L-Aspartic acid β-methyl ester hydrochloride CAS 16856-13-6 98% white crystalline powder amino acid protecting monomer / peptide synthesis intermediat

1. Product Overview

L-Aspartic acid β-methyl ester hydrochloride (also known as β-Methyl L-aspartate hydrochloride or H-Asp(OMe)-OH·HCl) is a derivative of the natural non-essential amino acid L-aspartic acid, in which the β-carboxyl group is esterified with a methyl group and the α-amino group is protected as a hydrochloride salt. With the molecular formula C₅H₉NO₄·HCl (MW 183.59) and CAS number 16856-13-6, this compound appears as a white to almost white crystalline powder. It is widely used as a key building block in peptide chemistry and fine chemical synthesis, offering controlled selectivity for carboxyl-group protection strategies. The product is supplied at ≥98% purity (HPLC), suitable for research, pharmaceutical intermediate, and custom synthesis applications.

2. Key Features and Advantages

• High chiral purity with defined L-configuration, ensuring stereoselectivity in peptide coupling reactions.

• Selective β-methyl esterification leaves the α-carboxyl free for activation, making it ideal for stepwise aspartic acid incorporation in solid-phase or solution-phase peptide synthesis.

• Hydrochloride salt form enhances stability, water solubility, and ease of handling compared to free base forms.

• Low moisture content and consistent batch-to-batch quality under strict QC (≥98% HPLC, specific optical rotation +13±1.5° [c=1, EtOH/H₂O 1:3]).

• Compatible with standard Fmoc and Boc amino acid protection schemes in combinatorial chemistry.

3. Main Applications

• Peptide synthesis: serves as a mono-protected aspartic acid equivalent for introducing Asp residues with selective side-chain (β-COOH) ester protection during SPPS (solid-phase peptide synthesis) and solution-phase methodologies.

• Pharmaceutical intermediate: used in the preparation of bioactive peptides, aspartic acid-containing drug candidates, and chiral auxiliaries in asymmetric synthesis.

• Biochemical research: employed in studies on protein structure–function relationships, enzymatic reaction mechanisms, and metabolic pathway investigations involving aspartate derivatives.

• Fine chemical manufacturing: acts as an amino acid protecting monomer for custom synthesis of modified peptides, peptidomimetics, and specialty agrochemical or cosmetic intermediates.

4. Technical Specifications

5. Storage and Handling

Store in a cool, dry, well-ventilated area at 2–8 °C; for long-term preservation, keep at −20 °C in a tightly sealed container protected from moisture and light. Keep container tightly closed when not in use to prevent hygroscopic degradation. Avoid exposure to incompatible materials such as strong oxidizers, bases, and reducing agents. Handle in a well-ventilated area using appropriate personal protective equipment (lab coat, nitrile gloves, safety goggles). Minimize dust generation during weighing and transfer; use in a fume hood if aerosol formation is possible. Do not eat, drink, or smoke in handling areas. Wash hands thoroughly after use.

6. Safety Overview

This substance is classified under GHS as Warning (GHS07 pictogram). Hazard statements: H315 (Causes skin irritation), H319 (Causes serious eye irritation), H335 (May cause respiratory irritation). Precautionary statements include P261 (Avoid breathing dust/fume), P264 (Wash skin thoroughly after handling), P271 (Use only outdoors or in well-ventilated area), P280 (Wear protective gloves/eye protection), P305+P351+P338 (IF IN EYES: Rinse cautiously with water for several minutes; remove contact lenses if present and easy to do; continue rinsing). In case of inhalation, move to fresh air; if irritation persists, seek medical attention. For skin contact, wash with plenty of soap and water. For eye contact, irrigate immediately with copious water for at least 15 minutes. Not intended for human or veterinary therapeutic use; for laboratory and industrial research purposes only. WGK Germany: 3. Transport: not classified as dangerous goods under UN model regulations (NONH for all modes). Consult the full SDS before use.