DL-lactic acid
Enable an agent to identify DL-lactic acid, assess its stereochemical composition and material condition, and determine whether a documented batch is suitable for an intended use.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to identify DL-lactic acid, assess its stereochemical composition and material condition, and determine whether a documented batch is suitable for an intended use.
DL-lactic acid is the racemic form of 2-hydroxypropanoic acid, C3H6O3, containing equal molar amounts of its D and L enantiomers.
It can be Verify a batch's chemical identity and racemic composition against an explicit acceptance specification.; Calculate mass or dilution requirements from a documented assay, water content and concentration basis.; Select or reject a batch for an application using stereochemical, impurity and grade requirements.; Determine sampling, transfer and storage conditions from measured material properties and the applicable SDS.; Assess suitability as a feedstock for neutralization, esterification or polymer production while linking resulting substances to their own models..
Distinguishing features
Require evidence of an approximately equimolar D:L mixture under a declared acceptance tolerance; the DL designation refers to racemic composition. [Sigma-Aldrich product information](https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/208/625/l1250pis.pdf)
Match the 2-hydroxypropanoic-acid structure, rather than relying on molecular formula alone. Lactic acid has formula C3H6O3 and molar mass 90.08 g/mol. [PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/Lactic-Acid)
Distinguish the free acid from a lactate salt or ester through structural identification and counterion or functional-group analysis.
Do not treat a lactic-acid identifier as proof of racemic composition: PubChem CID 612 groups lactic-acid names, including DL-lactic acid. [PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/Lactic-Acid)
Distinguish neat material from aqueous supply forms using measured water content and assay basis; an identified commercial DL-lactic-acid product is approximately 85% by mass in solution. [Sigma-Aldrich product information](https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/208/625/l1250pis.pdf)
Scope
+ Racemic identity and measured D:L composition
+ Free-acid assay, water content, impurities and any condensed lactic-acid species
+ Physical state and properties under stated temperature, pressure and concentration
+ Batch provenance, analytical evidence and grade qualification
+ Concentration-specific hazards and jurisdiction-specific identity and use requirements
- Enantiopure D-lactic acid and L-lactic acid as independently specified substances
- Lactate salts, lactate esters, lactide and polylactic acid as separate substances
- Manufacturing plants and synthesis or fermentation process models
- Finished foods, cosmetics, medicines and other formulations containing lactic acid
- Physiological lactate metabolism and clinical diagnosis or treatment
Characteristics
- Chemical identity and identifier scope
- Registry vr.tr.dl-lactic-acid; candidate external mappings CAS 50-21-5 and PubChem CID 612, with stereochemical scope recorded Supports record matching without treating a broad identifier as a batch stereochemical certificate. [PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/Lactic-Acid)
- Enantiomeric composition
- D and L mole fractions; D:L ratio; enantiomeric excess in %, with method and uncertainty Determines whether the material meets the declared racemic specification.
- Lactic-acid assay
- % by mass, specifying free monomer or total lactic-acid equivalents and as-received or dry basis Makes concentration, purity and dosing calculations interpretable.
- Water content
- % by mass, with analytical method Separates aqueous concentration from chemical purity and qualifies physical-property comparisons.
- Condensed species and impurity profile
- Mass fractions or mg/kg by identified species; detection limits and unknown fraction Tests whether the batch contains species that alter monomer availability or application suitability.
- Acidity and neutralization state
- pH at stated dilution and temperature; titratable acidity in mmol/g; counterion content Distinguishes solution acidity from assay and detects partial conversion to lactate salts.
- Physical state
- Liquid, crystalline, partially crystalline or multiphase, with temperature and composition Informs sampling, transfer and interpretation of apparent batch changes.
- Density and viscosity
- Density in g/mL; dynamic viscosity in mPa·s; temperature and concentration required Supports volume-to-mass conversion and transfer planning for the actual material.
- Thermal behavior
- Melting or freezing range and boiling or decomposition observations in °C; pressure in kPa Prevents values for different solution strengths or pressures from being treated as interchangeable.
- Grade qualification
- Technical, reagent, food, pharmaceutical or other documented specification; qualified, unqualified or unknown for intended use A substance name alone cannot establish suitability for a regulated or stereochemically sensitive application.
- Applicable hazard and exposure record
- Current SDS, GHS categories and statements, jurisdiction, concentration and applicable exposure limits with units Connects handling decisions to evidence for the supplied material.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 30 questions.
Racemic identity Establish what makes this entry DL-lactic acid rather than unspecified or enantiopure lactic acid.
The defining distinction is stereochemical composition, which a name or broad chemical identifier cannot independently verify.
Chemical identity
Resolve structural identity and external identifier boundaries.
Structure and identifier match
Require evidence linking the registry entry to the free-acid structure and explain what each identifier covers.
- Which structural evidence identifies 2-hydroxypropanoic acid and excludes lactate salts, esters and positional isomers? definition
- Which CAS, PubChem and EC records apply, and do they specify racemic material or leave stereochemistry unspecified? boundary
Racemate verification
Turn the DL designation into a testable composition requirement.
D:L balance
Record enantiomer-specific analytical results and the tolerance used to accept a batch as racemic.
- What D:L ratio and measurement uncertainty does a validated chiral assay report? measurement
- What permitted deviation from a 1:1 ratio defines acceptance, and how is a batch outside that tolerance classified? boundary
- If optical rotation is offered as evidence, what confirms chemical identity and enantiomer composition independently? provenance
Composition and assay Describe what a supplied quantity contains and what its reported concentration actually measures.
Water, assay conventions and nonmonomeric species can make nominally similar DL-lactic-acid batches behave differently.
Acid and water balance
Separate chemical purity from aqueous concentration.
Interpretable acid content
Require a defined assay basis and an independently interpretable water result.
- Does the assay quantify free lactic-acid monomer, titratable acidity or total lactic-acid equivalents after a specified pretreatment? definition
- What are the acid and water mass fractions on an as-received basis, and how were they measured? measurement
Secondary species
Identify constituents that an overall acidity result could conceal.
Impurities and condensation products
Investigate salts, residual feedstock contaminants and condensed species without assuming their presence or amount.
- Which methods distinguish monomer from any oligomers or other condensation products, and what amounts are detected? measurement
- Which counterions, residual solvents, metals or organic impurities require limits for the intended use? action
Physical and chemical state Qualify property measurements by the composition and conditions of the actual material.
Aqueous supply forms and differing measurement conditions prevent a single unqualified property list from guiding operations reliably.
Phase and flow
Connect observable state and transport properties to sampling and transfer.
Conditioned physical properties
Record phase, density and viscosity for a stated temperature and composition.
- What phase, density and viscosity are measured at the intended sampling or transfer temperature and acid concentration? measurement
- Does crystallization or phase separation require a validated homogenization procedure before sampling? action
Acidity and thermal response
Keep acid-base measurements and thermal observations tied to their experimental conditions.
Qualified acidity and transition data
Avoid treating pH as concentration or a reduced-pressure boiling value as an atmospheric constant; one supplier reports 122 °C at 15 mmHg. [Sigma-Aldrich](https://www.sigmaaldrich.com/GL/en/product/sial/69785)
- At what dilution, temperature and ionic conditions were pH or dissociation measurements obtained? measurement
- For each melting, freezing or boiling value, what composition, pressure and evidence of decomposition or reaction accompany it? measurement
Grade and use fitness Determine whether evidence for a particular batch supports a particular application.
Racemic identity alone does not establish analytical quality, regulated-use eligibility or suitability for stereochemically sensitive synthesis.
Batch evidence
Tie claimed composition and grade to traceable analytical documentation.
Certificate and specification
Separate measured lot results from catalogue claims and identify the governing specification.
- Which lot-specific certificate supports assay, D:L ratio, water content and impurity claims? provenance
- Which specification and edition define the claimed grade, and which required tests remain unverified? boundary
Application acceptance
Translate the intended use into explicit material acceptance criteria.
Racemate suitability
Require the receiving application to state whether it accepts a racemic input and the measured composition.
- Does the intended application permit racemic lactic acid, or does it require a specified enantiomeric composition? boundary
- What assay, water and impurity limits must the batch meet before dilution, neutralization, esterification or polymer-feedstock use? action
Hazards and material stewardship Connect handling, storage and disposition decisions to the actual concentration, grade and jurisdiction.
A hazard classification for one DL-lactic-acid supply form cannot establish requirements for every concentration or use.
Applicable hazard record
Identify the safety evidence that covers the material in hand.
Concentration-specific classification
Capture classifications from the applicable record; a supplier's approximately 90% product lists Skin Corr. 1C and Eye Dam. 1, illustrating why concentration and product context must accompany the classification. [Sigma-Aldrich](https://www.sigmaaldrich.com/GL/en/product/sial/69785)
- Which current SDS and jurisdiction cover this concentration and impurity profile, and what GHS classifications do they assign? provenance
- Which occupational exposure limits apply to the planned operation, in what units and averaging periods, and where is applicability unresolved? boundary
Storage and disposition
Preserve qualified material condition and determine how changed or unusable material is handled.
Condition preservation and release
Require evidence for container compatibility, storage conditions, retesting and disposal routes.
- Which container materials, storage temperatures and segregation requirements are supported for this acid concentration? action
- Which changes in appearance, water content, assay or impurity profile trigger retesting or rejection? action
- Which transport and waste requirements apply to the actual supplied or spent mixture in the relevant jurisdiction? boundary
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This is a recall-based description; no sources were consulted.
- Check exact CAS, PubChem and EC identifiers against records that explicitly distinguish racemic from unspecified lactic acid.
- Verify melting and boiling behaviour, exposure limits and formal hazard classifications for the actual purity, water content and jurisdiction.
- Which of these check these first hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Anhydrous DL-lactic acid
- Aqueous DL-lactic acid solutions
- Food-grade DL-lactic acid
- Reagent-grade DL-lactic acid
- Which of these kinds and varieties hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- IUPAC nomenclature - rac-2-hydroxypropanoic acid - The racemic designation distinguishes DL-lactic acid from either individual enantiomer.
- Molecular formula - C3H6O3 - Shared by both enantiomers; the formula alone does not identify the racemate.
- CAS Registry Number - Digits in three hyphen-separated groups, with a final check digit - Verify the registry record's stereochemical scope before assigning a number to DL-lactic acid.
- Which of these identifiers and schemes hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Acidulant and pH adjustment in formulations where the applicable grade and stereochemical composition are acceptable.
- Starting material for lactate salts and esters.
- Feedstock for racemic lactide and poly(D,L-lactic acid).
- Laboratory reagent for studying reactions and separation of lactic acid enantiomers.
- Which of these real-world use hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Molar mass - 90.08 - g/mol
- Acid dissociation constant, pKa - Approximately 3.86 in dilute aqueous solution near 25 °C - dimensionless
- Enantiomeric composition - 50:50 D:L for the ideal racemate - molar ratio
- Which of these typical measurements hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Concentrated material can cause serious eye injury and skin damage; severity depends on concentration and formulation.
- Mist exposure can irritate the respiratory tract.
- Water content and self-esterification can change the composition and analytical behaviour of concentrated material.
- Using a racemic feedstock where an enantiopure feedstock is required can change polymer crystallinity and thermal properties.
- Which of these failure modes and hazards hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Permitted food uses, purity requirements and labelling depend on jurisdiction and application.
- Hazard classification and safety-data-sheet wording should be checked for the supplied concentration under the applicable national system.
- Which of these regional variation hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Lactic acid - The broader name can leave stereochemistry unspecified; DL-lactic acid specifically denotes the racemate.
- L-lactic acid - The L enantiomer is stereochemically distinct from an equal D/L mixture.
- D-lactic acid - The D enantiomer is stereochemically distinct from an equal D/L mixture.
- Lactate - Lactate is the conjugate-base anion; lactic acid is the protonated carboxylic acid.
- Lactide - Lactide is a cyclic diester formed from two lactic acid units.
- Poly(D,L-lactic acid) - The polymer contains covalently linked lactyl repeating units rather than free lactic acid molecules.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of DL-lactic acid this model covers, and on what evidence? provenance
What the second pass must settle
- What analytical tolerance should this registry use for racemic composition, and should measurably nonracemic batches remain linked as off-specification instances?
- Which authoritative EC and other regulatory records distinguish racemic lactic acid from stereochemically unspecified lactic acid, and is an existing world model authoritative for this concept?
- Which validated assays distinguish free monomer, total lactic-acid equivalents and condensed species across commercial concentrations?
- Which reliable thermal and transport-property datasets apply separately to neat racemic material and defined aqueous concentrations?
- Which current jurisdiction-specific exposure limits, hazard classifications and food or pharmaceutical specifications apply to the intended grades and uses?