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DEPARTMENT OF CHEMISTRY

USE of transition metal Complexes in c-c coupling reactions.ByMr TB. Shabangu

What is coupling in chemistry?

It must be getting a girlfriend in chemistry.(http://images.clipartpanda.com/mean-king-cartoon-WorriedBoy.jpg ...30/09/2015)

COUPLING.The interaction of two physical systems with one another.. Occurs in the presence of a metal catalyst (eg palladium).

(http://www.iclipart.com/download.php?iid=267264&tl=clipart&safe=1&desktop=&adv= 30/09/2015)Eish!!!..My bad.

HOMO COUPLING.CROSS COUPLING.

Ph-Ph COUPLING

PhCH=CH2 PhBr and Vinyl chlorideEXAMPLES

EXAMPLES

HOMOCOUPLINGCouples two identical partners.

http://onlinelibrary.wiley.com/doi/10.1002/anie.201000576/abstract ..30/09/2015Example

cross couplingCoupling of two carbon atoms of different molecules.Occurs in the presence of a metal catalysts mostly palladium.

https://www.thieme.de/en/thieme-chemistry/sos-cross-coupling-and-heck-type-reactions-55592.htm ..accessed on30/09/2015Suzuki, Negishi and the Heck reaction are cross coupling.

C-C COUPLINGBonding of two compounds through carbon atoms. Occurs in the presence of a metal catalyst (eg palladium).Yields very weak signals at natural abundance.Its spectra appear larger for 13C enriched samples.

http://1.bp.blogspot.com/-GAK0eeIlyyg/UC6PMzM7LnI/AAAAAAAAA9o/ug_eQneqHOk/s400/jres1.jpg .30/09/15Spectra

CATALYSTSTransition metals make good catalysts for C-C coupling.Palladium is the most popular catalyst.Nickel and copper are also used in some reactions..The most common is tetrakis(triphenylphosphine)palladium(0)

(http://organicreactions.org/index.php/Cross-coupling_reactions_of_organotrifluoroborates ..30/09/2015)Example

.ROLE OF TRANSITION METALS IN C-C COUPLING.They act as catalysts.Mostly palladium is used.Nickel and copper are used wildely too.

http://phys.org/news/2014-05-kabuto-like-nickel-catalyst-bioactive-frameworks.html .. Accessed 30/09/2015

Nickel as a catalyst.

PALLADIUM BASED C-C COUPLING REACTIONS.

Pd hand holds the two carbons to the reaction.Only carbon bonded to certain atoms bonds to Pd.(http://icanhasscience.com/chemistry/nobel-prize-for-palladium/ ..accessed on 30/09/2015)The suzuki, Negishi and Heck reaction can be explained using the following reaction.

NEGISHI REACTION

USES OF COUPLING REACTIONS To make pharmaceuticals.To make agrochemicalsNatural products.In organic materials.

http://www.jst.go.jp/act-c/en/research_area/ongoing/hirano_en.html ..accessed on 30/09/2015pharmaceuticals

OXIDATIVE C-C COUPLING.

AGROCHEMICALS

http://www.slideshare.net/ashokjntu/suzuki-lectureslides-1 ..accessed on 30/09/2015Suzuki Reaction

(http://www.clipartof.com/portfolio/toonaday/illustration/confused-businesswoman-questioning-1050535.html... 30/09/2015)I smell some favoritism here.Whats so special about Pd?

low sensitivity of organopalladium compounds to water and air.Pd catalyzed reactions have a functional group tolerance. ABOUT PALLADIUM COMPLEXES.Presence of a zerovalent complex with two vacant sites.

OTHER COUPLING REACTIONSNameHybridizationCatalysttypeHeckspPd or NiCrossNegishisp or spPd or NiCrossSuzukisp or spPd or NiCrossHiyamasp or spPdCrossGlasserspCuHomoCastro-stephensspCuCrossUllmannspCuHomo

THE END!!THANK YOU.THANK YOU......THANK YOU.