Alkanolamine
Organic compounds with hydroxyl and amino groups on an alkane backbone
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In organic chemistry, alkanolamines (amino alcohols) are organic compounds that contain both hydroxyl (−OH) and amino (−NH2, −NHR, and −NR2) 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
Methanolamine, from the reaction of ammonia with formaldehyde
2-Amino-2-methyl-1-propanol is a precursor to oxazolines
Sphingosine is a component of some cell membranes.
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]
- C2H4O + R−NH2 → RNHC2H4OH
Hydrogenation or reduction of amino acids gives a large family of chiral 2-aminoalcohols:
- RCH(NH2)CO2H + 2 H2 → RCH(NH2)CH2OH + H2O
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]