# N,N-Diisopropylethylamine
**N,N-Diisopropylethylamine** (DIPEA), also called **Hünig's base**, is a sterically hindered, non-nucleophilic tertiary amine with the formula C₈H₁₉N, used in organic synthesis to neutralize acids and promote reactions without attacking electrophilic substrates.[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine) • [2](https://www.jove.com/topics/chemistry/diisopropylethylamine-dipea) Its CAS Registry Number is 7087-68-5, and its IUPAC name is N-ethyl-N-propan-2-ylpropan-2-amine.[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine) • [3](https://webbook.nist.gov/cgi/cbook.cgi?ID=7087-68-5&Units=SI) The name honors the German chemist Siegfried Hünig, and the compound appears in the literature under the synonyms ethyldiisopropylamine, N-ethyldiisopropylamine, and Hünig's reagent.[3](https://webbook.nist.gov/cgi/cbook.cgi?ID=7087-68-5&Units=SI)
| Key fact | Detail |
|---|---|
| Identity | Tertiary amine, C₈H₁₉N, molecular weight 129.24 g/mol, CAS 7087-68-5[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine) |
| Physical form | Clear colorless liquid; boiling point 126.5 °C at 760 mmHg; density 0.742 at 25 °C[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine) |
| Basicity | Conjugate acid pKa ≈ 11.4, higher than triethylamine (≈ 10.6); proton affinity 984 kJ/mol[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC6449804/) |
| Reactivity profile | Strong base but poor nucleophile because of steric hindrance around nitrogen[2](https://www.jove.com/topics/chemistry/diisopropylethylamine-dipea) |
| Typical loadings | 2–3 equivalents in amide couplings; 1.5–2 equivalents as an acid scavenger[5](https://molebench.com/tools/reagents/dipea/) |
| Main hazards | Highly flammable liquid (H225); toxic if inhaled (H331); causes serious eye damage (H318); flash point 9.5 °C[6](https://b2b.sigmaaldrich.com/US/en/product/sigald/496219) |
| Industrial use | Listed for pharmaceuticals manufacture; commercial purity minimum 99%[7](https://www.koeichem.com/en/product/index.php/item?cell003=Amines&cell004=Alkylamines&empty=&id=32&label=1&name=N%2CN-Diisopropylethylamine+++++++++++++++++++++++&order=desc&page=2&sort=cell005) |
## Physical properties
DIPEA is a clear, colorless liquid with a boiling point of 126.5 °C at 760 mmHg, a density of 0.742 at 25 °C, and a vapor pressure of 12.0 mmHg.[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine) Supplier specifications report a specific gravity of 0.756, a boiling point of 128 °C, and a minimum purity of 99% with moisture at most 0.2%.[7](https://www.koeichem.com/en/product/index.php/item?cell003=Amines&cell004=Alkylamines&empty=&id=32&label=1&name=N%2CN-Diisopropylethylamine+++++++++++++++++++++++&order=desc&page=2&sort=cell005) Its computed XLogP3 of 2.2 and topological polar surface area of 3.2 Ų reflect a largely hydrocarbon framework around a single tertiary nitrogen.[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine)
## Basicity and steric hindrance
The usefulness of DIPEA comes from the combination of high basicity and low nucleophilicity. In a comparative study of amine bases, DIPEA and triethylamine both showed reduced nucleophilicity and higher base reactivity than pyridine (pKa ≈ 5.2) because of increasing steric hindrance, with DIPEA the more basic of the two at pKa ≈ 11.4 versus ≈ 10.6 for triethylamine.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC6449804/) The same study reports DIPEA's [proton affinity](https://www.edgepedia.org/proton-affinity) as the highest of the three at 984 kJ/mol, against 972 kJ/mol for triethylamine and 924 kJ/mol for pyridine.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC6449804/) With that high proton affinity, DIPEA acts as a proton scavenger while largely staying out of the reaction itself because its isopropyl groups block approach to nitrogen.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC6449804/) • [2](https://www.jove.com/topics/chemistry/diisopropylethylamine-dipea)
This profile explains its selection in process chemistry. In one industrial screening of bases for a manufacturing step, DIPEA, described as a sterically hindered base, gave the product with the lowest percentage of impurities, and conversion rose from 77.5% to 88.89% when the base choice was optimized.[8](https://jspc-home.com/symposium/symposium_archive/ISPC2015.pdf)
## Applications in synthesis
**Peptide coupling.** DIPEA is a standard base in amide-bond formation, where it deprotonates the amine component and neutralizes the acid generated by coupling reagents such as HATU, HBTU, and EDC.[2](https://www.jove.com/topics/chemistry/diisopropylethylamine-dipea) • [5](https://molebench.com/tools/reagents/dipea/) Typical loadings are 2–3 equivalents in amide couplings and 1.5–2 equivalents as an acid scavenger.[5](https://molebench.com/tools/reagents/dipea/) In solid-phase peptide synthesis it serves as the non-nucleophilic base for Fmoc chemistry, and in Boc chemistry it neutralizes trifluoroacetic acid to release the unprotonated amine after deprotection.[9](https://discovery-pp.ucl.ac.uk/id/eprint/1473766/1/Peter%20Hughes%20Thesis%20Amended%20v2%20Nov%202015.pdf) • [10](https://www.collectionscanada.gc.ca/obj/thesescanada/vol2/QMM/TC-QMM-102984.pdf) Base identity matters for stereochemistry: in a study of macrolactamization of a cyclic tetrapeptide, DIPEA and TMP (conjugate acid pKa around 10–11) were compared with the weaker N-methylmorpholine (pKa 7.38) to see whether base strength affected racemization at the [C-terminus](https://www.edgepedia.org/c-terminus).[11](https://pmc.ncbi.nlm.nih.gov/articles/PMC11311250/)
**Swern oxidation.** In the [Swern oxidation](https://www.edgepedia.org/swern-oxidation) of alcohols to aldehydes and ketones, the final deprotonation step is carried out with a tertiary amine. Bulkier amines such as DIPEA can replace triethylamine when epimerization of the α-center is a concern.[12](https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_%28Organic_Chemistry%29/Reactions/Named_Reactions/Swern_oxidation) A comparative study found that Swern oxidation with triethylamine is effective only with the most robust N-protected α-amino aldehydes and causes a high degree of racemization with epimerization-prone substrates, while DIPEA produces less racemization, though the oxidation rate can be unacceptably slow and products of high enantiomeric excess are not always obtained.[13](https://electronicsandbooks.com/edt/manual/Magazine/T/Tetrahedron%20Letters%20UK/2000/Issue_09/1359.PDF)
**Other transformations.** Supplier application notes list DIPEA as a base in palladium(0)-catalyzed alkoxy carbonylation of allyl phosphates and acetates, in selective enolate formation with boryl triflates, and in nickel-catalyzed C–N coupling of aryl halides with nitroarenes.[6](https://b2b.sigmaaldrich.com/US/en/product/sigald/496219) In a 2025 study of stereospecific [nucleophilic substitution of alcohols](https://www.edgepedia.org/nucleophilic-substitution-of-alcohols) with amines, base screening identified DIPEA as the ideal additive: it trapped the triflic acid formed in the reaction and raised conversion, giving the desired mono-alkylated amine in 85% NMR yield, 83% isolated yield, and 100% enantiospecificity with complete inversion of configuration.[14](https://onlinelibrary.wiley.com/doi/10.1002/anie.202420312) In pharmaceutical process development, switching a reaction to DIPEA made it instantaneous, improved the yield to 87%, and eliminated brown-colored impurities.[15](https://pharmainfonepal.com/wp-content/uploads/2021/01/Encyclopedia-of-Pharmaceutical-Technology-Volume-20.pdf)
## Safety
DIPEA is classified under GHS as a highly flammable liquid and vapor (H225), harmful if swallowed (H302), causing serious eye damage (H318), toxic if inhaled (H331), and may cause respiratory irritation (H335); the signal word is Danger.[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine) Supplier data add Aquatic Chronic 2 (H411) and give a flash point of 9.5 °C with a storage class of flammable liquids.[6](https://b2b.sigmaaldrich.com/US/en/product/sigald/496219) The Koei Chemical specification sheet reports a flash point of 10 °C.[7](https://www.koeichem.com/en/product/index.php/item?cell003=Amines&cell004=Alkylamines&empty=&id=32&label=1&name=N%2CN-Diisopropylethylamine+++++++++++++++++++++++&order=desc&page=2&sort=cell005) Recommended storage is a tightly sealed container in a cool, dry, well-ventilated area away from ignition sources and incompatible substances such as acids and oxidizers.[16](https://www.sinochem-nanjing.com/products/hazardous-chemicals/n-n-diisopropylethylamine-cas-7087-68-5.html) The substance is listed on the EPA Chemical Data Reporting system and on chemical inventories including AICIS, TSCA, ECHA, and the FDA Global Substance Registration System.[1](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine)
## References
1. [Diisopropylethylamine, CID 81531, PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/N%2CN-Diisopropylethylamine)
2. [Diisopropylethylamine (DIPEA), JoVE Chemistry Topics](https://www.jove.com/topics/chemistry/diisopropylethylamine-dipea)
3. [Diisopropylethylamine, NIST Chemistry WebBook](https://webbook.nist.gov/cgi/cbook.cgi?ID=7087-68-5&Units=SI)
4. [Inline Reaction Monitoring of Amine-Catalyzed Acetylation of Benzyl Alcohol, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC6449804/)
5. [DIPEA reagent guide, MoleBench](https://molebench.com/tools/reagents/dipea/)
6. [N,N-Diisopropylethylamine 99.5%, biotech grade, Sigma-Aldrich](https://b2b.sigmaaldrich.com/US/en/product/sigald/496219)
7. [N,N-Diisopropylethylamine product specification, Koei Chemical](https://www.koeichem.com/en/product/index.php/item?cell003=Amines&cell004=Alkylamines&empty=&id=32&label=1&name=N%2CN-Diisopropylethylamine+++++++++++++++++++++++&order=desc&page=2&sort=cell005)
8. [ISPC 2015 symposium proceedings, base screening and kinetic modeling](https://jspc-home.com/symposium/symposium_archive/ISPC2015.pdf)
9. [Peter Hughes PhD thesis, University College London, Fmoc SPPS](https://discovery-pp.ucl.ac.uk/id/eprint/1473766/1/Peter%20Hughes%20Thesis%20Amended%20v2%20Nov%202015.pdf)
10. [Functionalized Ionic Liquid-Supported Organic Synthesis, Library and Archives Canada](https://www.collectionscanada.gc.ca/obj/thesescanada/vol2/QMM/TC-QMM-102984.pdf)
11. [Diastereoselective synthesis of cyclic tetrapeptide pseudoxylallemycin A, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC11311250/)
12. [Swern oxidation, Chemistry LibreTexts](https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_%28Organic_Chemistry%29/Reactions/Named_Reactions/Swern_oxidation)
13. [Synthesis of highly epimerizable N-protected α-amino aldehydes, Tetrahedron Letters](https://electronicsandbooks.com/edt/manual/Magazine/T/Tetrahedron%20Letters%20UK/2000/Issue_09/1359.PDF)
14. [Universal Reagent for Mild and Stereospecific Nucleophilic Substitution of Alcohols with Amines, Angewandte Chemie](https://onlinelibrary.wiley.com/doi/10.1002/anie.202420312)
15. [Encyclopedia of Pharmaceutical Technology, Volume 20](https://pharmainfonepal.com/wp-content/uploads/2021/01/Encyclopedia-of-Pharmaceutical-Technology-Volume-20.pdf)
16. [N,N-Diisopropylethylamine product page, Sinochem Nanjing](https://www.sinochem-nanjing.com/products/hazardous-chemicals/n-n-diisopropylethylamine-cas-7087-68-5.html)
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*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Amines and nitrogen functional groups › Aliphatic amines and polyamines › Aliphatic amines overview*
*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license