DL-valine (516-06-3) Physical and Chemical Properties
DL-valine
Racemic DL-valine is a branched-chain amino acid supplied as a white crystalline powder, used by manufacturers and laboratories as a reagent, formulation component and analytical reference material.
| CAS Number | 516-06-3 |
| Family | Branched-chain amino acids |
| Typical Form | Powder or crystalline solid |
| Common Grades | EP, Reagent Grade |
DL-valine is a racemic alpha-amino acid of the branched-chain amino acid (BCAA) structural class. Chemically it is an alpha-amino carboxylic acid with a secondary (isopropyl) substituent on the beta-carbon; the DL designation denotes a 1:1 mixture of enantiomers at the alpha stereocenter. The molecule contains a primary amine and a carboxylic acid functional group attached to the same carbon (the alpha carbon), which imparts amphoteric behaviour and a strong tendency to adopt a zwitterionic form in condensed phases near neutral \(\mathrm{pH}\). The isopropyl side chain is nonpolar and sterically compact, classifying valine as one of the hydrophobic proteinogenic amino acids at the side-chain level, while the backbone functionality drives hydrophilicity and extensive hydrogen-bonding.
Electronically the molecule has one basic center (the alpha-amino group) and one acidic center (the alpha-carboxyl), leading to internal charge separation in the zwitterion; the topological polar surface area (TPSA) of \(63.3\) and calculated XLogP of \(-2.3\) indicate an overall hydrophilic, hydrogen-bonding-capable small molecule with low intrinsic lipophilicity despite the nonpolar side chain. In industrial and biochemical contexts DL-valine is handled and formulated as a crystalline solid and is used primarily as a nutrient supplement, flavoring agent and as a general-purpose amino acid reagent in biochemical and formulation work.
Common commercial grades reported for this substance include: EP, Reagent Grade.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Melting Point
No experimentally established value for this property is available in the current data context.
Boiling Point
No experimentally established value for this property is available in the current data context.
Vapor Pressure
No experimentally established value for this property is available in the current data context.
Flash Point
No experimentally established value for this property is available in the current data context.
Chemical Properties
Solubility and Phase Behavior
DL-valine is a crystalline, odorless solid reported as soluble in water and essentially insoluble in nonpolar organic solvents such as diethyl ether and poorly soluble in ethanol. The amphoteric nature of the alpha-amino and alpha-carboxyl groups produces strong water solvation through ion–dipole and hydrogen-bonding interactions; in aqueous media the compound predominantly exists as a zwitterion at near-neutral \(\mathrm{pH}\), which explains the high aqueous solubility and low distribution into organic phases. Solubility will be \(\mathrm{pH}\)-dependent due to protonation/deprotonation of the amino and carboxyl functions: increased solubility in strongly acidic or basic media may result from net ionic charge.
Reactivity and Stability
As a simple amino acid, DL-valine exhibits the expected, well-understood reactivity of alpha-amino carboxylic acids. The carboxyl group can be activated or esterified under standard organic chemistry conditions; the amino group will undergo acylation and Schiff-base formation under appropriate conditions. Under strong dehydrating or highly acidic conditions, decarboxylation or dehydration reactions may occur; under strongly oxidizing conditions oxidative deamination is plausible. The racemic DL mixture contains one stereocenter that is not enantiomerically defined; it will not display optical activity but can participate in stereospecific chemistry once resolved. Under normal ambient storage and handling conditions DL-valine is chemically stable as a dry crystalline solid; as with other amino acids, prolonged exposure to moisture, heat or contaminants may lead to slow degradation or microbial growth in aqueous solutions unless properly preserved.
Thermodynamic Data
Standard Enthalpies and Heat Capacity
No experimentally established value for this property is available in the current data context.
Molecular Parameters
Molecular Weight and Formula
- Molecular formula: C5H11NO2
- Molecular weight: \(117.15\,\mathrm{g}\,\mathrm{mol}^{-1}\)
- Exact / monoisotopic mass: 117.078978594
These values correspond to the DL (racemic) composition of the amino acid without additional counterions or salts.
LogP and Polarity
- XLogP: \(-2.3\)
- Topological polar surface area (TPSA): 63.3
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 3
The negative XLogP and moderate TPSA indicate a hydrophilic molecule that preferentially partitions into aqueous phases. The presence of two hydrogen-bond donors (the protonated amine and carboxyl OH in the neutral form) and three acceptors supports extensive aqueous hydrogen bonding and solvation.
Structural Features
- SMILES: CC(C)C(C(=O)O)N
- InChI: InChI=1S/C5H11NO2/c1-3(2)4(6)5(7)8/h3-4H,6H2,1-2H3,(H,7,8)
- InChIKey: KZSNJWFQEVHDMF-UHFFFAOYSA-N
Structural summary: an alpha-amino acid backbone (alpha-carbon bearing both amine and carboxyl functionalities) with a branched isopropyl side chain at the beta position. The DL form contains a single undefined stereocenter (racemic mixture); conformational flexibility is limited by the small size but permits hydrogen-bonded networks in the solid state and solvation shells in aqueous solution.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS Registry Number: 516-06-3
- EC / EINECS number: 208-220-0
- UNII: 4CA13A832H
- ChEBI ID: CHEBI:27266
- ChEMBL ID: CHEMBL11257
- InChIKey: KZSNJWFQEVHDMF-UHFFFAOYSA-N
- SMILES: CC(C)C(C(=O)O)N
Synonyms and Structural Names
Reported synonyms appearing in chemical nomenclature lists include: DL-Valine; 2-Amino-3-methylbutanoic acid; Valine, DL-; H-DL-Val-OH; 2Aminoisovaleric acid, DL; alpha-Aminoisovaleric acid, DL-; (RS)-valine; DL-Val.
Industrial and Commercial Applications
Representative Uses and Industry Sectors
DL-valine is used as a flavoring agent, nutrient supplement and as an ingredient in food and feed formulations where branched-chain amino acids are required. It is employed in nutritional supplements and specialized formulations that aim to deliver BCAA blends. In laboratory and manufacturing contexts it is used as a raw material and reagent for biochemical assays, media formulation and as a building block in small-scale peptide and amino-acid derivative synthesis.
Evaluations for use as a flavouring/nutrient indicate no safety concern at typical intake levels for that application; the substance is generally reported as not meeting hazard-classification criteria under standard hazard classification schemes when supplied in pure form, although product formulations and impurities can alter hazard profiles.
Role in Synthesis or Formulations
DL-valine serves as a feedstock amino acid in pharmaceutical and biochemical production (e.g., for peptide synthesis, formulation of culture media and dietary supplements). It is compatible with standard amino-acid derivatization chemistry (esterification, amide coupling, N-acylation). Reported commercial grades: EP, Reagent Grade.
If used in product development, selection of grade (pharmaceutical, reagent, EP, technical) should be driven by the intended use, impurity-acceptance criteria and regulatory requirements for the final application.
Safety and Handling Overview
Acute and Occupational Toxicity
DL-valine is an essential amino acid and is generally of low acute toxicity in typical exposure scenarios; it is absorbed from the small intestine via active transport. Toxicological summaries for branched-chain amino acids highlight their nutritional importance and metabolic roles; adverse effects are rare at normal intake levels but overexposure or metabolic disorders (e.g., defects in branched-chain amino acid catabolism) can lead to clinical complications. Product-specific materials note that the solid may cause mild irritation to skin, eyes or respiratory tract if inhaled or handled as dust; reported classification samples indicate "Not Classified" under standard hazard criteria for the pure substance.
Occupational controls should follow standard good-practice measures for handling powders: minimize dust generation, provide local exhaust ventilation where appropriate, and use personal protective equipment (gloves, eye protection) to avoid direct contact.
Storage and Handling Considerations
Store DL-valine in a tightly closed container, in a cool, dry, well-ventilated area away from strong oxidizers and moisture. As a hygroscopic crystalline amino acid, it should be protected from prolonged exposure to humidity to prevent caking and microbial contamination in aqueous concentrates. For laboratory and industrial handling, use appropriate PPE, avoid inhalation of dust, and implement spill-control measures for solids. For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and applicable local legislation.
