohexane undergoes substitution reaction to produce a Bromocyclohexane + HBr "

Don't alkanes not react with Bromine usually? :S

[ariawuu]

"Cyclohexane + Br2
Observation: Yellow colour became pale very slowly.
Explanation: The cyclohexane undergoes substitution reaction to produce a Bromocyclohexane + HBr "

Don't alkanes not react with Bromine usually? :S

In UV light.. they can

[Vincezor]

Don't alkanes not react with Bromine usually? :S

Might I add that the reaction is not almost instant as it sis with Cyclohexene + Br2, so it'll reactly slowly in the presence of sunlight (UV light)

[Lols123]

anyone got any ideas on this one: glacial ethanoic acid + water =>
:/

[Vincezor]

Both glacial ethanoic acid and water are polar. Therefore they form hydrogen bonds between ethanoic acid and water. Therefore it is soluble.

Also, the reason why there is the double arrow is because ethanoic acid is a weak acid, so the reaction could go both ways...

The solution is acidic, so it will turn blue litmus red.



EDIT: Glaicial Ethanoic acid is infact in liquid state, not aqueous as I previously wrote.
EDIT 2: Accidentally wrote the wrong reaction for when glacial ethanoic acid is added to water, sorry!

[Lols123]

oh okay

2-chloro-2-methylpropane + ethanol + solid potassium hydroxide
Explanation: 2-chloro-2-methylpropane is soluble in ethanol
2-chloro-2-methylpropane + OH-(provided from KOH) undergoes substitution to produce 2-methylpropan-2-ol + Cl-
HNO3 is added to neutralise the excess KOH
AgNO3 is added to precipitate the chloride ions. Cl- + AgNO3 --> AgCl + NO3-

and with this one. is there any reason why you might get a brown precipitate instead of a white one for AgCl..
or have i made an error

[vea]

Both glacial ethanoic acid and water are polar. Therefore they form hydrogen bonds between ethanoic acid and water. Therefore it is soluble.

Also, the reason why there is the double arrow is because ethanoic acid is a weak acid, so the reaction could go both ways...

The solution is acidic, so it will turn blue litmus red.

hai vince

just want to add that glacial ethanoic acid is pure ethanoic acid so it is (l) not (aq).

[Vincezor]

hai vince

just want to add that glacial ethanoic acid is pure ethanoic acid so it is (l) not (aq).

mmm thanks for the the correction , I'll edit it now.

[Mao]

@vince, I think you forgot to add NaHCO3 to the left hand side.

[Vincezor]

@vince, I think you forgot to add NaHCO3 to the left hand side.

Oh! just realised :S In fact, I believe I somehow 'merged' too adjacent reactions together, I'll fix it now :S

My bad!

[PsychoT]

Hate to bring up something this old, but has anyone else done this prac?

Is there any other info on each reaction or the properties of each organic compound I should know of? Think i've got most of it covered, thought i'd check. Got my SAC on this prac, spose you can never be too careful.

Cheers.