Chemistry:Alkanolamine

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In organic chemistry, alkanolamines (amino alcohols) are organic compounds that contain both hydroxyl (–OH) and amino (–NH
2
, –NHR, and –NR
2
) functional groups on an alkane backbone. Alkanolamine's bifunctionality and physicochemical characteristics lead to its use in many applications, such as textiles, cosmetics, agricultural chemical intermediates, drugs, and metal working fluids.[1][2] Alkanolamines are present in many approved drugs and thousands of natural products.[3] Two amino acids are alkanolamines, formally speaking: serine and hydroxyproline.

  • Tropane alkaloids such as

Alkanolamines usually have high-solubility in water due to the hydrogen bonding ability of both the hydroxyl group and the amino group.[4] Alkanoamines have also shown a broad toxicity for a variety of organisms, including parasites, insect larvae and eggs, and microbes. Studies have also shown that the antimicrobial effect of alkanolamines increases in higher pH's.[5] Most alkanolamines are colorless.[6]

1-Aminoalcohols

1-Aminoalcohols are better known as hemiaminals. Methanolamine is the simplest member. 1-Aminoalcohols tend to be labile, readily converting to more highly condensed derivatives or hydrolyzing to the amine and carbonyl.

2-Aminoalcohols

Routes

2-Aminoalcohols are often generated by the reaction of amines with epoxides:[7]

C
2
H
4
O + R–NH
2
→ RNHC
2
H
4
OH

Hydrogenation or reduction of amino acids gives a large family of chiral 2-aminoalcohols:

RCH(NH
2
)CO
2
H + 2 H
2
→ RCH(NH
2
)CH
2
OH + H
2
O

Examples include prolinol (from proline), valinol (from valine), tyrosinol (from tyrosine). Some 2-aminoalcohols are produced by the Sharpless asymmetric amino hydroxylation.[8][9]

Uses and examples

Simple alkanolamines are used as solvents, synthetic intermediates, and high-boiling bases.[6]

2-Aminoalcohols have been used as synthetic building blocks and chiral auxiliaries.Amino ethanols have been proven to be vital precursors for chiral morpholines and piperazines.[3][10] Key members: ethanolamine, dimethylethanolamine, N-methylethanolamine, Aminomethyl propanol. Two popular drugs, often called alkanolamine beta blockers, are members of this structural class: propranolol, pindolol.[11][12][13] 2-Aminoalcohols can also be found in the direct action subgroup of adrenergic drugs such as epinephrine, isoproterenol, phenylephrine and isoetarine.[14]

Other medicinally useful derivative of ethanolamine: Isoetarine, veratridine, veratrine, epinephrine (adrenaline), norepinephrine (noradrenaline), atropine.

1,3- to 1,7-amino alcohols

Two examples of longer aminoalcohols include Heptaminol, a cardiac stimulant, and propanolamines.

1,3-Aminoalcohols are present in several bioactive molecules, such as Sedinone, Dumetorine, and Hygroline.[15] 1,3-Aminoalcohols have be synthesize through a couple methods. Similar to 2-aminoalcohols, 1,3 aminoalcohols can be formed through ring openings, such as an azo-ring opening and addition.[15] 1,3-aminoalcohols can also be synthesized through an azo-aldol condensation or an intermolecular C-H activation.[15]

1,4 and 1,5-aminoalcohols have been synthesized through the reduction of cyclic amides.[16] Catalyzed alkylation of primary amines with 1,4-butanediol is another synthetic route for 1,4-aminoalcohols.[16] Larger amino alcohol (1,5 - and up) synthesis is comparatively underdeveloped. Electrochemical ring-openings can produce 1,3 to 1,7-aminoalcohols.[17]

References

  1. Davis, John W.; Carpenter, Constance L. (1997), Ware, George W., ed., "Environmental Assessment of the Alkanolamines", Reviews of Environmental Contamination and Toxicology (New York, NY: Springer New York) 149: 87–137, doi:10.1007/978-1-4612-2272-9_2, ISBN 978-1-4612-7482-7, PMID 8956559, https://link.springer.com/chapter/10.1007/978-1-4612-2272-9_2, retrieved 2025-03-19 
  2. Laskar, Ranjini; Dutta, Subhabrata; Spies, Jan C.; Mukherjee, Poulami; Rentería-Gómez, Ángel; Thielemann, Rebecca E.; Daniliuc, Constantin G.; Gutierrez, Osvaldo et al. (2024-04-17). "γ-Amino Alcohols via Energy Transfer Enabled Brook Rearrangement" (in en). Journal of the American Chemical Society 146 (15): 10899–10907. doi:10.1021/jacs.4c01667. ISSN 0002-7863. PMID 38569596. Bibcode2024JAChS.14610899L. 
  3. 3.0 3.1 Sun, Jiawei; Wang, Shuanghu; Harper, Kaid C.; Kawamata, Yu; Baran, Phil S. (January 2025). "Stereoselective amino alcohol synthesis via chemoselective electrocatalytic radical cross-couplings" (in en). Nature Chemistry 17 (1): 44–53. doi:10.1038/s41557-024-01695-7. ISSN 1755-4349. PMID 39754013. Bibcode2025NatCh..17...44S. https://www.nature.com/articles/s41557-024-01695-7. 
  4. "Amino Alcohols - Alfa Chemistry". https://www.alfa-chemistry.com/products/amino-alcohols-94.htm#:~:text=Most%20amino%20alcohols%20are%20highly,at%20normal%20temperature%20and%20pressure.. 
  5. Sandin, M; Allenmark, S; Edebo, L (March 1990). "Selective toxicity of alkanolamines" (in en). Antimicrobial Agents and Chemotherapy 34 (3): 491–493. doi:10.1128/AAC.34.3.491. ISSN 0066-4804. PMID 2334165. 
  6. 6.0 6.1 Martin Ernst; Johann-Peter Melder; Franz Ingo Berger; Christian Koch (2022). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a10_001.pub2. 
  7. Yan, Xu; Feng, Wei; Ng, Jiong Xu; Li, Jiaxin; Liu, Ying; Zhang, Bo; Shao, Pan-Lin; Zhao, Yu (2025). "Recent advances in catalytic enantioselective synthesis of vicinal amino alcohols". Chemical Society Reviews 54 (17): 7966–8018. doi:10.1039/D4CS00966E. PMID 40711534. 
  8. Bodkin, Jennifer A.; McLeod, Malcolm D. (2002). "The Sharpless asymmetric aminohydroxylation". Journal of the Chemical Society, Perkin Transactions 1 (24): 2733–2746. doi:10.1039/B111276G. 
  9. Herranz, E.; Sharpless, K. B. (1983). "Osmium-Catalyzed Vicinal Oxyamination of Olefins by Chloramine-T: cis-2-(p-Toluenesulfonamido)cyclohexanol and 2-Methyl-3-(p-Toluenesulfonamido)-2-Pentanol". Org. Synth. 61: 85. doi:10.15227/orgsyn.061.0085. 
  10. Ager, David J.; Prakash, Indra; Schaad, David R. (1996-01-01). "1,2-Amino Alcohols and Their Heterocyclic Derivatives as Chiral Auxiliaries in Asymmetric Synthesis" (in en). Chemical Reviews 96 (2): 835–876. doi:10.1021/cr9500038. ISSN 0009-2665. PMID 11848773. Bibcode1996ChRv...96..835A. https://pubs.acs.org/doi/10.1021/cr9500038. 
  11. "Propranolol Monograph for Professionals" (in en). https://www.drugs.com/monograph/propranolol.html. 
  12. "Pindolol Uses, Side Effects & Warnings" (in en). https://www.drugs.com/mtm/pindolol.html. 
  13. Wong, Gavin W. K.; Boyda, Heidi N.; Wright, James M. (2014-11-27). "Blood pressure lowering efficacy of partial agonist beta blocker monotherapy for primary hypertension". The Cochrane Database of Systematic Reviews 2014 (11). doi:10.1002/14651858.CD007450.pub2. ISSN 1469-493X. PMID 25427719. 
  14. Vardanyan, R. S.; Hruby, V. J. (2006-01-01), Vardanyan, R. S.; Hruby, V. J. (eds.), "11 - Adrenergic (Sympathomimetic) Drugs", Synthesis of Essential Drugs, Amsterdam: Elsevier, pp. 143–159, ISBN 978-0-444-52166-8, retrieved 2025-03-28
  15. 15.0 15.1 15.2 Wang, Wei; Hu, Yi; Lin, Ruiqi; Wu, Heng; Tong, Qi; Wang, Liansheng; Xiao, Zufeng; Zhu, Lei (2020). "Progress on the Synthesis of 1,3-Amino Alcohol" (in en). Chinese Journal of Organic Chemistry 40 (5): 1129. doi:10.6023/cjoc201911011. ISSN 0253-2786. http://sioc-journal.cn/Jwk_yjhx/CN/10.6023/cjoc201911011. 
  16. 16.0 16.1 Xiao, Zhen; Li, Juanjuan; Yue, Qiang; Zhang, Qian; Li, Dong (2018). "An efficient and atom-economical route to N -aryl amino alcohols from primary amines" (in en). RSC Advances 8 (60): 34304–34308. doi:10.1039/C8RA07355D. ISSN 2046-2069. PMID 35548644. PMC 9086943. https://xlink.rsc.org/?DOI=C8RA07355D. 
  17. Fang, Xinyue; Hu, Xinwei; Li, Quan-Xin; Ni, Shao-Fei; Ruan, Zhixiong (2025). "Paired Electro-Synthesis of Remote Amino Alcohols with/in H2O" (in en). Angewandte Chemie International Edition 64 (6). doi:10.1002/anie.202418277. ISSN 1521-3773. https://onlinelibrary.wiley.com/doi/10.1002/anie.202418277.