5-Amino-1-pentanol is an amino alcohol with a primary amino group and a primary hydroxy group at the ends of a linear C5-alkanes. As a derivative of the platform chemical furfural (that is easily accessible from pentoses), 5-amino-1-pentanol may become increasingly important in the future as a building block for biodegradable polyesteramides and as a starting material for valerolactam — the monomer for polyamides.
The complete hydrogenation of furfural (furan-2-aldehyde) yields tetrahydrofurfuryl alcohol (2-hydroxymethyltetrahydrofuran), which undergoes ring expansion upon dehydration to give dihydropyran. Dihydropyran reacts with ammonia in a reductive amination under ring opening to produce 5-amino-1-pentanol.
Product yields of up to 85% can be achieved with a continuous process using a nickel-hydrotalcite catalyst.
Similarly, the hemiacetal 2-hydroxytetrahydropyran that is formed from dihydropyran with hydrochloric acid can be converted to 5-amino-1-pentanol by reductive amidation with ammonia and hydrogen upon water elimination.
5-Amino-1-pentanol forms white crystalline clumps at solidification temperatures around 35 °C, which dissolve in water, ethanol, and acetone. The aqueous solution (500 g-l−1) reacts strongly alkaline (pH 13.2 at 20 °C).
Amino alcohols such as 5-amino-1-pentanol have been studied for their suitability of absorption of carbon dioxide.
5-Amino-1-pentanol dehydrates when heated over ytterbium(III) oxide (Yb2O3) to give 4-penten-1-amine (I). Also formed piperidine (II), 2,3,4,5-tetrahydropyridine (III), and 1-pentylamine (IV).
Being bifunctional, 5-amino-1-pentanol reacts in a polycondensation reaction with esters of dicarboxylic acids (or their cyclic acid anhydrides, such as succinic anhydride) to give polyesteramides. These polymers have been investigated as biodegradable plastics, e.g. absorbable sutures.[1] During the reaction, the succinic anhydride reacts initially with the nucleophilic amino group to form an ω-hydroxycarboxylic acid, which is subsequently polycondensed with carbodiimides, such as the hydrochloride of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimides (EDC-HCl).
In a dehydrogenation, catalyzed by rhodium and ruthenium complexes, valerolactam, the δ-lactam of 5-aminopentanoic acid, is formed from 5-amino-1-pentanol in high (94%) yield.
Valerolactam could be of relevance for polyamide 5. Polyamide 5 has garnered little attention so far but is of interest due to its ferroelectricity.