L-Aspartic acid

Catalog	BBC56848
CAS	56-84-8
Structure
Description	Aspartic acid (abbreviated as Asp or D; encoded by the codons [GAU and GAC]), also known as aspartate, is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated -NH+ 3 form under biological conditions), an α-carboxylic acid group (which is in the deprotonated -COO- form under biological conditions), and a side chain CH2COOH. Under physiological conditions in proteins the sidechain usually occurs as the negatively charged aspartate form, -COO-. It is semi-essential in humans, meaning the body can synthesize it from oxaloacetate.In proteins aspartate sidechains are often hydrogen bonded, often as asx turns or asx motifs, which often occur at the N-termini of alpha helices.Asp's L-isomer is one of the 23 proteinogenic amino acids, i.e., the building blocks of proteins. Asp (and glutamic acid) is classified as acidic, with a pKa of 3.9, however in a peptide this is highly dependent on the local environment (as with all amino acids), and could be as high as 14. Asp is pervasive in biosynthesis.L-aspartic acid is one of the two main ingredients of the artificial sweetener aspartame, along with L-phenylalanine.
Synonyms	(S)-Butanedioicaci
IUPAC Name	(2S)-2-Aminobutanedioic acid
Molecular Weight	133.1
Molecular Formula	C4H7NO4
Canonical SMILES	C(C(C(=O)O)N)C(=O)O
InChI	InChI=1S/C4H7NO4/c5-2(4(8)9)1-3(6)7/h2H,1,5H2,(H,6,7)(H,8,9)/t2-/m0/s1
InChI Key	CKLJMWTZIZZHCS-REOHCLBHSA-N
Boiling Point	245.59 °C
Melting Point	>300 °C(lit.)
Flash Point	113.5 °C
Purity	98%
Density	1.66 g/cm³
Solubility	Slightly soluble in water, insoluble in ether
Appearance	White powder
Storage	Store below +30 °C
pH	2.5-3.5 (4g/l, H₂O, 20°C)
pKa	1.99(at 25 °C)
Refractive Index	1.66
Solubility in Water	5 g/L

Case Study

L-Aspartic Acid Is Used for the Synthesis of Functional Graphene Quantum Dots

Wu, Chenpu, et al. Desalination 498 (2021): 114811.

L-Aspartic acid (L-Asp) plays a critical role in the synthesis of L-aspartic acid-functionalized graphene quantum dots (AGQDs), which are key nanomaterials used to fabricate high-performance thin-film nanocomposite (TFN) nanofiltration membranes. These membranes exhibit superior desalination and antifouling properties due to the synergistic effects of L-Asp and graphene quantum dots (GQDs).
The AGQDs were prepared via a one-step hydrothermal method, where citric acid (10 g) and L-Asp (5 g) were dissolved in deionized water and subjected to magnetic stirring at 200 °C for 2 hours. During this heating process, L-Asp reacts with citric acid, facilitating the formation of nitrogen-doped carbon-based nanostructures. The gradual color transition to red-orange indicates successful AGQD formation. The product was neutralized with 1 M NaOH, followed by purification through dialysis (1 kDa membrane) and final concentration using rotary evaporation.
The incorporation of AGQDs into the polyamide (PA) selective layer via interfacial polymerization imparts improved hydrophilicity, charge distribution, and structural uniformity to the membrane. These enhancements lead to increased water permeability and salt rejection, while also suppressing membrane fouling.
Thus, L-aspartic acid serves as a multifunctional nitrogen source and molecular modifier, enabling the fabrication of AGQDs for advanced water purification technologies.

L-Aspartic Acid Is Used for the Preparation of a Copper(II)-Based Heterogeneous Catalyst

Mohammadi, Masoud, Arash Ghorbani-Choghamarani, and Noorullah Hussain-Khil. Journal of Physics and Chemistry of Solids 177 (2023): 111300.

L-Aspartic acid (L-Asp) serves as a key building block in the preparation of a novel copper(II) chelate complex anchored on silica-coated nanomagnetic zirconium ferrite (ZrFe₂O₄@SiO₂), aimed at high-performance heterogeneous catalysis. The synthetic strategy leverages both carboxyl groups of L-Asp for metal coordination, while maintaining their reactivity throughout the functionalization process.
Initially, L-Asp was reacted with (3-chloropropyl)trimethoxysilane and potassium carbonate in toluene at 100 °C under nitrogen atmosphere to yield a silane-functionalized aspartic acid ligand (ASP-n-PTMS). This ligand was then immobilized onto ZrFe₂O₄@SiO₂ nanoparticles through reflux in toluene, generating the magnetically separable ZrFe₂O₄@SiO₂-n-Pr-ASP nanostructure.
To form the final catalyst, the nanostructure was treated with Cu(NO₃)₂·3H₂O in ethanol at 80 °C under nitrogen for 24 hours, yielding ZrFe₂O₄@SiO₂-n-Pr-ASP-Cu(II). The resulting complex exhibits strong metal-ligand coordination facilitated by the carboxyl groups of L-Asp, which remain intact during silanization.
This approach not only highlights the chelating ability of L-aspartic acid but also demonstrates its utility in fabricating robust, recyclable, and magnetically separable catalysts for green and sustainable chemical processes. The magnetic core enables easy recovery, making the system ideal for repeated catalytic applications.

L-Aspartic Acid for Electrostatic Adsorption on rGO-LDH Nanohybrids

Su, Yue, et al. Journal of Water Process Engineering 71 (2025): 107228.

L-Aspartic acid (L-Asp) plays a crucial role in the preparation of a multifunctional hybrid nanomaterial, where it is electrostatically adsorbed onto reduced graphene oxide-layered double hydroxide (rGO-LDH) nanoparticles. This process results in a stable nanocomposite that exhibits barrier properties, corrosion inhibition, and enhanced compatibility with organic resins.
In this study, L-Asp anions were dissolved in deionized water and added to a dispersion of rGO-LDH. The electrostatic interaction between the L-Asp and LDH allowed for uniform adsorption of the L-Asp anions on the surface of graphene. The final product, rGO-LDH-Asp, demonstrated a loading capacity of 40.5 wt% for L-Asp, highlighting the efficiency of the adsorption process.
Subsequently, rGO-LDH-Asp was incorporated into epoxy resins, forming a nanocomposite coating that exhibited both corrosion inhibition and "corrosion promotion" properties. This unique functionality is attributed to the synergistic effect of the graphene, LDH, and L-Asp interactions, which together provide a protective barrier against corrosion while enhancing the overall performance of the composite material.
The resulting nanocomposite coatings, with a film thickness of approximately 77 μm, exhibit promising applications in the field of corrosion protection for various industrial and engineering materials.