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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: lutesium on January 25, 2008, 07:59:36 PM

Title: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: lutesium on January 25, 2008, 07:59:36 PM
How can this reagent be synthesised? I can't find it anywhere so we have to synthesise it but how??? Would a reduction of acetophenone then bromination work?

Thanx


Lutesium...
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: sjh9 on January 25, 2008, 08:59:38 PM
Quote from: lutesium on January 25, 2008, 07:59:36 PM
How can this reagent be synthesised? I can't find it anywhere so we have to synthesise it but how??? Would a reduction of acetophenone then bromination work?

Thanx


Lutesium...

epoxidize styrene and ring open with br2
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: agrobert on January 25, 2008, 09:05:11 PM
Quote from: sjh9 on January 25, 2008, 08:59:38 PM
epoxidize styrene and ring open with br2

i like your style
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: lutesium on January 27, 2008, 06:26:41 AM
Me too I like your style :)

But can you give me some examples of epoxidation???

Thank you very very very much!


Lutesium...
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: sjb on January 27, 2008, 07:06:42 AM
Quote from: lutesium on January 27, 2008, 06:26:41 AM
Me too I like your style :)

But can you give me some examples of epoxidation???

Thank you very very very much!


Lutesium...

Racemic? Perhaps something like a peracid, or hydrogen peroxide.

Stereospecific? I think things like Sharpless epoxidation work OK for these substrates, or things like Shi's dioxirane chemistry...
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: Kryolith on January 27, 2008, 07:16:14 AM
Here you can find the epoxidation of styrene with a peracid:

http://www.organic-chemistry.org/namedreactions/prilezhaev-reaction.shtm

the treatment of bromohydrines with NaOH yields epoxides, as well.

Quote from: sjb on January 27, 2008, 07:06:42 AM
Stereospecific? I think things like Sharpless epoxidation work OK for these substrates, or things like Shi's dioxirane chemistry...

Jacobsen epoxidations of (Z)-olefines don't need allyl alcohols or functional groups.
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: lutesium on January 27, 2008, 07:35:50 AM
Wouldn't a ring opening wih HBr be better???
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: Kryolith on January 27, 2008, 07:45:33 AM
Quote from: sjh9 on January 25, 2008, 08:59:38 PM
epoxidize styrene and ring open with br2

Ring opening to which product?

Quote from: lutesium on January 27, 2008, 07:35:50 AM
Wouldn't a ring opening wih HBr be better???

Probably. But let's await sjh9's answer.
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: lutesium on January 27, 2008, 06:36:52 PM
Actually the desired product would be 2-Bromo-1-PhenylPropanol but Ethanol would suffice and I found a synthesis at one of the old sites! It uses N-BromoSuccinimide + H2O to build my block from styrene (propenylbenzene) and how can I attach an urea molecule to it??? By the aid of strong bases??? Please help me!!!


Lutesium...
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: Kryolith on January 27, 2008, 06:42:49 PM
So now you know how to synthesize 2-bromo-1-phenyl ethanol.  :)

Now you want to attach urea. To which carbon? Do you want to substitute bromide?
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: lutesium on January 27, 2008, 07:33:21 PM
Of course to the carbon where Br is located ;) 2nd carbon that means! Thank you very much for your interest Kyrolith!!!


Lutesium...
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: sjh9 on January 27, 2008, 09:52:08 PM
Quote from: Kryolith on January 27, 2008, 07:45:33 AM
Quote from: sjh9 on January 25, 2008, 08:59:38 PM
epoxidize styrene and ring open with br2

Ring opening to which product?

Quote from: lutesium on January 27, 2008, 07:35:50 AM
Wouldn't a ring opening wih HBr be better???

Probably. But let's await sjh9's answer.



It turns out that Styrene oxide is sold by aldrich. 

A quick search on sciencedirect.com for "epoxide halogenation" came up with this abstract:

The regioselective ring opening halogenation of some epoxides using elemental iodine and bromine in the presence of a series of pyridine-containing groups has been studied. The epoxides were subject to cleavage by elemental halogen (I2 and Br2) in the presence of isonicotinic hydrazide (isoniazide) under mild reaction conditions in various solvents. In this study, reagents and conditions have been discovered with which the individual halohydrins can be synthesized in high yield and with more than 95% regioselectivity.


Journal of Molecular Catalysis A: Chemical
Volume 215, Issues 1-2, 14 June 2004, Pages 55-62


Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: Kryolith on January 28, 2008, 03:47:02 AM
I've never heard of that before. Thanks you for the information.  :)
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: lutesium on January 30, 2008, 04:51:51 PM
Nobody knows how to attach the urea???


Lutesium...
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: Kryolith on January 31, 2008, 04:42:55 AM
A SN2 reaction in basic solution could work...
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: AWK on January 31, 2008, 06:12:11 AM
May be a reaction of styrene oxide with urea also will work.
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: adam on January 31, 2008, 10:51:53 AM
To run the epoxidation in a stereoespecific manner, I think Sharpless epoxidation doesn' t work well for styrene, to obtain high yield and good enantioselectivity an homoalillyc alcohol is needed for this kind of asymmetric epoxidation. 
A better option is to run a hydrolytic kinetic resolution of the terminal racemic epoxide catalyzed but chiral salen Co complexe, the yield must be less than 50% but the ee should be around 99%.
The styrene oxide is commercial available and "cheap".

Another way to obtain this compound in an enantioselective manner is performing the asymmetric reduction of the corresponding alfa bromo ketone, using a chiral boron reagent such as an oxazaborolidine developed by Corey.

Sorry for my poor english and the ortographically mistakes!!
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: thorium on January 31, 2008, 06:05:51 PM
How is an SN2 reaction made can someone explain it please,
Title: Re: Synthesis of 2-Bromo-1-PhenylEthanol
Post by: agrobert on January 31, 2008, 07:00:42 PM
Quote from: thorium on January 31, 2008, 06:05:51 PM
How is an SN2 reaction made can someone explain it please,

You should do a web search to learn about SN2 reactions.  Or try searching the forums.