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Cannizzaro reaction

Introduction

Synthesis

Application

Variants

Recent literature



Stanislao Cannizaro was an Italian

Chemist.

1826-1910 Cannizzaro reaction

The first to clearify the differencebetween Molecular and Atomic weights

In 1858 Cannizzaro published his "Sketchof a Course in Chemical Philosophy"in the journal Il Nuovo Cimento , in whichhe undertook to resolve many ofchemistry's outstanding issues, basing hisarguments on the work of Avogadro

Stanislao Cannizaro



Only works with aldehydes that are

non-enolisable, i.e. does not have anyα-protons.

In case of aldehydes that do have α-hydrogens, the aldol condensationreaction takes place preferentially.

Applicability



Aldehyde containing NO Alpha hydrogenundergo a Auto self-oxidation-reduction,

Disproportion, BasicHydrolysis,Nucleophilic addition reaction when

treated with conc. aqueous

base(NaoH/KoH) & it gives Acid and alcohol

Definition



Synthesis



Chemical reagents



Starting reagent

Aldehyde containing NO

Alpha hydrogen



Base

(NaoH/KoH)



Synthesis

One molecule of aldehyde is

reduced to the correspondingalcohol, while a second one isoxidized to the carboxylic acid.



The applicability of Cannizzaro reaction inorganic synthesis is limited as the yield isnot more than 50% for either acid or alcoholformed.

The α,α,α-Trihalo aldehyde undergo haloformreaction in strongly alkaline medium. E.g.Choral will give chloroform in presence of analkali.

Explanation



Explanation

Involves the bas-induced disproportionation of analdehyde lacking a hydrogen atom in the alpha

position.

The overall order of the reaction is usually 3 or 4.

The Cannizzaro reaction takes place very slowlywhen electron-donating groups are present. But thereaction occurs at faster rates when electron

withdrawing groups are present.



Mechanism



In case Dianion form



In Aromatic aldehyde



Argument ….

hydrogen is transferred from the second aldehyde

molecule is from the solvent.

* When the reaction is carried out with D 2 Oas solvent, the resulting alcohol does notshow carbon bonded deuterium. It indicatesthe hydrogen is transferred from thesecond aldehyde molecule, and not from thesolvent.



In case of aldehydes that do have α-hydrogens, the aldol

condensation reaction takes place preferentially.



The Biological Analogue of

the Cannizzaro Reaction



1) Formaldehyde is disproportionate to

Formic acid and Methyl alcohol instrong alkali.

ILLUSTR TIONS



Formic acid

It is used for decalcifier, reducer in dyeing forwool fast colures.

Grain preservation.As a cleaning agent in cleaning products,such as

limescale remover and toilet bowl cleaner.

Alkylating agent for Alcohols, carboxylating

agent for tertiary compounds. Rubber industry

Formic acid is a source for a formyl group forexample in the formylation of methylaniline to

N-methylformanilide in toluene



Methyl alcohol

Methanol is used on a limited basis to fuel

internal combustion engines.

Methanol is also used as a solvent, and as anantifreeze in pipelines and windshield washer

fluid.

About 80 per cent of methanol is used for themanufacture of formaldehyde to produce ureaand melamine formaldehyde adhesive resins.



ILLUSTRATIONS

2) Benzaldehyde can be converted to benzoic

acid and benzyl alcohol.



Benzoic Acid uses

Food preservative

Against yeasts and bacteria n a long list of foods such as coffee

extract, cooked pickled meat and pork; jam, jelly and

marmalade; fruit juice, beverages and sherbet and syrups,sauces and tomato paste

chemistry

Benzoic acid is the most commonly used chemical standard to

determine the heat of capacity of a bomb calorimeter Medicinal

Benzoic acid is a constituent of Whitfield's ointment which is

used for the treatment of fungal skin diseases such as tinea,

ringworm, and athlete's foot



Benzyl alcohol uses

Chemistry

Benzyl alcohol is used as a general solvent for inks,

paints, and epoxy resin coatings.

it is also a precursor to a variety of esters, used in the

soap, perfume, and flavor industries.

Food preservative

Against yeasts and bacteria



3) Furfural gives Furoic acid andFurfuryl alcohol in presence of strong

alkali.

ILLUSTRATIONS



Applications

Furoic acid Starting material in numerous furoatester.its

derivative use in flavoring agent and ofcourcepreservative

Furfuryl alcoholUses in the production of foundry resins,

adhesive, welting agent.

as a flavoring agent.

In a cosmetics & fragrance.



4) When a mixture of Formaldehyde and a

non Enolizable aldehyde is treated with a

strong base, the later is preferentially reduced

to alcohol while formaldehyde is oxidized toformic acid. This variant is known as crossed

Cannizzaro reaction .

ILLUSTRATIONS



Crossed Cannizzaro reaction .

Benzyl alcohol and Formic acid areobtained when a mixture of Benzaldehyde and

Formaldehyde is treated with alkali.



5) α-keto aldehyde can be converted to α-

hydroxy carboxylic acids by an

Intermolecular Cannizzaro reaction.

ILLUSTRATIONS



Intramolecular cannizzaro

reactionPhenylglyoxal undergoes intramolecular

cannizzaro reaction by giving Mandelic acid (α-hydroxyphenylacetic acid or 2-Hydroxy-2-

phenylethanoic acid)



Mandelic acid

Mandelic acid

Cosmetics industry because it helps in reducingwrinkles, sign of aging, initial acne

In medical industry uses as a anti bacterial, it is

also an alternative to glycolic acid in skin careproducts.

The drugs cyclandelate and homatropine are

esters of mandelic acid.



6) Phthalaldehyde can undergointramolecular Cannizzaro reaction by giving

(o-hydroxymethyl) benzoic acid.

Intramolecular cannizzaro reactio n



Intramolecular Cannizaro Reaction



Mechanism

Step 1

Step 2

Step 3



The combination of crossed-Cannizaro reaction

and aldol condensation



Industrial importance

The combination of aldol condensation andcrossed-Cannizaro reaction generates polyols

from formaldehyde and other aldehyde.

Used in industry to prepare polyols.

An important use of the reaction is thepreparation of Pentaerythrit from acetaldehyde

Polyols are very useful and find many applications

in industry.



• In this process, advantage is being taken ofthe fact that all α-hydrogen atoms of thealdehyde react with formaldehyde in an aldol

condensation. In a subsequent crossed-Cannizaroreaction, the aldehyde group is then reduced toalcohol with excess formaldehyde .

Idea…….



Step1:Neopentylglycol synthesis

Neopentylglycol (2,2-dimethyl-1,.3-propanediol) is

synthesized from isobutyraldehyde (isobutanal) and

formaldehyde.

The α-hydrogen atom is removed by base followed by

Aldol condensation with formaldehyde.



Step2:Neopentylglycol synthesis

•The reaction is carried out with an excess of

formaldehyde

•. The crossed-Cannizaro reaction yields

Neopentylglycol



Applications

• Neopentylglycol is used in polyesters (for

resins used in airplane or boat

manufacturing), varnish coatings, synthetic

lubricants, and plasticizers.

The neopentyl structure provides excellent

resistance to light, heat and hydrolysis.



Synthesis of pentaerythrit &

trimethylolpropane•The polyols pentaerythrit (2,2-

bis(hydroxymethyl)-1,3-propanediol) and

trimethylolpropane (2-ethyl-2-hydroxymethyl-

1,3-propanediol) are prepared in similar fashion.•



Applications

pentaerythrit is produced inlargest quantities.

Its main use is as raw material inthe varnish industry. Its tetranitrate is an explosive.

Some esters of pentaerythrit withhigher fatty acids are being usedas oil additives, plasticizers andemulsifiers.



But……….

At the present time, various oxidizing andreducing agents can be used to carry outsuch conversions (with higher yields), so theCannizzaro Reaction has limited syntheticutility except for the conversion of α-keto

aldehydes.



Tishchenko reaction

A variant of the Cannizzaro reaction, known as the

Tischenko reaction is a disproportionate reaction ofan Aldehyde lacking a hydrogen atom in the alpha

position in the presence of an Alcoxide. Catalyst

are aluminium alkoxides or sodium alkoxides. In

this reaction the alcohol and acid products combine

to form an ester.



Tishchenko reaction

Para Benzaldehyde



Mechanism of the

Reaction

• One molecule of aluminum alkoxide act as a

Lewis base to Coordinate with one molecule ofthe aldehyde,and to facilate the addition of the

second equivalent of aldehyde generating

Hemiacetal intermediate



Mechanism



Lithium Bromide as a

Flexible, Mild, andRecyclable Reagent forSolvent-Free Cannizzaro,

Tishchenko, and Meerwein-Ponndorf-Verley Reactions

Recent Literature



Recent Literature

►Lithium Bromide as a Flexible, Mild,

and Recyclable Reagent for Solvent-

Free Cannizzaro, Tishchenko, andMeerwein-Ponndorf-Verley Reactions



A convenient disproportionation or reduction

of aldehydes is promoted by lithium bromideand triethylamine in a solvent-free

environment at room temperature.

Recent Literature



Recent Literature



•Products of Cannizzaro or Tishchenko reactions can

be isolated using different workup methods. In the

presence of a hydrogen donor alcohol, a Meerwein-

Ponndorf-Verley reaction takes place.

Meerwein-Ponndorf-Verley

reaction



Meerwein-Ponndorf-Verley reaction



• Ytterbium Triflate-Promoted TandemOne-Pot Oxidation-Cannizzaro

Reaction of Aryl Methyl Ketones

One-Pot Oxidation-Cannizzaro Reaction

of Aryl Methyl Ketones



One-Pot Oxidation-Cannizzaro Reaction

of Aryl Methyl Ketones

. The environmentally friendly synthesis of

mandelic acid derivatives provides products

in excellent yield without any further

purification after the

usual workup.



REFRENCE THAT MAY HELP

YOU



Refrence

Massimo Curini,* Francesco Epifano, Salvatore

Genovese, M. Carla Marcotullio and Ornelio Rosati

*Dipartimento di Chimica e Tecnologia del Farmaco,

Sezione di Chimica Organica, Via del Liceo, 06123

Perugia, Italy, Email: curmax unipg.it

M. Curini, F. Epifano, S. Genovese, M. C. Marcotullio, O.

Rosati, Org. Lett., 2005, 7 , 1331-1333.



Refrence

Mohammad M. Mojtahedi, Elahe Akbarzadeh, Roholah

Sharifi and M. Saeed Abaee*

*Organic Chemistry Department, Chemistry & Chemical

Engineering Research Center of Iran, P.O. Box 14335-186,

Tehran, Iran,

Email: abaeeccerci.ac.irM. M. Mojtahedi, E. Akbarzadeh, R. Sharifi, M. S. Abaee,



Reference

• ADICHEMISTRY: ONLINE CHEMISTRY RESOURCE(ORGANIC, INORGANIC, PHYSICAL & ANALYTICAL FOR CSIR UGCNET, GATE, SAT, IIT-JEE, AIEEE, JAM, AP CHEMISTRY)

;Wikipedia

•.Cobb, Cathy, and Goldwhite, Harold (1995). Creations of Fire: Chemistry's Lively

History from Alchemy to the Atomic Age. New York: Plenum.

•DeMilt, Clara (1965). "The Congress at Karlsruhe." In Selected Readings in the

History of Chemistry , ed. Aaron J. Ihde and William F. Kieffer. Easton, PA:

Division of Chemical Education of the American Chemical Society.

•Ihde, Aaron (1964). The Development of Modern Chemistry. New York: Harper &

Row.

•Partington, J. R. (1989). A Short History of Chemistry. New York: Dover

Publications.•



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