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CAS 123-33-1

CAS 123-33-1 matches 0 EU annex records across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 123-33-1
CAS 123-33-1PubChem CID 21954

Maleic Hydrazide

IUPAC name
1,2-dihydropyridazine-3,6-dione
Molecular formula
C4H4N2O2
Molecular weight
112.09 g/mol
Exact mass
112.027277375 Da
XLogP3
-0.8
Topological polar surface area
58.2 Ų
Hydrogen-bond donors
2
Hydrogen-bond acceptors
2
Covalent units
1
Defined stereocentres
0

Also known as

3,6-Dihydroxypyridazine3,6-Pyridazinediol3,6-Pyridazinedione, 1,2-dihydro-1,2-Dihydro-3,6-pyridazinedioneMaleic acid hydrazideStuntmanVondalhydeMalzid
16 more reported names
RetardSucker-StuffAntergonAntyrostMalazideReguloxVondraxRegulox 36Maleic hydrazineSprout/offDe-sproutSprout-StopSuper-de-sproutDe-cutMaintain 3Super sucker-stuff
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match21954

Attributed physical-property, hazard, environmental and use annotations.

  • First Aid: 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.; 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.; 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) shou Source: CAMEO Chemicals
  • Note: This chemical does not meet GHS hazard criteria for 42.5% (34 of 80) of reports. Source: European Chemicals Agency (ECHA)
  • Signal: Warning Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H315 (57.5%): Causes skin irritation [Warning Skin corrosion/irritation]; H319 (57.5%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335 (56.2%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]; H341 (56.2%): Suspected of causing genetic defects [Warning Germ cell mutagenicity] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P203, P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P318, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 80 reports by companies from 7 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; Reported as not meeting GHS hazard criteria per 34 of 80 reports by companies.; There are 6 notifications provided by 46 of 80 reports by companies with hazard statement code(s).; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]; H315 (100%): Causes skin irritation [Warning Skin corrosion/irritation]; H319 (100%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335 (100%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: The GHS information provided by 1 company from 1 notification to the ECHA C&L Inventory. Source: European Chemicals Agency (ECHA)
  • Environmental Bioconcentration: An estimated BCF of 3 was calculated for maleic hydrazide(SRC), using a log Kow of -1.96 (1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: TERRESTRIAL FATE: Based on a classification scheme(1), measured Koc values of 264 for a clay soil, and 23 for a sandy loam(2), indicate that maleic hydrazide is expected to have very high to moderate mobility in soil. Maleic hydrazide exists in equilibrium with its tautomer 6-hydroxy-3(2H)-pyridazinone that has a pKa of 5.62(2), which indicates that this compound will primarily exist as an anion in moist soils and anions do not volatilize. The neutral species of maleic hydrazide is not expected to volatilize based on a Henry's Law constant of 8.1X10-9 atm-cu m/mole(2). Maleic hydrazide is not expected to volatilize from dry soils(SRC) based on a vapor pressure of 7.5X10-8 mm Hg at 25 °C(2). Biodegradation has been shown to be an important environmental fate process for maleic hydrazide in soils(2). The half-life of maleic hydrazide was reported as 2-3 days in a sandy loam used for growing potatoes, 6 days in a turfed sandy loam, and 7 days in a tobacco growing loam(2). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: AQUATIC FATE: Based on a classification scheme(1), measured Koc values of 264 for a clay soil, and 23 for a sandy loam(3), indicates that maleic hydrazide is not expected to adsorb to suspended solids and sediment(SRC). Maleic hydrazide exists in equilibrium with its tautomer 6-hydroxy-3(2H)-pyridazinone that has a pKa of 5.62(2), which indicates that this compound will primarily exist as an anion in water and anions do not volatilize. The neutral species of maleic hydrazide is not expected to volatilize based on a Henry's Law constant of 8.1X10-9 atm-cu m/mole(3). According to a classification scheme(4), an estimated BCF of 3(SRC), from a log Kow of -1.96(3) and a regression-derived equation(5), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Maleic hydrazide is stable to hydrolysis, but may undergo photochemical decomposition in sunlit surface waters(6). Maleic hydrazide (as the potassium salt) was irradiated with simulated sunlight in aqueous solutions at pH 5, 7 and 9 with calculated half-lives of 58, 58 and 34 days, respectively(6). The major product was maleate(6). Based on the rapid rate of biodegradation in soil(7), maleic hydrazide is expected Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), maleic hydrazide, which has a vapor pressure of 7.5X10-8 mm Hg at 25 °C(2), is expected to exist primarily in the particulate phase. Particulate-phase maleic hydrazide may be removed from the air by wet and dry deposition(SRC). Although maleic hydrazide absorbs light greater than 290 nm and photolyzes in aqueous solution(3), it exists primarily in the particulate phase in the atmosphere and it is unclear whether direct photolysis will be an important environmental fate process(SRC). Source: Hazardous Substances Data Bank (HSDB)

Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record

Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.

Additional source coverage and match status
SourceResultChecked
NIH PubChem PUG-ViewExact match2026-08-31

A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

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How CAS 123-33-1 is used on this site

CAS 123-33-1 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 0 EU annex records share this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 123-33-1 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.