DL-Malate (149-61-1) Physical and Chemical Properties
DL-Malate
DL-Malate is the racemic malate dianion commonly supplied as crystalline salts for use as a buffering component and formulation intermediate in R&D, production and quality control workflows.
| CAS Number | 149-61-1 |
| Family | Carboxylate anions (dicarboxylate / malate) |
| Typical Form | Powder or crystalline salt |
| Common Grades | EP, JP |
DL‑Malate (malate dianion) is an aliphatic C4 dicarboxylate bearing a single secondary alcohol substituent (2‑hydroxybutanedioate). Structurally it is a vicinal hydroxy‑dicarboxylate: two carboxylate groups are attached to a four‑carbon backbone with a hydroxyl on C‑2. Electronic structure is dominated by two carboxylate anions at physiological and basic pH, producing a net formal charge of \(-2\) and a highly polarized anionic framework that engages in strong ionic and hydrogen‑bonding interactions with counterions and solvent molecules.
The dianionic form is strongly hydrophilic with low calculated lipophilicity and a high polar surface area. It functions as the doubly deprotonated conjugate base of malic acid; in solution its chemistry is governed by acid–base equilibria of the carboxyl groups and by coordination/complexation of the carboxylate oxygens and the hydroxyl group to metal cations. As an anionic organic acid derivative it is resistant to simple hydrolysis under neutral aqueous conditions but is susceptible to oxidation and enzymatic transformation in biological systems.
DL‑Malate is widely recognized as a primary metabolic intermediate in central carbon metabolism and is used extensively in biochemical, food‑chemical and industrial contexts where a water‑soluble dicarboxylate is required. Common commercial grades reported for this substance include: EP, JP.
Molecular Parameters
Molecular Weight and Formula
- Molecular formula: C4H4O5-2 (as provided).
- Molecular weight: 132.07 \(\mathrm{g}\,\mathrm{mol}^{-1}\).
- Exact mass (computed): 132.00587322.
- Monoisotopic mass: 132.00587322.
The molecular weight and exact mass correspond to the dianionic form of malate (loss of two protons). In solution, observed mass and analytical behavior depend on counterions and ion‑pairing; salts and hydrated forms will change practical formula weight for handling and formulation.
Charge State and Ion Type
- Formal charge: \(-2\).
DL‑Malate exists as a dianion under neutral to basic aqueous conditions; protonation to the monoanionic and neutral acid forms occurs under progressively acidic conditions. The dianionic nature promotes high aqueous solubility and strong interactions with polyvalent cations (e.g., Ca\(^{2+}\), Mg\(^{2+}\)) which can form insoluble or poorly soluble salts under certain conditions.
LogP and Polarity
- XLogP3‑AA: 0
- Topological polar surface area (TPSA): 100 \(\text{Å}^2\)
The computed XLogP of 0 and a TPSA of 100 \(\text{Å}^2\) indicate very low intrinsic lipophilicity and high polarity. As a dianion, DL‑Malate partitions strongly into aqueous phases and will have minimal partitioning into nonpolar organic solvents in its ionic form; counterion pairing or conversion to the protonated acid increases organic solubility.
Structural Identifiers (SMILES, InChI)
- SMILES: C(C(C(=O)[O-])O)C(=O)[O-]
- InChI: InChI=1S/C4H6O5/c5-2(4(8)9)1-3(6)7/h2,5H,1H2,(H,6,7)(H,8,9)/p-2
- InChIKey: BJEPYKJPYRNKOW-UHFFFAOYSA-L
These identifiers correspond to the canonical connectivity of the malate dianion and are suitable for unambiguous structure exchange and database matching. SMILES and InChI are provided in plain text for chemical informatics use.
Acid–Base Behavior
Conjugate Acid and Speciation
DL‑Malate is the doubly deprotonated conjugate base of malic acid (IUPAC: 2‑hydroxybutanedioic acid). Speciation in aqueous solution is pH‑dependent: the dianion converts to the monoanion and ultimately to the neutral diacid as pH decreases. The hydroxyl substituent at C‑2 is not a primary acid site but can influence acidity by inductive and hydrogen‑bonding effects.
Acid–Base Equilibria and Qualitative pKa Discussion
No experimentally established value for this property is available in the current data context.
(For practical work, users should consult primary experimental literature or product documentation for precise \(\mathrm{p}K_a\) values of the carboxyl groups and use those values when modeling speciation in buffered or formulated systems.)
Chemical Reactivity
Chemical Stability
The malate dianion is chemically stable under neutral to mildly basic aqueous conditions. Stability considerations include: - Resistance to simple hydrolytic cleavage of the carbon backbone under ambient conditions. - Susceptibility to oxidation under strong oxidizing conditions; in biological contexts the hydroxy‑dicarboxylate is readily oxidized or enzymatically transformed. - Potential for salt formation and precipitation with divalent or polyvalent metal cations, which can affect apparent solubility and storage stability.
Thermal decomposition is not typical under standard handling temperatures; formulations and processing should avoid conditions that favor oxidation, dehydration or decarboxylation.
Formation and Hydrolysis Pathways
- Formation: DL‑Malate is formed by deprotonation of both carboxyl groups of malic acid (2‑hydroxybutanedioic acid). In biochemical systems it is produced and consumed enzymatically in central metabolic pathways.
- Hydrolysis: No simple hydrolysis pathway applies to the C–C backbone under mild conditions; the principal transformations are acid–base protonation/deprotonation and redox/enzymatic conversions rather than hydrolytic cleavage.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS number: 149-61-1
- Deprecated CAS: 6204-95-1
- ChEBI: CHEBI:15595
- DSSTox Substance ID: DTXSID00933521
- Nikkaji Number: J209.508D
- Wikidata: Q27098132
- InChIKey: BJEPYKJPYRNKOW-UHFFFAOYSA-L
These registry identifiers and codes are provided as recorded for unambiguous substance identification in procurement, quality control and regulatory contexts.
Synonyms and Structural Names
Selected depositor‑supplied synonyms that appear in the identification data: - DL‑Malate - malate - 2‑hydroxybutanedioate - malate dianion - malate(2-) - Butanedioic acid, 2‑hydroxy‑, ion(2-) - DL‑Apple Acid - Hydroxybutanedioate - DL Malate - Malate ion(2-) - Hydroxysuccinate - malate anion - 3‑hydroxysuccinate - 2‑Hydroxysuccinate - (RS)-malic acid - (RS)-malate - hydroxybutanedioic acid, ion(2-) - hydroxybutanedioic acid
These synonyms reflect alternative structural names, ionic descriptors, and stereochemical notations commonly encountered in specifications and literature.
Industrial and Commercial Applications
Role as Active Ingredient or Intermediate
DL‑Malate primarily functions as a small, water‑soluble organic acid/anion in biochemical and chemical applications. It is a central metabolite in cellular carbon metabolism and is used as a reagent or intermediate in biochemical studies, analytical chemistry, and formulation science where a polar dicarboxylate is required.
Representative Application Contexts
Representative contexts where DL‑Malate or its salts are employed include: - Biochemical research and metabolic assays as a metabolite standard or substrate. - Formulation components in aqueous systems where buffering capacity, chelation, or osmotic control are required. - Raw material for production of salts used in food, pharmaceutical and analytical applications (selection of a specific salt form and grade depends on downstream use and regulatory requirements).
No concise application summary is available in the current data context; in practice this substance is selected based on its general properties described above.
Safety and Handling Overview
Toxicity and Biological Effects
DL‑Malate is an endogenous metabolite and, in common salt forms, exhibits low acute systemic toxicity relative to many organic compounds. Typical hazards are those of an ionic organic acid salt: eye and mucous membrane irritation on contact with concentrated dusts or solutions, and potential gastrointestinal irritation if ingested in large amounts. Occupational exposure controls, appropriate personal protective equipment (gloves, eye protection) and standard industrial hygiene practices are recommended.
For detailed toxicological endpoints, dose metrics and exposure limits, consult product‑specific safety documentation.
Storage and Handling Considerations
- Store in a cool, dry place in tightly closed containers to prevent contamination and uptake of moisture; aqueous solutions should be protected from microbial growth.
- Avoid storage with strong oxidizers and materials incompatible with acidic or anionic salts; control dust generation when handling the powder.
- Use appropriate ventilation, dust control and spill containment measures during transfer and formulation.
- For detailed hazard, transport and regulatory information, users should refer to the product‑specific Safety Data Sheet (SDS) and local legislation.
