Download SDS
CAS No.: 99-66-1
Check the VPA (Valproic acid) product page for in-depth specifications, including solubility, stock solutions, MOA, and working concentrations.

Quick Safety Reference

🛡️ Hazard Overview

  • GHS Class: GHS05; GHS07; GHS08
  • Signal Word: Danger
  • Hazard Statements: H302; H315; H318; H319; H335; H336; H360; H362; H370; H372

🧤 PPE Guidelines

  • Gloves: Chemical‑resistant gloves suggested
  • Eye Protection: Safety goggles suggested
  • Respirator: Dust respirator if dust occurs

❄️ Storage

  • Storage Temp: -20°C (-4°F) Keep dry

🚑 Emergency First Aid

  • For inhalation, skin, eye or ingestion exposure, please refer to full SDS Section 4.

GHS 16 Safety Standard Sections

Product identifier

  • Product Name: VPA (Valproic acid)
  • Catalog Number: S3944
  • CAS Number: 99-66-1
  • IUPAC Name: Pentanoic acid, 2-​propyl-

Relevant identified uses and uses advised against

  • Identified uses: For research and development use only; laboratory chemicals; manufacture of substances.
  • Uses advised against: Not for pharmaceutical, household, or other unapproved uses.

Details of the supplier

  • Company: Selleck Chemicals
  • TollFree: +1 877 796-6397
  • Tel: +1 832 582-8158
  • Fax: +1 832 582-8590

Emergency telephone number

  • Emergency phone #: +1 832 582-8158

2.1 GHS classification in accordance with 29 CFR 1910 (OSHA HCS):
Acute toxicity (oral): Category 4. H302
Skin irritation: Category 2. H315
Serious eye damage: Category 1. H318
Serious eye irritation: Category 2. H319
Specific target organ toxicity (single exposure): Category 3. H335
Specific target organ toxicity (single exposure): Category 3. H336
Reproductive toxicity: Category 1. H360
Reproductive toxicity: Category 1B. H362
Specific target organ toxicity (single exposure): Category 1. H370
Specific target organ toxicity (repeated exposure): Category 1. H372

2.2 GHS Label elements, including precautionary statements
Hazard Pictogram(s):
GHS05 GHS07 GHS08
Signal Word:
Danger
Hazard statement(s):
H302: Harmful if swallowed
H315: Causes skin irritation
H318: Causes serious eye damage
H319: Causes serious eye irritation
H335: May cause respiratory irritation
H336: May cause drowsiness or dizziness
H360: May damage fertility or the unborn child
H362: May cause harm to breast-fed children
H370: Causes damage to organs
H372: Causes damage to organs through prolonged or repeated exposure
Precautionary statement(s):
Prevention:
P203: Obtain, read and follow all safety instructions before use.
P260: Do not breathe dust/fume/gas/mist/vapors/spray.
P261: Avoid breathing dust/fume/gas/mist/vapors/spray.
P263: Avoid contact during pregnancy/while nursing.
P264: Wash hands thoroughly after handling.
P264+P265: Wash hands thoroughly after handling. Do not touch eyes.
P270: Do not eat, drink or smoke when using this product.
P271: Use only outdoors or in a well-ventilated area.
P280: Wear protective gloves/protective clothing/eye protection/face protection/hearing protection.
Response:
P301+P317: IF SWALLOWED: Get medical help.
P302+P352: IF ON SKIN: wash with plenty of water.
P304+P340: IF INHALED: Remove person to fresh air and keep comfortable for breathing.
P305+P351: IF IN EYES: Rinse cautiously with water for several minutes.
P305+P354: IF IN EYES: Immediately rinse with water for several minutes.
P308+P316: IF exposed or concerned: Get emergency medical help immediately.
P317: Get emergency medical help.
P318: if exposed or concerned, get medical advice.
P319: Get medical help if you feel unwell.
P321: Specific treatment (see information on this label and safety datasheet)).
P330: Rinse mouth.
P332+P317: If skin irritation occurs: Get medical help.
P337+P317: If eye irritation persists: Get medical help.
P338: Remove contact lenses, if present and easy to do. Continue rinsing.
P362+P364: Take off contaminated clothing and wash it before reuse.
Storage:
P403+P233: Store in a well-ventilated place. Keep container tightly closed.
P405: Store locked up.
Disposal:
P501: P501 Dispose of contents/ container to an approved waste disposal plant.

2.3 Other hazards
None.

3.1 Substances
Product name: VPA (Valproic acid)
CAS Number: 99-66-1
PubChem CID: 3121
Molecular formula: C8H16O2
Molecular weight: 144.21 g/mol
IUPAC name: 2-propylpentanoic acid

3.2 Mixtures
Not applicable (pure substance).

4.1 Description of first aid measures
Inhalation: INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. If symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop, call a physician and be prepared to transport the victim to a hospital. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to t
Skin contact: SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment.
Eye contact: EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.
Ingestion: INGESTION: DO NOT INDUCE VOMITING. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Be prepared to transport the victim to a hospital if advised by a physician. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport

4.2 Most important symptoms and effects, both acute and delayed
See Section 11 (Toxicological Information).

4.3 Indication of any immediate medical attention and special treatment needed
Treat symptomatically. Contact a poison control center or physician for severe exposure.

5.1 Extinguishing media
Suitable: Water spray, dry chemical, carbon dioxide (CO2), alcohol-resistant foam.
Unsuitable: None known.

5.2 Specific hazards arising from the substance or mixture
Fires involving this material can be controlled with a dry chemical, carbon dioxide or Halon extinguisher. (NTP, 1992)

5.3 Advice for firefighters
Wear self-contained breathing apparatus (SCBA) and full protective clothing.
Fight fire from upwind. Cool containers with water spray until fire is extinguished.
Flash point: 232 °F (NTP, 1992)

6.1 Personal precautions, protective equipment and emergency procedures
Wear appropriate personal protective equipment (see Section 8).
Avoid breathing dust/vapor. Ensure adequate ventilation.
Evacuate personnel to safe areas. Keep people away from and upwind of spill.

6.2 Environmental precautions
Prevent product from entering drains, waterways, or soil.
Contain spill with inert absorbent material.

6.3 Methods and materials for containment and cleaning up
SRP: Expired or waste pharmaceuticals shall carefully take into consideration applicable DEA, EPA, and FDA regulations. It is not appropriate to dispose by flushing the pharmaceutical down the toilet or discarding to trash. If possible return the pharmaceutical to the manufacturer for proper disposal being careful to properly label and securely package the material. Alternatively, the waste pharmaceutical shall be labeled, securely packaged and transported by a state licensed medical waste contractor to dispose by burial in a licensed hazardous or toxic waste landfill or incinerator.
SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

7.1 Precautions for safe handling
SMALL SPILLS AND LEAKAGE: If you spill this chemical, FIRST REMOVE ALL SOURCES OF IGNITION. Then, use absorbent paper to pick up all liquid spill material. Your contaminated clothing and absorbent paper should be sealed in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with 60-70% ethanol followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.
STORAGE PRECAUTIONS: You should store this chemical under ambient temperatures, and keep it away from oxidizing materials. (NTP, 1992)
Store between 15 and 30 °C (59 and 86 °F), in a tight container. /Valproic Acid Capsules USP/
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. Store in a tight container. Protect from freezing. /Valproic Acid Syrup USP/

7.2 Conditions for safe storage, including any incompatibilities
Store between 15 and 30 °C (59 and 86 °F), in a tight container. /Valproic Acid Capsules USP/
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. Store in a tight container. Protect from freezing. /Valproic Acid Syrup USP/
Store away from incompatible materials (see Section 10).
[Note: Specific storage temperature not available in public databases. Refer to supplier Certificate of Analysis (COA) for exact storage conditions.]
Store in original container. Keep upright to prevent leakage.

8.1 Exposure controls
8.1.1 Occupational exposure limits (OEL)
OSHA PEL: Not established.
ACGIH TLV: Not established.
NIOSH REL: Not established.
No occupational exposure limit values are established for this substance.
Use the lowest feasible exposure level (ALARA principle).

8.1.2 Appropriate engineering controls
Use only in a chemical fume hood or with local exhaust ventilation.
Ensure adequate ventilation to keep airborne concentrations below exposure limits.

8.2 Individual protection measures
8.2.1 Eye/face protection
Wear chemical safety goggles and face shield.
8.2.2 Skin protection
Wear protective gloves. Recommended material: Nitrile rubber.
Wear suitable protective clothing (lab coat).
8.2.3 Respiratory protection
Use NIOSH-approved dust/mist respirator (N95 or higher) if ventilation is inadequate.
8.2.4 Thermal hazards
Not applicable.

9.1 Information on basic physical and chemical properties
a) Appearance: Valproic acid is a clear colorless liquid. (NTP, 1992)
b) Odor: Characteristic odor
c) Odor threshold: No data available
d) pH: No data available
e) Melting point/freezing point: No data available
f) Initial boiling point and boiling range: 428 °F at 760 mmHg (NTP, 1992)
g) Flash point: 232 °F (NTP, 1992)
h) Evaporation rate: No data available
i) Flammability (solid, gas): No data available
j) Upper/lower flammability or explosive limits: No data available
k) Vapor pressure: No data available
l) Vapor density: No data available
m) Relative density: 0.922 at 32 °F (NTP, 1992) - Less dense than water; will float
n) Water solubility: less than 1 mg/mL at 72 °F (NTP, 1992)
o) Partition coefficient: n-octanol/water: Log P (n-octanol/water): 2.8
p) Auto-ignition temperature: No data available
q) Decomposition temperature: No data available
r) Viscosity: No data available
s) Explosive properties: No data available
t) Oxidizing properties: No data available

9.2 Other information
Topological Polar Surface Area (TPSA): 37.3 Ų
Complexity: 93

10.1 Reactivity
No specific reactivity hazards identified under normal handling conditions.

10.2 Chemical stability
Stable under recommended storage conditions.

10.3 Possibility of hazardous reactions
No hazardous reactions under normal conditions.

10.4 Conditions to avoid
Avoid heat, sparks, open flames, direct sunlight, and moisture.

10.5 Incompatible materials
Strong oxidizing agents, strong acids, strong bases.

10.6 Hazardous decomposition products
Thermal decomposition may produce: Carbon monoxide (CO), Carbon dioxide (CO₂).
See also Section 5 (Fire-fighting measures) for combustion products.

11.1 Information on toxicological effects
Acute toxicity:
No acute toxicity data available.
Skin corrosion/irritation:
Causes skin irritation (H315).
Serious eye damage/eye irritation:
Causes serious eye damage (H318).
Respiratory or skin sensitization:
No data available.
Germ cell mutagenicity:
No data available.
Carcinogenicity:
No data available.
Reproductive toxicity:
May damage fertility or the unborn child (H360).
Specific target organ toxicity (single exposure):
H370, H372
Specific target organ toxicity (repeated exposure):
No data available.
Aspiration hazard:
No data available.

11.2 Additional information
Carcinogen classification:
No indication of carcinogenicity to humans (not listed by IARC).
Exposure routes:
Inhalation.
Rapid absorption from gastrointestinal tract. Although the rate of valproate ion absorption may vary with the formulation administered (liquid, solid, or sprinkle), conditions of use (e.g., fasting or postprandial) and the method of administration (e.g., whether the contents of the capsule are sprinkled on food or the capsule is taken intact), these differences should be of minor clinical importance under the steady state conditions achieved in chronic use in the treatment of epileps
Signs and symptoms of exposure:
Acute toxicity symptoms include hypo/hyperthermia, tachycardia, hepatic toxicity, hypotension, respiratory depression, coma, confusion, somnolence, dizziness, headaches and cerebral edema. Allopecia, anorexia, liver toxicity, renal failure, tremors and miosis are also associated with chronic toxicity.
Data source: Hazardous Substances Data Bank (HSDB) via PubChem.

12.1 Toxicity
EC50; Species: Xenopus laevis (African clawed frog, embryo); Conditions: freshwater, renewal, pH 7.0-7.8; Concentration: 30500 ug/L for 96 hr (95% confidence interval: 28000-33000 ug/L); Effect: general developmental changes, craniofacial defects, abnormal gut coiling /> or =98% purity/
LC50; Species: Xenopus laevis (African clawed frog, embryo); Conditions: freshwater, renewal, pH 7.0-7.8; Concentration: 851700 ug/L for 96 hr (95% confidence interval: 818000-882000 ug/L) /> or =98% purity/
Valproic acid's production and administration as an anticonvulsant, anti-bipolar disorder and antimigraine drug may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 8.5X10-2 mm Hg at 25 °C indicates valproic acid will exist solely as a vapor in the atmosphere. Vapor-phase valproic acid will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 17 hours. Valproic acid does not contain chromophores that absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, valproic acid is expected to have high mobility based upon an estimated Koc of 47. The pKa of valproic acid is 4.6, indicating that this compound will exist almost entirely in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon a

12.2 Persistence and degradability
No data available.

12.3 Bioaccumulative potential
Log P (n-octanol/water): 2.8
Low potential for bioaccumulation (Log P < 3).

12.4 Mobility in soil
No data available.

12.5 Results of PBT and vPvB assessment
PBT/vPvB assessment not available.

12.6 Other adverse effects
No other adverse ecological effects identified.

13.1 Waste treatment methods
Waste Treatment Methods: Waste material must be disposed of in accordance with national and local regulations. Leave chemicals in original containers and do not mix with other waste. Handle uncleaned containers in the same manner as the product itself.

14.1 UN number
Not regulated as dangerous goods (research quantities typically exempt).

14.2 UN proper shipping name
Not subject to transport regulations (small quantities for research use).

14.3 Transport hazard class(es)
Not classified as dangerous goods for transport (research quantities).

14.4 Packing group
Not applicable (not regulated as dangerous goods in typical research quantities).

14.5 Environmental hazards
Marine pollutant: No (not classified as environmentally hazardous per GHS).

14.6 Special precautions for user
Transport in original packaging. Ensure containers are tightly sealed.
For bulk or commercial quantities, consult applicable transport regulations (DOT, IATA, IMDG).

14.7 Transport in bulk according to Annex II of MARPOL 73/78 and the IBC Code
Not applicable.

15.1 Safety, health and environmental regulations/legislation specific for the substance or mixture
US EPA / TSCA: Subject to EPA TSCA regulations
EU ECHA / REACH: Registered (REACH Active)

SARA 302 Components:
No chemicals in this material are subject to the reporting requirements of SARA Title III, Section 302.
SARA 313 Components:
This material does not contain any chemical components with known CAS numbers that exceed the threshold (De Minimis) reporting levels established by SARA Title III, Section 313.
SARA 311/312 Hazards:
Acute (short-term) health hazard
Chronic (long-term) health hazard

Massachusetts Right To Know Components:
This material contains components subject to the Massachusetts Right to Know Act. See Section 2 for hazard classification.
Pennsylvania Right To Know Components:
This material contains components subject to the Pennsylvania Right to Know Act. See Section 2 for hazard classification.
New Jersey Right To Know Components:
This material contains components subject to the New Jersey Right to Know Act. See Section 2 for hazard classification.

California Prop. 65 Components:
This product does not contain any chemicals known to the State of California to cause cancer, birth defects, or any other reproductive harm.

Other regulatory listings:
- The Australian Inventory of Industrial Chemicals: Chemical: Pentanoic acid, 2-propyl-
- California Safe Cosmetics Program (CSCP) Reportable Ingredient: Hazard Traits - Developmental Toxicity Authoritative List - Prop 65 Report - regardless of intended function of ingredient in the product
- EFSA Legal Basis: Commission Regulation (EC) No 1565/2000 (Repealed by Com. Implementing Reg. (EU) No 872/2012)
- FDA Requirements: The Approved Drug Products with Therapeutic Equivalence Evaluations identifies currently marketed prescription drug products, including valproic acid, approved on the basis of safety and effectiveness by FDA under sections 505 of the Federal Food, Drug, and Cosmetic Act.

15.2 Chemical safety assessment
A chemical safety assessment has not been carried out for this substance.
For research-use-only compounds, no CSA is required under REACH Annex I.

Revision Date: 2026/09/09
Further Information: The information provided is believed to be correct but is not exhaustive and should be used only as a guideline based on current knowledge. It does not represent a guarantee of the properties of the product. Selleck Chemicals Corporation and its Affiliates shall not be held liable for any damage resulting from handling or contact with the product.

Note: Technical data last updated: Sep 1, 2026.