Diethyl azodicarboxylate
Encyclopedia
Diethyl azodicarboxylate, conventionally abbreviated as DEAD and sometimes as DEADCAT, is an organic compound
with the structural formula CH3CH2O2CN=NCO2CH2CH3. Its molecular structure consists of a central azo
functional group
, RN=NR, flanked by two ethyl ester
groups. This orange-red liquid is a valuable reagent but also quite dangerous and explodes upon heating. Therefore, commercial shipment of pure diethyl azodicarboxylate is prohibited in the United States and is carried out either in solution or on polystyrene
particles.
DEAD is an aza-dienophile and an efficient dehydrogenating agent, converting alcohol
s to aldehyde
s, thiol
s to disulfide
s and hydrazo groups to azo groups
; it is also a good electron acceptor. While DEAD is used in numerous chemical reactions, it is mostly known as the principal component of the Mitsunobu reaction
, which is daily carried out in chemical laboratories, and can be used for the synthesis of various natural products and pharmaceuticals. In particular, the resulting chemical zidovudine
is a major drug against AIDS
and FdUMP is a potent antitumor agent.
, ethanol
, tetrahydrofuran
and dichloromethane
but has low solubility in water or carbon tetrachloride
; the solubility in water is higher for the related azo compound dimethyl azodicarboxylate.
DEAD is a strong electron acceptor and easily oxidizes a solution of sodium iodide
in glacial acetic acid
. It also reacts vigorously with hydrazine
hydrate
producing diethyl hydrazodicarboxylate and evolving nitrogen. Linear combination of atomic orbitals molecular orbital method
(LCAO-MO) calculations suggest that the molecule of DEAD is unusual in having a highly lying vacant bonding orbital, and therefore tends to withdraw hydrogen atoms from various hydrogen donors. Photoassisted removal of hydrogen by DEAD was demonstrated for isopropyl alcohol
, resulting in pinacol
and tetraethyl tetrazanetetracarboxylate, and for acetaldehyde
yielding diacetyl
and diethyl hydrazodicarboxylate. Similarly, reacting DEAD with ethanol and cyclohexanol
abstracts hydrogen producing acetaldehyde
and cyclohexanone
. Those reactions also proceed without light, although at much lower yields. Thus, in general DEAD is an aza-dienophile and dehydrogenating agent, converting alcohol
s to aldehyde
s, thiol
s to disulfide
s and hydrazo groups to azo groups
. It also joins pericyclic reaction
s with alkene
s and diene
s via Ene
and Diels–Alder mechanisms.
, first by alkylation
with ethyl chloroformate
, followed by treating the resulting diethyl hydrazodicarboxylate with chlorine
(bubbling through the solution), hypochlorous acid
, concentrated nitric acid
or red fuming nitric acid
. The reaction is carried out in an ice bath, and the reagents are added dropwise so that the temperature does not rise above 20 °C. Diethyl hydrazodicarboxylate is a solid with melting temperature of 131–133 °C which is collected as a residue; it is significantly more stable to heating than DEAD and is conventionally dried at a temperature of about 80 °C.
in the Mitsunobu reaction
where it forms an adduct with phosphines (usually triphenylphosphine
) and assists the synthesis of ester
s, ether
s, amine
s and thioether
s of alcohols. Reactions normally result in the inversion
of molecular symmetry.
DEAD was used in the original 1967 article by Oyo Mitsunobu, and his 1981 review on the use of diethyl azodicarboxylate is a top-cited chemistry article. Mitsunobu reaction has several applications in the synthesis of natural products and pharmaceuticals.
In the above reaction, which is assisted either by DEAD or DIAD
(diisopropyl azodicarboxylate), thymidine
1 transforms to the derivative 2. The latter easily converts to zidovudine
4 (also known as azidothymidine or AZT), an important antiviral drug, used among others in the treatment of AIDS
. Another example of pharmaceutical application of DEAD-assisted Mitsunobu reaction is the synthesis of bis[(pivaloyloxy)methyll [PIVz] derivative of 2’-deoxy-5-fluorouridine 5’-monophosphate (FdUMP), which is a potent antitumor agent.
. In the presence of a copper(II) catalyst, DEAD assists conversion of β-keto esters to the corresponding hydrazine derivatives.
Similarly proceeds substitution of boronic acid
esters:
s and in click chemistry
, for example the synthesis of bicyclo[2.1.0]pentane, which originates from Otto Diels
. It has also been used to generate aza-Baylis-Hillman adducts with acrylates.
DEAD can be used for synthesis of heterocyclic compound
s. Thus, pyrazoline derivatives convert by condensation
to α,β-unsaturated ketone
s:
Another application is the use of DEAD as enophile in Ene reaction
s:
polystyrene
particles at a concentration of about 1 mmol
/g. The time-weighed average threshold limit value
for exposure to DEAD over a typical 40-hour working week is 50 parts per million; that is, DEAD is half as toxic as, e.g., carbon monoxide
. Safety hazards have resulted in rapid decline of DEAD usage and replacement with DIAD
and other similar compounds.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with the structural formula CH3CH2O2CN=NCO2CH2CH3. Its molecular structure consists of a central azo
Azo compound
Azo compounds are compounds bearing the functional group R-N=N-R', in which R and R' can be either aryl or alkyl. IUPAC defines azo compounds as: "Derivatives of diazene , HN=NH, wherein both hydrogens are substituted by hydrocarbyl groups, e.g. PhN=NPh azobenzene or diphenyldiazene." The more...
functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
, RN=NR, flanked by two ethyl ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
groups. This orange-red liquid is a valuable reagent but also quite dangerous and explodes upon heating. Therefore, commercial shipment of pure diethyl azodicarboxylate is prohibited in the United States and is carried out either in solution or on polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
particles.
DEAD is an aza-dienophile and an efficient dehydrogenating agent, converting alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s to aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
s, thiol
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
s to disulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
s and hydrazo groups to azo groups
Azo compound
Azo compounds are compounds bearing the functional group R-N=N-R', in which R and R' can be either aryl or alkyl. IUPAC defines azo compounds as: "Derivatives of diazene , HN=NH, wherein both hydrogens are substituted by hydrocarbyl groups, e.g. PhN=NPh azobenzene or diphenyldiazene." The more...
; it is also a good electron acceptor. While DEAD is used in numerous chemical reactions, it is mostly known as the principal component of the Mitsunobu reaction
Mitsunobu reaction
The Mitsunobu reaction is an organic reaction that converts an alcohol into a variety of functional groups, such as an ester, using triphenylphosphine and an azodicarboxylate such as diethyl azodicarboxylate or diisopropyl azodicarboxylate . The alcohol undergoes an inversion of stereochemistry...
, which is daily carried out in chemical laboratories, and can be used for the synthesis of various natural products and pharmaceuticals. In particular, the resulting chemical zidovudine
Zidovudine
Zidovudine or azidothymidine is a nucleoside analog reverse-transcriptase inhibitor , a type of antiretroviral drug used for the treatment of HIV/AIDS. It is an analog of thymidine....
is a major drug against AIDS
AIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
and FdUMP is a potent antitumor agent.
Properties
DEAD is an orange-red liquid which weakens its color to yellow or colorless upon dilution or chemical reaction. This color change is conventionally used for visual monitoring of the synthesis. DEAD dissolves in most common organic solvents, such as toluene, chloroformChloroform
Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous...
, ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
, tetrahydrofuran
Tetrahydrofuran
Tetrahydrofuran is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. This heterocyclic compound has the chemical formula 4O. As one of the most polar ethers with a wide liquid range, it is a useful solvent. Its main use, however, is as a precursor...
and dichloromethane
Dichloromethane
Dichloromethane is an organic compound with the formula CH2Cl2. This colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. Although it is not miscible with water, it is miscible with many organic solvents...
but has low solubility in water or carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
; the solubility in water is higher for the related azo compound dimethyl azodicarboxylate.
DEAD is a strong electron acceptor and easily oxidizes a solution of sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....
in glacial acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
. It also reacts vigorously with hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
hydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
producing diethyl hydrazodicarboxylate and evolving nitrogen. Linear combination of atomic orbitals molecular orbital method
Linear combination of atomic orbitals molecular orbital method
A linear combination of atomic orbitals or LCAO is a quantum superposition of atomic orbitals and a technique for calculating molecular orbitals in quantum chemistry. In quantum mechanics, electron configurations of atoms are described as wavefunctions...
(LCAO-MO) calculations suggest that the molecule of DEAD is unusual in having a highly lying vacant bonding orbital, and therefore tends to withdraw hydrogen atoms from various hydrogen donors. Photoassisted removal of hydrogen by DEAD was demonstrated for isopropyl alcohol
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...
, resulting in pinacol
Pinacol
Pinacol is a white solid organic compound.-Preparation:It may be produced by the pinacol coupling reaction from acetone:-Reactions:As a vicinal-diol, it can rearrange to pinacolone by the pinacol rearrangement, e.g...
and tetraethyl tetrazanetetracarboxylate, and for acetaldehyde
Acetaldehyde
Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...
yielding diacetyl
Diacetyl
Diacetyl is a natural byproduct of fermentation. It is a vicinal diketone with the molecular formula C4H6O2...
and diethyl hydrazodicarboxylate. Similarly, reacting DEAD with ethanol and cyclohexanol
Cyclohexanol
Cyclohexanol is the organic compound with the formula 5CHOH. The molecule is related to cyclohexane ring by replacement of one hydrogen atom by a hydroxyl group. This compound exists as a deliquescent colorless solid, which, when very pure, melts near room temperature...
abstracts hydrogen producing acetaldehyde
Acetaldehyde
Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...
and cyclohexanone
Cyclohexanone
Cyclohexanone is the organic compound with the formula 5CO. The molecule consists of six-carbon cyclic molecule with a ketone functional group. This colorless oil has an odor reminiscent of peardrop sweets as well as acetone. Over time, samples assume a yellow color due to oxidation...
. Those reactions also proceed without light, although at much lower yields. Thus, in general DEAD is an aza-dienophile and dehydrogenating agent, converting alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s to aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
s, thiol
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
s to disulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
s and hydrazo groups to azo groups
Azo compound
Azo compounds are compounds bearing the functional group R-N=N-R', in which R and R' can be either aryl or alkyl. IUPAC defines azo compounds as: "Derivatives of diazene , HN=NH, wherein both hydrogens are substituted by hydrocarbyl groups, e.g. PhN=NPh azobenzene or diphenyldiazene." The more...
. It also joins pericyclic reaction
Pericyclic reaction
In organic chemistry, a pericyclic reaction is a type of organic reaction wherein the transition state of the molecule has a cyclic geometry, and the reaction progresses in a concerted fashion. Pericyclic reactions are usually rearrangement reactions...
s with alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
s and diene
Diene
In organic chemistry a diene or diolefin is a hydrocarbon that contains two carbon double bonds.Conjugated dienes are functional groups, with a general formula of CnH2n-2. Dienes and alkynes are functional isomers...
s via Ene
Ene reaction
The Ene reaction is a chemical reaction between an alkene with an allylic hydrogen and a compound containing a multiple bond , in order to form a new σ-bond with migration of the ene double bond and 1,5 hydrogen shift. The product is a substituted alkene with the double bond shifted to the...
and Diels–Alder mechanisms.
Preparation
Although available commercially, diethyl azodicarboxylate is often prepared fresh in the laboratory, especially if required in pure, non-diluted form. A two-step synthesis starts from hydrazineHydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
, first by alkylation
Alkylation
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene . Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in...
with ethyl chloroformate
Ethyl chloroformate
Ethyl chloroformate is the ethyl ester of chloroformic acid. It is a reagent used in organic synthesis for the introduction of the ethyl carbamate protecting group and for the formation of carboxylic anhydrides....
, followed by treating the resulting diethyl hydrazodicarboxylate with chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
(bubbling through the solution), hypochlorous acid
Hypochlorous acid
Hypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor...
, concentrated nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
or red fuming nitric acid
Red fuming nitric acid
Red fuming nitric acid is a storable oxidizer used as a rocket propellant. It consists mainly of nitric acid , also containing 13% dinitrogen tetroxide and 3% water. The dissolved nitrogen dioxide is very concentrated and can be found at room temperature...
. The reaction is carried out in an ice bath, and the reagents are added dropwise so that the temperature does not rise above 20 °C. Diethyl hydrazodicarboxylate is a solid with melting temperature of 131–133 °C which is collected as a residue; it is significantly more stable to heating than DEAD and is conventionally dried at a temperature of about 80 °C.
Mitsunobu reaction
DEAD is an important reagentReagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
in the Mitsunobu reaction
Mitsunobu reaction
The Mitsunobu reaction is an organic reaction that converts an alcohol into a variety of functional groups, such as an ester, using triphenylphosphine and an azodicarboxylate such as diethyl azodicarboxylate or diisopropyl azodicarboxylate . The alcohol undergoes an inversion of stereochemistry...
where it forms an adduct with phosphines (usually triphenylphosphine
Triphenylphosphine
Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...
) and assists the synthesis of ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s, ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
s, amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s and thioether
Thioether
A thioether is a functional group in organosulfur chemistry with the connectivity C-S-C as shown on right. Like many other sulfur-containing compounds, volatile thioethers have foul odors. A thioether is similar to an ether except that it contains a sulfur atom in place of the oxygen...
s of alcohols. Reactions normally result in the inversion
Stereoisomerism
Stereoisomers are isomeric molecules that have the same molecular formula and sequence of bonded atoms , but that differ only in the three-dimensional orientations of their atoms in space. This contrasts with structural isomers, which share the same molecular formula, but the bond connections...
of molecular symmetry.
DEAD was used in the original 1967 article by Oyo Mitsunobu, and his 1981 review on the use of diethyl azodicarboxylate is a top-cited chemistry article. Mitsunobu reaction has several applications in the synthesis of natural products and pharmaceuticals.
In the above reaction, which is assisted either by DEAD or DIAD
Diad
The diad is a structure in the cardiac myocyte located at the sarcomere Z-line. It is composed of a single t-tubule paired with a terminal cisterna of the sarcoplasmic reticulum. The diad plays an important role in excitation-contraction coupling by juxtaposing an inlet for the action potential...
(diisopropyl azodicarboxylate), thymidine
Thymidine
Thymidine is a chemical compound, more precisely a pyrimidine deoxynucleoside. Deoxythymidine is the DNA nucleoside T, which pairs with deoxyadenosine in double-stranded DNA...
1 transforms to the derivative 2. The latter easily converts to zidovudine
Zidovudine
Zidovudine or azidothymidine is a nucleoside analog reverse-transcriptase inhibitor , a type of antiretroviral drug used for the treatment of HIV/AIDS. It is an analog of thymidine....
4 (also known as azidothymidine or AZT), an important antiviral drug, used among others in the treatment of AIDS
AIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
. Another example of pharmaceutical application of DEAD-assisted Mitsunobu reaction is the synthesis of bis[(pivaloyloxy)methyll [PIVz] derivative of 2’-deoxy-5-fluorouridine 5’-monophosphate (FdUMP), which is a potent antitumor agent.
Michael reaction
The azo group in DEAD is a Michael acceptorMichael reaction
The Michael reaction or Michael addition is the nucleophilic addition of a carbanion or another nucleophile to an alpha, beta unsaturated carbonyl compound. It belongs to the larger class of conjugate additions. This is one of the most useful methods for the mild formation of C-C bonds...
. In the presence of a copper(II) catalyst, DEAD assists conversion of β-keto esters to the corresponding hydrazine derivatives.
Similarly proceeds substitution of boronic acid
Boronic acid
A boronic acid is an alkyl or aryl substituted boric acid containing a carbon–boron bond belonging to the larger class of organoboranes. Boronic acids act as Lewis acids. Their unique feature is that they are capable of forming reversible covalent complexes with sugars, amino acids, hydroxamic...
esters:
Other reactions
DEAD is an efficient component in Diels-Alder reactionDiels-Alder reaction
The Diels–Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. The reaction can proceed even if some of the atoms in the newly formed ring are not carbon...
s and in click chemistry
Click chemistry
Click chemistry is a chemical philosophy introduced by K. Barry Sharpless of The Scripps Research Institute, in 2001 and describes chemistry tailored to generate substances quickly and reliably by joining small units together...
, for example the synthesis of bicyclo[2.1.0]pentane, which originates from Otto Diels
Otto Diels
Otto Paul Hermann Diels was a German chemist. He was the son of a professor of philology at the University of Berlin, where he himself earned his doctorate in chemistry, in the group of Emil Fischer....
. It has also been used to generate aza-Baylis-Hillman adducts with acrylates.
DEAD can be used for synthesis of heterocyclic compound
Heterocyclic compound
A heterocyclic compound is a cyclic compound which has atoms of at least two different elements as members of its ring. The counterparts of heterocyclic compounds are homocyclic compounds, the rings of which are made of a single element....
s. Thus, pyrazoline derivatives convert by condensation
Condensation reaction
A condensation reaction is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction; other possible small molecules lost are hydrogen chloride,...
to α,β-unsaturated ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
s:
Ene reaction
The Ene reaction is a chemical reaction between an alkene with an allylic hydrogen and a compound containing a multiple bond , in order to form a new σ-bond with migration of the ene double bond and 1,5 hydrogen shift. The product is a substituted alkene with the double bond shifted to the...
s:
Safety
DEAD is toxic, shock and light sensitive; it can violently explode when its undiluted form is heated above 100 °C. Shipment of pure diethyl azodicarboxylate is prohibited in the United States and is carried out in solution, typically about 40% DEAD in toluene. Alternatively, DEAD is transported and stored on 100–300 meshMesh (scale)
Mesh material is often used in determining the particle size distribution of a granular material. For example, a sample from a truckload of peanuts may be placed atop a mesh with 5 mm openings. When the mesh is shaken, small broken pieces and dust pass through the mesh while whole peanuts are...
polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
particles at a concentration of about 1 mmol
Mole (unit)
The mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as an amount of a substance that contains as many elementary entities as there are atoms in 12 grams of pure carbon-12 , the isotope of carbon with atomic weight 12. This corresponds to a value...
/g. The time-weighed average threshold limit value
Threshold Limit Value
The threshold limit value of a chemical substance is a level to which it is believed a worker can be exposed day after day for a working lifetime without adverse health effects. Strictly speaking, TLV is a reserved term of the American Conference of Governmental Industrial Hygienists...
for exposure to DEAD over a typical 40-hour working week is 50 parts per million; that is, DEAD is half as toxic as, e.g., carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
. Safety hazards have resulted in rapid decline of DEAD usage and replacement with DIAD
Diad
The diad is a structure in the cardiac myocyte located at the sarcomere Z-line. It is composed of a single t-tubule paired with a terminal cisterna of the sarcoplasmic reticulum. The diad plays an important role in excitation-contraction coupling by juxtaposing an inlet for the action potential...
and other similar compounds.