Cannizaro rxn

Cannizzaro reaction

IntroductionSynthesis

ApplicationVariants

Recent literature

Stanislao Cannizaro was an Italian Chemist.

1826-1910

Cannizzaro reaction

The first to clearify the difference between Molecular and Atomic weights

In 1858 Cannizzaro published his "Sketch of a Course in Chemical

Philosophy" in the journal Il Nuovo Cimento , in which he undertook to

resolve many of chemistry's outstanding issues, basing his arguments on the

work of Avogadro

Stanislao Cannizaro

Only works with aldehydes that are

non-enolisable, i.e. does not have any α-protons.

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

Applicability

Aldehyde containing NO Alpha hydrogen undergo 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 corresponding alcohol, while a second one is oxidized to the carboxylic

acid.

The applicability of Cannizzaro reaction in organic synthesis is limited as the yield

is not more than 50% for either acid or alcohol formed.

The α,α,α-Trihalo aldehyde undergo haloform reaction in strongly alkaline

medium. E.g. Choral will give chloroform in presence of an alkali.

Explanation

Explanation

Involves the bas-induced disproportionation of an aldehyde 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 slowly when electron-donating groups are present. But the reaction 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 D2O as solvent, the resulting alcohol does not show carbon bonded deuterium. It indicates the hydrogen is transferred from the second aldehyde molecule, and not from the solvent.

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 in strong alkali.

ILLUSTRATIONS

Formic acid

It is used for decalcifier, reducer in dyeing for wool 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 for example 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 an antifreeze in pipelines and

windshield washer fluid.

About 80 per cent of methanol is used for the manufacture of formaldehyde to

produce urea and melamine formaldehyde adhesive resins.

ILLUSTRATIONS

2) Benzaldehyde can be converted to benzoic acid and benzyl alcohol.

Benzoic Acid uses

Food preservativeAgainst 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

chemistryBenzoic acid is the most commonly used chemical

standard to determine the heat of capacity of a bomb calorimeter

MedicinalBenzoic 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 preservativeAgainst yeasts and bacteria

3) Furfural gives Furoic acid and

Furfuryl alcohol in presence of strong alkali.

ILLUSTRATIONS

Applications

Furoic acid Starting material in numerous

furoatester.its derivative use in flavoring agent and ofcource preservative

Furfuryl alcohol Uses 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 to formic acid. This variant is known as

crossed Cannizzaro reaction.

ILLUSTRATIONS

Crossed Cannizzaro reaction.

Benzyl alcohol and Formic acid are obtained 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 reaction

Phenylglyoxal 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

reducing wrinkles, sign of aging, initial acne

In medical industry uses as a anti bacterial, it is also an alternative to glycolic acid in skin care products.

The drugs cyclandelate and homatropine are esters of mandelic acid.

6) Phthalaldehyde can undergo

intramolecular Cannizzaro reaction by giving (o-hydroxymethyl) benzoic acid.

Intramolecular cannizzaro reaction

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 and crossed-Cannizaro reaction generates polyols from formaldehyde and other aldehyde.

Used in industry to prepare polyols.

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

Polyols are very useful and find many applications in industry.

• In this process, advantage is being taken of the fact that all α-hydrogen atoms of the aldehyde react with formaldehyde in an aldol condensation. In a subsequent crossed-Cannizaro reaction, the aldehyde group is then reduced to alcohol 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 in largest quantities.

Its main use is as raw material in the varnish industry.

Its tetranitrate is an explosive. Some esters of pentaerythrit

with higher fatty acids are being used as oil additives, plasticizers and emulsifiers.

Applications

Because of its low-cost synthesis, trimethylolpropane has been used in many applications as a glycerin substitute, for example in alkyd resins.

Similar to other polyols, it is being used for the preparation of polyesters and polyurethanes

A solvent-free reaction has been reported involving mixing 2-chlorobenzaldehyde with potassium hydroxide in a mortar & pestle.

Solvent free Cannizzaro

For preparative purposes, the

Cannizaro reaction as such is rather unimportant, because one equivalent of aldehyde generates only half an equivalent each of acid and alcohol.

But…….

Recent Literature

But……….

At the present time, various oxidizing and reducing agents can be used to carry out such conversions (with higher yields), so the Cannizzaro Reaction has limited synthetic utility 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 of an 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 of the aldehyde,and to facilate the addition of the second equivalent of aldehyde generating Hemiacetal intermediate

Mechanism

This species undergoes an

intramolecular 1,3-hydride shift that results in the production of the aluminium-coordinated ester

CONTINUED

Lithium Bromide as a

Flexible, Mild, and Recyclable Reagent for Solvent-Free Cannizzaro, Tishchenko, and Meerwein-Ponndorf-Verley Reactions

Recent Literature

Recent Literature

►Lithium Bromide as a Lithium Bromide as a Flexible, Mild, and Recyclable Flexible, Mild, and Recyclable Reagent for Solvent-Free Reagent for Solvent-Free Cannizzaro, Tishchenko, and Cannizzaro, Tishchenko, and Meerwein-Ponndorf-Verley Meerwein-Ponndorf-Verley ReactionsReactions

Recent Literature

A convenient disproportionation or reduction of aldehydes is promoted by lithium bromide and 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

Tandem One-Pot Oxidation-Cannizzaro Reaction of Aryl Methyl Ketones

One-Pot Oxidation-Cannizzaro Reaction of Aryl Methyl Ketones

Recent literature

• Ytterbium triflate is an effective catalyst for the synthesis of either isopropyl esters or free α-hydroxy-arylacetic acids (mandelic acid derivatives) from substituted aromatic glyoxals and aryl methyl ketenes, respectively.

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.

One-Pot Oxidation-Cannizzaro Reaction of Aryl Methyl Ketones

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.

•^ Cannizzaro, S. (1853). "Ueber den der Benzoësäure entsprechenden Alkohol". Liebigs Annalen 88: 129–130.

•^ List, K.; Limpricht, H. (1854). "Ueber das sogenannte Benzoëoxyd und einige andere gepaarte Verbindungen". Liebigs Annalen 90 (2): 190–210

•. •^ Geissman, T. A. Org. React. 1944, 2, 94. (Review)

•^ A Facile Solvent-Free Cannizzaro Reaction Phonchaiya, Sonthi; ; Panijpan, Bhinyo Rajviroongit, Shuleewan; Wright, Tony; Blanchfield, Joanne T. J. Chem. Educ. 2009,

Refrence

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

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;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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Cannnizzaro Reaction by Marvi jabbar

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