Heck reaction

	Email		Print
	Bookmark		Link

Heck reaction

The Heck reaction (also called the Mizoroki-Heck reaction) is the chemical reaction

Chemical reaction

A chemical reaction is a process that always results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants....
of an unsaturated halide

Halide

A halide is a binary compound, of which one part is a halogen atom and the other part is an chemical element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound....
(or triflate

Triflate

Triflate, more formally known as trifluoromethanesulfonate, is a functional group with the formula CF3SO3-. The triflate group is often represented by -OTf, as opposed to -Tf....
) with an alkene

Alkene

In organic chemistry, an alkene, olefin, or olefine is an Saturation chemical compound containing at least one carbon-to-carbon double bond....
and a strong base

Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
and palladium

Palladium

Palladium is a rare and lustrous silvery-white metal that was discovered in 1803 by William Hyde Wollaston, who named it palladium after the 2 Pallas, which in turn, was named after the epithet of the Greek mythology goddess Athena, acquired by her when she slew Athena#Pallas_Athena....
catalyst to form a substituted alkene. It is named after the American chemist Richard F. Heck

Richard F. Heck

Richard F. Heck is an American chemist known for the Heck reaction. He retired from the University of Delaware in 1989. There, a lectureship was named in his honor in 2004....
.

The reaction is performed in the presence of an organopalladium

Organopalladium

Organopalladium chemistry is a branch of organometallic chemistry that deals with organic palladium compounds and their reactions. Palladium is often used as a catalyst in the reduction of alkenes and alkynes with hydrogen....
catalyst.

Discussion

Ask a question about 'Heck reaction'

Start a new discussion about 'Heck reaction'

Answer questions from other users

Full Discussion Forum

Recent Posts

I'm currently in high school and doing a research project on heck reactions catalysed in water by pi...

What is heck reaction

May u please help with the title of a project i'm looking for the project that can used the Heck rea...

Encyclopedia

The Heck reaction (also called the Mizoroki-Heck reaction) is the chemical reaction

Chemical reaction

Halide

Triflate

Alkene

In organic chemistry, an alkene, olefin, or olefine is an Saturation chemical compound containing at least one carbon-to-carbon double bond....
and a strong base

Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
and palladium

Palladium

Richard F. Heck

Richard F. Heck is an American chemist known for the Heck reaction. He retired from the University of Delaware in 1989. There, a lectureship was named in his honor in 2004....
.

The reaction is performed in the presence of an organopalladium

Organopalladium

Aryl

In the context of organic molecules, aryl refers to any functional group or substituent derived from a simple aromatic ring, may it be phenyl, thiophene, indole, etc ....
, benzyl

Benzyl

In organic chemistry, benzyl is the term used to describe the substituent or molecular fragment possessing the structure C6H5CH2-....
, or vinyl

Vinyl

A vinyl compound is any organic compound that contains a vinyl group , −CarbonHydrogenCovalent bondCH2. These are derivatives of ethene, CH2=CH2, with one hydrogen atom replaced with some other group....
compound and the alkene contains at least one proton

Hydrogen ion

Hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes. Depending on the charge of the ion, two different classes can be distinguished:...
and is often electron-deficient such as acrylate

Acrylate

The acrylate ion is the ion of acrylic acid.Acrylates are the salts and esters of acrylic acid. They are also known as propenoates ....
ester

Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
or an acrylonitrile

Acrylonitrile

Acrylonitrile is the chemical compound with the formula CH2CHCN. This pungent-smelling colorless liquid often appears yellow due to impurities....
.The catalyst can be tetrakis(triphenylphosphine)palladium(0)

Tetrakis(triphenylphosphine)palladium(0)

Tetrakispalladium is the chemical compound Pd[P3]4, often abbreviated Pd4, or even PdP4. It is a bright yellow crystalline solid that becomes brown upon decomposition in air....
, palladium chloride or palladium(II) acetate

Palladium(II) acetate

Palladium acetate is a chemical compound of palladium described by the formula Pd2 or Pd2. It is considered more reactive than the related platinum....
. The ligand

Ligand

In chemistry, a ligand is either an atom, ion, or molecule that bonds to a central metal, generally involving formal donation of one or more of its electrons....
is triphenylphosphine

Triphenylphosphine

Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PhosphorusPhenyl group or Ph3P....
or BINAP

BINAP

BINAP is an acronym for the organophosphorus compound 2,2'-bis-1,1'-binaphthyl. This Optical isomerism ligand is widely used in chiral synthesis....
. The base is triethylamine

Triethylamine

Triethylamine is the chemical compound with the chemical formula N3, commonly abbreviated ethyl group3N or TEA. It is a commonly encountered in organic synthesis probably because it is the simplest symmetrically trisubstituted amine, i.e....
, potassium carbonate

Potassium carbonate

Sodium acetate

Sodium acetate, is the sodium Salt of acetic acid. It is an inexpensive chemical produced in industrial quantities for a wide range of uses....
.

Several reviews have been published.

This coupling reaction

Coupling reaction

A coupling reaction in organic chemistry is a catch-all for a range of reactions in Organometallic chemistry where two hydrocarbon free radical are coupled with the aid of a metal containing catalyst....
is stereoselective with a propensity for trans coupling as the palladium halide group and the bulky organic residue move away from each other in the reaction sequence in a rotation step. The Heck reaction is applied industrially in the production of naproxen

Naproxen

Naproxen is a non-steroidal anti-inflammatory drug commonly used for the reduction of moderate to severe pain, fever, inflammation and stiffness caused by conditions such as osteoarthritis, rheumatoid arthritis, psoriatic arthritis, gout, ankylosing spondylitis, menstrual cramps, tendinitis, bursitis, and the treatment of primary dysmenorr...
and the sunscreen

Sunscreen

Sunscreen is a lotion, spray, gel or other topical product that absorbs or reflects the sun's ultraviolet radiation and protects the skin.Sunscreens contain one or more UV filters of which there are three main types :...
component octyl methoxycinnamate

Octyl methoxycinnamate

Octyl methoxycinnamate or octinoxate , trade names Eusolex 2292 and Tinosorb OMC, is an organic compound that is an ingredient in some sunscreens and lip balms....
. The naproxen synthesis includes a coupling between a brominated naphthalene

Naphthalene

Naphthalene, also known as naphthalin, naphthaline, tar camphor, white tar, albocarbon, or antimite and not to be confused with naphtha, is a crystalline, Aromaticity, white, solid hydrocarbon with formula Carbon10hydrogen8 and the structure of two fused benzene rings....
compound with ethylene

Ethylene

Ethylene is the chemical compound with the formula C2H4. It is the simplest alkene. Because it contains a carbon-carbon double bond, ethylene is called an unsaturated hydrocarbon or an olefin....
:

Reaction mechanism

The catalytic cycle

Catalytic cycle

A catalytic cycle in chemistry is a term for a multistep reaction mechanism that involves a catalyst . The catalytic cycle is the main method for describing the role of catalysts in biochemistry, organometallic chemistry, materials science, etc....
for the Heck reaction involves a series of transformations around the palladium catalyst. The palladium(0) compound required in this cycle is generally prepared in situ

In situ

In situ is a Latin phrase meaning in the place. It is used in many different contexts....
from a palladium(II) precursor.

For instance, palladium(II) acetate

Palladium(II) acetate

Palladium acetate is a chemical compound of palladium described by the formula Pd2 or Pd2. It is considered more reactive than the related platinum....
is reduced by triphenylphosphine

Triphenylphosphine

Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PhosphorusPhenyl group or Ph3P....
to di(triphenylphosphine)palladium(0) and triphenylphosphine is oxidized to triphenylphosphine oxide in step 1. Step 2 is an oxidative addition

Oxidative addition

Oxidative addition and reductive elimination are two important classes of reactions in organometallic chemistry . Their relationship is shown below where y represents the number of ligands on the metal and n is the oxidation state of the metal....
in which palladium inserts itself in the aryl to bromide bond. In step 3, palladium forms a p complex with the alkene and in step 4 the alkene inserts itself in the palladium - carbon bond in a syn addition

Syn addition

In organic chemistry, syn and anti addition are different ways in which two substituents can be added to a double bond or triple bond. This article will use alkenes as examples....
step. Step 5 is a torsional strain relieving rotation and step 6 is a Beta-hydride elimination

Beta-hydride elimination

Beta-hydride elimination is a reaction in which an alkyl group bonded to a metal centre is converted into the corresponding metal-bonded hydride and an alkene....
step with the formation of a new palladium - alkene p complex. This complex is destroyed in step 7. The palladium(0) compound is regenerated by reductive elimination of the palladium(II) compound by potassium carbonate

Potassium carbonate

Potassium carbonate is a white salt, soluble in water , which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide....
in the final step 8. In the course of the reaction the carbonate is stoichiometrically consumed and palladium is truly a catalyst and used in catalytic amounts. A similar palladium cycle but with different scenes and actors is observed in the Wacker process

Wacker process

The Wacker process or the Hoechst-Wacker process originally referred to the oxidation of ethylene to acetaldehyde by oxygen in water in the presence of a tetrachloropalladate catalysis....
.

This cycle is not limited to vinyl compounds, in the Sonogashira coupling

Sonogashira coupling

In organic chemistry, a Sonogashira coupling is a coupling reaction of terminal alkynes with aryl or vinyl halides. This reaction was first reported by Kenkichi Sonogashira and Nobue Hagihara in 1975....
one of the reactants is an alkyne

Alkyne

Alkynes are hydrocarbons that have at least one triple bond between two carbon atoms, with the formula CnH2n-2. The alkynes are traditionally known as acetylenes or the acetylene series, although the name acetylene is also used to refer specifically to the simplest member of the series, known as e...
and in the Suzuki coupling the alkene is replaced by an aryl boronic acid

Boronic acid

A boronic acid is an alkyl or aryl substituted boric acid containing a carbon to boron chemical bond belonging to the larger class of organoboranes....
and in the Stille reaction

Stille reaction

The Stille reaction is a chemical reaction coupling an organotin compound with an sp2-hybridized organic halide catalyzed by palladium....
by an aryl stannane

Stannane

Stannane is the hydride of tin. Stannane can be prepared by the reaction of tin chloride and lithium aluminium hydride. Stannane decomposes slowly at room temperature to give metallic tin and hydrogen and ignites on contact with air....
. The cycle also extends to the other group 10 element

Group 10 element

A Group 10 element is one in the chemical series of Chemical element in periodic table group 10 in the periodic table, which consists of the transition metals nickel , palladium , platinum , and darmstadtium ....
nickel

Nickel

Nickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge....
for example in the Negishi coupling

Negishi coupling

The Negishi coupling is a cross coupling reaction in organic chemistry involving an organozinc compound, an organic halide and a nickel or palladium catalyst creating a new carbon-carbon covalent bond :...
between aryl halides and organozinc compounds. Platinum forms strong bonds with carbon and does not have a catalytic activity in this type of reaction.

Variations

Ionic liquid Heck reaction

In the presence of an ionic liquid

Ionic liquid

An ionic liquid is a liquid that contains essentially only ion s. Some ionic liquids, such as ethylammonium nitrate are in a dynamic equilibrium where at any time more than 99.99% of the liquid is made up of ionic rather than molecular species....
a Heck reaction proceeds in absence of a phosphorus ligand. In one modification palladium acetate and the ionic liquid (bmim)PF₆ are immobilized inside the cavities of reversed-phase silica gel

Silica gel

Silica gel is a granularity, vitreous, highly porosity form of silica made synthetically from sodium silicate. Despite its name, silica gel is a solid....
. In this way the reaction proceeds in water and the catalyst is re-usable.

Heck oxyarylation

In the Heck oxyarylation modification the palladium substituent in the syn-addition intermediate is displaced by a hydroxyl group and the reaction product contains a tetrahydrofuran

Tetrahydrofuran

Tetrahydrofuran is a colorless, water-miscible organic liquid with low-viscosity at "room" temperature and pressure . It is a Heterocyclic compound compound with a chemical formula C4H8O, and is the fully Hydrogenation analog of the aromatic organic compound furan....
ring.

Amino-Heck reaction

In the amino-Heck reaction a nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
to carbon

Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
bond is formed. In one example, an oxime

Oxime

An oxime is one in a class of chemical compounds with the general formula R1R2carbonnitrogenoxygenhydrogen, where R1 is an organic compound side chain and R2 is either hydrogen, forming an aldoxime, or another organic group, forming a ketoxime....
with a strongly electron withdrawing group reacts intramolecular

Intramolecular

Intramolecular in chemistry describes a process or characteristic limited within the structure of a single molecule; a property or phenomenon limited to the extent of a single molecule....
ly with the terminal end of a diene

Diene

Dienes or diolefins are hydrocarbons which contain two covalent bond. Dienes are intermediate between alkenes and polyenes....
to a pyridine

Pyridine

Pyridine is a simple and important heterocyclic aromatic organic compound with the formula CarbonHydrogenNitrogen. This colorless liquid with a distinctive fish-like odor is structurally related to benzene, wherein one CH group in the six-membered ring is replaced by a nitrogen atom....
compound. The catalyst is tetrakis(triphenylphosphine)palladium(0)

Tetrakis(triphenylphosphine)palladium(0)

Triethylamine

External links

The Heck reaction at organic-chemistry.org
Industrial Heck chemistry at www.albemarle.com
The Heck reaction handout from the

Heck reaction

Reaction mechanism

Variations

Ionic liquid Heck reaction

Heck oxyarylation

Amino-Heck reaction

See also

Further reading

External links