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    Which one is the most interesting?

    1) Grignard reagent preparation of benzoic acid from bromobenzene.
    2) Friedel Grafts Acylation preparation of bromobenzophenone.
    3) Hoffman degradation preparation of methylamide from ethanamide.
    4) Preparation of an ester - the characteristic flavour of pineapples.
    5) Isolation of caffeine from tea.
    6) Isolation of either oil of cloves or oil of lavender.

    I don't know what any of them are, but if any A2 students/uni people could tell me, I'd appreciate it. This is a chemistry assignment for UCAS/personal statement and will last a whole day so it is important.
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    (Original post by Widowmaker)
    Which one is the most interesting?

    1) Grignard reagent preparation of benzoic acid from bromobenzene.
    2) Friedel Grafts (Friedel Crafts) Acylation preparation of bromobenzophenone.
    3) Hoffman degradation preparation of methylamide (methylamine) from ethanamide.
    4) Preparation of an ester - the characteristic flavour of pineapples.
    5) Isolation of caffeine from tea.
    6) Isolation of either oil of cloves or oil of lavender.

    I don't know what any of them are, but if any A2 students/uni people could tell me, I'd appreciate it. This is a chemistry assignment for UCAS/personal statement and will last a whole day so it is important.

    What do you mean by most interesting?
    What they all are? Specific organic chemistry procedures (all well documented) to either prepare or extract a specific compound.

    Preparation by:
    A. Reaction, extraction, purification, determination (1,2,3 and 4)
    or
    B. Extraction, purification and determination (5 and 6)

    Personally, I like Grignard syntheses for the difficulty and danger aspects, but extraction of plant derivatives also has its merits. :rolleyes:
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    I' can only relate to questions 1,2 and 4....and I would say Q4 looks relatively simple and most likely the most enjoyable.
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    i agree question 4 seems to be the most interesting
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    (Original post by Vishpatel)
    i agree question 4 seems to be the most interesting
    that's good cos I chose it!
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    i did ester practical before... i dunno how it 'sounds interesting'

    bascially it envolves adding alcohols like methanol, ethanol and propanol...etc. to carboxhylic acids like methanoic acid, ethanoic acid... etc and you get esters. Very simple experiment so maybe it was the best to do but trust me it's not interesting - the theory behind it is p*** and it's just a mixing exercise.

    Saying that, it's does envolve a lot of sniffing solvents so it's all well and good. You'll find that the esters smell nothing like they are supposed to smell so you'd smell something that supposingly smells of strawberries that actually smells of toilet cleaner and pineapple would actually smell of nail varnish remover.

    bromobenzophenone... wtf is that? (good question for charco to answer) I think 2 is interesting...!!!
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    (Original post by Revenged)
    i did ester practical before... i dunno how it 'sounds interesting'

    bascially it envolves adding alcohols like methanol, ethanol and propanol...etc. to carboxhylic acids like methanoic acid, ethanoic acid... etc and you get esters. Very simple experiment so maybe it was the best to do but trust me it's not interesting - the theory behind it is p*** and it's just a mixing exercise.

    Saying that, it's does envolve a lot of sniffing solvents so it's all well and good. You'll find that the esters smell nothing like they are supposed to smell so you'd smell something that supposingly smells of strawberries that actually smells of toilet cleaner and pineapple would actually smell of nail varnish remover.

    bromobenzophenone... wtf is that? (good question for charco to answer) I think 2 is interesting...!!!
    why me? :confused:

    OK I'll have a go...

    acylation is addition of C6H5CO- to something.

    If you're adding this group to a benzene ring then use of a halogen carrier (Friedel Crafts) catalyst such as AlCl3 is recommended...

    C6H5COCl + AlCl3 --> C6H5CO+ + AlCl4- (not strictly speaking true but it serves)

    C6H5CO+ + C6H5Br --> BrC6H4-CO-C6H5 [electrophilic substitution]

    That's my guess ... any others?

    Incidently I concur with rev - esters never smell like they're supposed to.

    Ethanol + ethanoic acid ..... smells like vinegar
    methanol + ethanoic acid .... smells like vinegar
    ethanol + propanoic acid .. smells like vinegar
    propanol + propanoic acid .. smells like vinegar

    and the famous one..

    methanol + salicylic acid...
    oh yes beautiful smell of... vinegar (bah, oil of wintergreen my arse, oil of chip shop more like)
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    You say this is for a whole day - if you plan on doing (4) you will have too much time, making most simple esters is just a matter of whacking the two chemicals in together and Bob's your uncle. Did it, including the theory, in a 1 hour A-level class. Having said that, I didn't do any of the other reactions at A-level, wasn't until my degree that I did Grignard Reactions and Friedel Crafts Acylations.

    Marcus
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    lol, cuz you know everything about chemistr charco... and i dont remember all the esters smelling of vinegar but i think some of them are bound to
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    (Original post by Revenged)
    lol, cuz you know everything about chemistr charco... and i dont remember all the esters smelling of vinegar but i think some of them are bound to
    Obviously they will if you've added too much acid... Or perhaps if your starting alcohols are old, they may have been oxidised to the acid form themselves.

    Marcus
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    I tried to isolate caffiene from tea, it took a very long time and I don't think the white solid I ended up with was caffiene as it had the wrong melting point! Luckily it wasn't an assessed practicle!
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    Caffeine is an alkaloid, so will dissolve in dichloromethane, and you can use this to extract it from a tea/coffee/coca cola solution in water. Dry it in the usual way, then evaporate away the solvent. Then purify by recrystallisation in ethyl acetate.

    Regards your melting point, how did you do this? Caffeine sublimes before it melts.

    Marcus
 
 
 
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