Organic synthetical Reagents / Organic conversions

ORGANIC SYNTHATICAL REAGENTS
In organic chemistry tere are 9 functional groups namely carboxylic acids, alcohols, amines, carbonyl compounds, esters, amides, nitro compounds, carbohydrates and hydrocompounds. out of these 9 functional groups carboxylic acids ,alcohols are acids, amines only bases the remaining are neutral functional groups.
The compounds which are occiuring stability by the loss of a proton h+ followed by participated in resonance and get stability are called as acids ex carboxylic acids,alcohols.
the compounds which are occuring stability by donating a lone pair of electrons followed by participated in resonance and get stability are called as bases.ex amins only are the bases
the compounds which are occuring stability with out any loss of protons or electron pairs and participated in intra resonance are called as neutral functional groips.
ex nitrocompounds,esters,amides,carbonyl compounds,carbohydrates,hydrocarbons. the remaining functional groups are by functional groups like nitriles
all of the above functional groups nitro compounds,amides,esters,nitriles,carbonyl compounds are electron withdrawing groups,
acids,alcohols and amines are electron releasing groups.
in organic synthesis what ever it happen the only thing is one functional group is converted into another functional group i.e carbonyl functional group to alcohols,alcohols to carbonyl compounds,alcohols to acids,carbonyl compounds to hydrocarbons,olefins to epoxides,acids to esters etc…by functional interconversion functional group addition ,functional elimination through oxidation,reduction,carbon-carbon single bond formation,carbon n=carbon double bond formation (by organo maetalic reagents),rearrangements and coupling reactions.
todo functionalgroup interconversion,functional addition,functional elimination we are using some reagents either laborotically prepared or non-laborotyically prepared ,the reagents which are laboratory prepared are called as synthetical reagents.
in a reaction if one functional group is converted in to another functional group than it is said to be functional group interconversion
ex
in a reaction if one functional group is added in the product compared to reactant than it is said to be functional group addition reactions
ex
in a reaction if functional group is eliminated from the reactants than they are said to be functional group elimination reactions
ex
in some reactions the new carbon carbonn c-c single or carbon -carbon c=c double bond formation takes place.
ex
oxidations
reactions taking place with addition or gain of oxygens or removal of hydrogens are called as oxidationn reactions the reagents used for oxidations are called as oxidising reagents
oxidising reagents are electron difficient species meaning of that central atom in oxidising agent are in high oxidation state and having less no of electrons .
reductions
reactions taking place with addition or gain of hydrogens or removal of oxygens are called as reduction reactions.the reagents used for reductions are called as redusing reagents.
redicing reagents are electron excess or electron rich or electron densed species meaning of that central atom in reducing agents are in low oxidation state and having more no of electrons.
ex
redox reactions
in those reactions in which both oxidation and reduction takes place are called as redox reactions
Quinones
Quinones are generally used for dehydrogenation (Removal of hydrogen -dehydrogenation / Oxidation) and are reduced to corresponding hydroquinone.
Two important Quinones are often used for this purpose following are
1) 2,3-Dichloro-5,6-Dicyano-1, 4-benzoquinone (DDQ).
2) 2,3,5,6 Tetra chloro- 1, 4-benzoquinone (Chloranil).

BENZO QINONE DDQ CLORONILL
(DDQ)
• DDQ is a browning colour solid.
• It is very convenient to handle (non toxic).
• In DDQ there is a presence of four electron with drawing groups like two cyanide groups at 5,6 positions and two chlorine groups at 2,3 positions so all of these electron withdrawing groups are ready to pull ring electrons towards them so the ring of DDQ is electron deficient and it can act as electrophile (E + ,so it can ready to take electron excess species nucleophile nu –
• DDQ is very reactive and may be used in cases where the substrate is difficult to dehydrogenate.
• DDQ is used under anhydrous conditions because it decomposes in presence of water .
• Solubility DDQ mainly soluble in inert solvents. Like aromatic hydro carbons – benzene, xylene, toulene,chloro benzene, aliphatic halo compounds, ethers:- di ethyl ether, dioxane, Tetra Hydro Furan (THF). Alcohols:- ethyl alcohol, Methyl alcohol.
• solution of DDQ in benzene is red in color due to the formation of charge transfer complex, and after dehydrogenation DDQ is reduced to hydroquinone which is in yellow color solid and insoluble in benzene.
• IR data of DDQ is as follows, for conjugated carbonyl compounds 1674 cm-1 ,for olefins 1580 cm-1, and for cyanide group 2240 cm-1.

Applications of DDQ

• Aromatization / De hydrogenation.
• Oxidative cyclisation
• Preparation of salts of stabled aromatic cations
• steroidal chemistry
• Oxidation of phenols
• Oxidative dimerisation
• Oxidation of allylic, benzylic groups
• Isomerisation during dehydrogenation.