Haloform Reaction

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Preparation of Primary Amines Reaction Mechanism of LiAlH4 by Action from Amides ve Nitriles

LiAlH4 RCN RCH2 NH2

LiAlH4 R CONH2 RCH2 NH2

O RCH CH • LiAlH4 is converted to alcohols by reducing R‐CHO, R2C=O, R‐COOH, 2 RCOOR, RCOCl molecules.

LiAlH4 RCHO RCH2OH

Reduction of Carbonyl Derivatives Catalytic Reduction (Hydrogenolysis) with NaBH 4 Hydrogenolysis is called that is opened by hydrogen and a metal catalyser the bond in the ethylenic and acetylenic unsaturated structures and the NaBH4 is a weaker reduction agent than LiAlH4. It is used to reduce bond between carbon and heteroatom. These metals are platinum (Pt), aldehydes and ketones majorly. The reduction process with NaBH4 can be carried out in an aqueous medium or alcohol. rutenium (Ru), palladium (Pd) and nickel (Ni).

Examples of Reduction Haloform Reaction

using Metal / Acid System • The halogenation of the ‐C atom of many ketone compounds can be carried out in the form of total halogenation in a basic medium. So methyl ketones • It is used Zn, Fe, Sn / HCl, H2SO4 and SnCl2,FeSO4.Whenmetalistreated [CH3‐CO‐] contain three halogen atoms in ‐C and are formed trihalomethyl with acid, the hydrogen gas is formed on the rise. ketones.

Zn / HCl O Ar NO2 Ar NH2 base O R C CH + X R CO O - + CH X Zn- Hg 3 2 3 Ar C R Ar CH R HCl, heat 2 O • The haloform reaction takes place via the hypohalogenide derivative of Zn- Hg halogens in basic medium. RCH RCH3 conc. HCl, heat

• Zn also reduces in aqueous and alcoholic medium.

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Reaction Mechanism Haloform Reaction

• The trihalomethyl group of the resulting compound forms a leaving group • General Reaction Equation for the nucleophilic acyl substitution, resulting in the formation of the carboxylated aryl which is displaced by the basic OH‐ group of the O O O X2 , OH OH RCCH3 medium. However, the immediate rapid proton exchange completes the RCCX3 RCO + CHX3 (X=Cl , Br , I ) formation of the haloform derivative with the carboxylate anion. Methyl ketone 2 2 2 Carboxylate Haloform anion Trihalomethylketone ...... izole edilemez .O ..O.. ..O .. RCCX + .OH RCCX RC + . 3 .. 3 .CX3 • Example O O Ext. .OH .OH Br2 .. .. CH3 CH2 CCH3 CH3 CH2 CCBr3 nucleophilic acyl OH substitution OH

O O RCO + CHX3 CH3 CH2 CO + CHBr haloform 3 carboxylate Propionate anion Bromoform ion derivative

Haloform Reaction Example Haloform Reactions

• When halogen is I2, the haloform derivative (iodoform) is a solid compound which can be isolated in the form of a yellow precipitate. This reaction can also be used as a diagnostic reaction for methyl ketones with the so‐called “iodoform test”. However bromoform and chloroform are liquid and volatile. They can not be easily isolated from the reaction medium. O O O C CH3 Ext. I2 OH Ph C CI3 Ph C O + CHI3 OH Benzoate anion Iodoform

• Since I2 is an oxidant, a positive iodoform test with alcohols is observed. Because first, the alcohol is oxidized to methyl ketone, followed by the haloform reaction.

Benzilic Acid Synthesis General Reaction Equation

• Benzilic acid synthesis can be seen as a method of obtaining α‐hydroxy carboxylic acid. The benzilic acid is synthesized by the action of benzaldehyde.

• When the benzaldehyde molecule is boiled with KCN in alcoholic medium, the two molecule benzaldehyde gives the benzoin molecule as a condensed molecule.

• Benzil molecule with ‐diketone structure is formed by oxidation of benzoin. The benzilic acid salt is formed by the molecular rearrangement (conversion reaction) of this structure in the alkaline solution.

Copper(II)acetate

(-hydroxy ketone)