N,N-Diisopropylethylamine, or Hünig's base, DIPEA or DIEA, is an organic compound

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...

 and an 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 Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group.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,...

. It is used in organic chemistry

Organic chemistry

Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...

 as a base

Base (chemistry)

For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...

. Because the nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 atom is shielded by the two isopropyl

Isopropyl

In organic chemistry, isopropyl is a propyl with a group attached to the secondary carbon. If viewed as a functional group an isopropyl is an organic compound with a propyl group attached at its secondary carbon.The bond is therefore on the middle carbon....

 groups and an ethyl group

Ethyl group

In chemistry, an ethyl group is an alkyl substituent derived from ethane . It has the formula -C2H5 and is very often abbreviated -Et.Ethylation is the formation of a compound by introduction of the ethyl functional group, C2H5....

 only a 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: positively charged ions and negatively charged ions....

 is small enough to easily fit. Just like 2,2,6,6-tetramethylpiperidine

2,2,6,6-Tetramethylpiperidine

2,2,6,6-Tetramethylpiperidine or TMP or HTMP is a clear liquid with an amine odor. This amine is used in chemistry as a hindered base because it can dissolve in organic solvents unlike ordinary bases such as potassium hydroxide....

, this compound is a good base but a poor nucleophile

Nucleophile

A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...

, which makes it a useful organic reagent. Hünig's base is named after the German chemist Siegfried Hünig.

Preparation

Hünig's base is commercially available. It is traditionally prepared by the reaction of diisopropylamine

Diisopropylamine

Diisopropylamine is a secondary amine with the chemical formula 2HC-NH-CH2. It is best known as its lithium salt, lithium diisopropylamide, known as "LDA"...

 with diethyl sulfate

Diethyl sulfate

Diethyl sulfate is a highly toxic and likely carcinogenicchemical compound with formula 24. It occurs as a colorless liquid with a peppermint odor.Diethyl sulfate is used as an alkylating agent to prepare ethyl derivatives of phenols, amines, and thiols....

.

Non-nucleophilic base

Hünig's base was investigated for its use as a selective reagent in the 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...

 of secondary amines to tertiary amines by alkyl halides. This organic reaction

Organic reaction

Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis,...

 is often hampered by a quaternization reaction to the quaternary ammonium salt but this side-reaction is absent when Hünig's base is present.

Synthesis of scorpionine

Hünig's base forms a complex heterocyclic compound called scorpionine  by a reaction with disulfur dichloride

Disulfur dichloride

Disulfur dichloride is the chemical compound with the formula S2Cl2 . Some alternative names for this compound are sulfur monochloride , disulphur dichloride and sulphur monochloride...

 catalyzed by DABCO

DABCO

DABCO or 1,4-diazabicyclo[2.2.2]octane is a chemical compound. It is a polyurethane and Baylis-Hillman reaction catalyst, complexing ligand and Lewis base. It is used to regulate the reaction rate in Flexplay time-limited DVDs by adjusting pH. Antioxidants, like DABCO, are used to improve the...

 in a remarkable one-pot synthesis

One-pot synthesis

In chemistry a one-pot synthesis is a strategy to improve the efficiency of a chemical reaction whereby a reactant is subjected to successive chemical reactions in just one reactor...

.