GLYOXAL 40%

Glyoxal (IUPAC: oxaldehyde; formula OCHCHO, MW 58.04 g·mol⁻¹) was first prepared and described in the 19th century. 
Historically, it was prepared by oxidizing ethanol or acetaldehyde and later produced on industrial scale by controlled oxidation of ethylene glycol or acetaldehyde derivatives. 
Modern demand is driven by its role as a crosslinker and a building block for specialty resins and chemical intermediates. 
Commercial glyoxal is typically supplied as a 40% aqueous solution for reasons of stability, handling, and the compound’s tendency to hydrate and oligomerize in water.

CAS number: 107-22-2.
Synonyms / other names: glyoxal, ethanedial, oxalaldehyde, 1,2-ethanedione, glyoxylaldehyde, biformal, biformyl, diformal, diformyl, oxaldehyde; also sold as glyoxal solution (40%).
Chemical identity and molecular structure

Molecular formula: C₂H₂O₂ (conventionally written OCHCHO).

Molecular weight: 58.04 g·mol⁻¹. 
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Glyoxal is the simplest dialdehyde (two aldehyde groups on adjacent carbon atoms). 
In the gas or solid phase the monomeric dialdehyde structure is relevant, but in aqueous solution glyoxal readily forms hydrates (gem-diols), hemiacetals, and higher oligomers (dimers, trimers) via hydration and acetalization pathways. 
The solution species distribution depends on concentration, pH, temperature and solvent composition; at industrial concentrations (≈40% w/w) a complex equilibrium mixture of monomer, hydrates and oligomers exists and determines its reactive behavior. 

Physical and physicochemical properties (commercial 40% solution & monomer)
Below are representative values commonly reported for commercial glyoxal 40% solutions and for the glyoxal monomer.
Glyoxal (monomer)
Appearance: colorless to light yellow liquid or crystals (solid at low temperature).
Melting point (monomer/hydrate/solid): ~15 °C (monomer reported values vary due to hydrates).
Boiling point (pure monomer): ~50.5 °C (note: monomer is rarely isolated).
Density (approx. monomer): ~1.26 g·cm⁻³ (20 °C reported). 
Glyoxal 40% w/w aqueous solution (typical commercial product)
Appearance: colorless to yellow liquid (slight yellow sometimes from impurities/oligomers).
Density (approx): ~1.20–1.26 g·mL⁻¹ depending on formulation.
Refractive index (reported): ~1.409 (40% w/w).
Melting / Freezing behavior: depressed relative to monomer due to water and hydrates; commercial solutions remain liquid at typical ambient temperatures.
pH: typically slightly acidic to neutral depending on stabilizers; many commercial grades are slightly acidic. 

Solution chemistry remarks: glyoxal’s apparent physical properties in solution are dominated by hydrated forms and oligomers; therefore, parameters such as “effective free dialdehyde concentration” are operational and depend on analytical method used. 

Manufacture and industrial production routes
Industrial glyoxal is produced by controlled oxidation of small oxygenated hydrocarbons. Two principal historical/industrial methods:
Gas-phase oxidation of ethylene glycol (Laporte-type processes) using catalysts (silver, copper), yielding glyoxal vapor subsequently condensed into aqueous solution. 
This route is widely used industrially.
Liquid-phase oxidation of acetaldehyde (e.g., with nitric acid or other oxidants) — used in other plants.

Large producers (e.g., BASF and others) operate integrated plants producing and stabilizing glyoxal as 40% aqueous solution for transport and sale. 
Commercial manufacturing emphasizes control of by-products, minimization of over-oxidation (to glyoxylic/oxalic acids), and control of oligomer distribution. 

Solution speciation and chemistry in water
Glyoxal in water does not exist only as the free dialdehyde. Primary aqueous species include:
Monomeric glyoxal (OCHCHO) — present to some extent at low concentrations/low water activity.
Geminal diols (hydrates): addition of water to each aldehyde yields diol forms (—CH(OH)₂), stabilized in water.
Hemiacetals / acetals and oligomers: hydrate-derived hydroxyls and remaining aldehyde groups react intermolecularly forming cyclic and linear oligomers (dimers, trimers). 
A commercially sold trimer dihydrate ([(CHO)₂]_3(H₂O)₂) is known.

Reactivity implications: the actual concentration of the reactive dialdehyde depends on the equilibrium distribution; nevertheless, many industrial processes simply exploit the reactivity of the ensemble (hydrate + reversible aldehyde) as a functional crosslinking “glyoxal equivalent.” 

Key reactions and mechanistic behavior
Glyoxal is electrophilic at both carbonyl carbons and undergoes multiple classes of reactions:
Schiff base formation (imine formation) with primary amines: glyoxal reacts readily with amines to form imines and crosslinked networks; these reactions underpin its use as a crosslinker for proteins, cellulose, and polyamines.

Crosslinking with hydroxyl-containing polymers (cellulosic fibers): formation of acetal/hemiacetal linkages or other covalent bonding under acidic or catalytic conditions leads to improved wrinkle resistance in textiles and paper sizing.
Reaction with urea/urea derivatives to form glycoluril-type structures: used to synthesize glycoluril monomers for amino-resin systems (e.g., for powder coatings).
Oxidation/transformation: glyoxal may be further oxidized to glyoxylic and oxalic acids under strongly oxidative conditions.
Polycondensation/oligomerization: self-condensation leads to oligomeric products useful or problematic depending on application/storage conditions. 

Kinetic behavior depends strongly on pH, temperature, concentration, and presence of catalysts (acids, Lewis acids). 
Under mildly acidic conditions, acetalization/crosslinking is favored for cellulose/textiles; at higher pH, other reaction pathways and decomposition may become competitive.

Analytical methods and quality control
Common analytical objectives: total glyoxal content (often as “free dialdehyde” or equivalent), water content, impurities (glyoxylic acid, formaldehyde, residual acetaldehyde), oligomer distribution, density, refractive index, pH.
Methods:
Titrimetric / derivatization approaches: reaction with 2,4-dinitrophenylhydrazine (DNPH) derivatives or other aldehyde-specific reagents followed by HPLC or UV–visible determination is used for quantifying dialdehydes.

HPLC (reverse-phase) with derivatization: derivatize aldehydes to stable hydrazones or imines, separate by HPLC and quantify by UV or MS.
NMR spectroscopy: to probe species distribution, degree of hydration and oligomerization in solution.
GC (after derivatization): volatile derivatives of glyoxal can be analyzed by GC-MS.
FTIR / UV-Vis: qualitative monitoring of functional groups and some derivatives.
Physicochemical QC: density, refractive index, and Brix are used as quick QC checks for batch acceptance.
SDS/MSDS and heavy-metal testing: suppliers provide certificates of analysis with limits for impurities. 
Analytical choice depends on whether measuring “total glyoxal equivalents” (functional reactivity) or free monomer concentration; for application-driven QC, functional reactivity assays (e.g., crosslinking efficacy) are often used alongside chemical quantification.

Industrial and technical applications
Glyoxal 40% is a versatile industrial chemical with broad application classes:
Textiles: glyoxal acts as a crosslinker to produce wrinkle-resistant (easy-care) finishes on cotton and blended fabrics. 
It reacts with cellulose hydroxyls to form crosslinks that decrease dimensional change on washing. 
Paper & board: used for wet-strength and dry-strength enhancement, internal sizing, and crosslinking in coatings.
Leather tanning: as a crosslinker and tanning aid improving texture and durability. 
Coatings & resins: precursor to glycoluril-based amino crosslinkers used in powder coatings, can & coil coatings; glyoxal-derived crosslinkers often emit less formaldehyde relative to some older amino-resin systems. 
Polymer and chemical intermediates: glyoxal condenses with urea/urethane/amine systems to produce crosslinking resins and specialty chemicals.
Water treatment and biocide applications: glyoxal exhibits biocidal properties and can be used in certain water-treatment or preservative formulations (use regulated and formulation-dependent). 
Laboratory use and histology: glyoxal solutions can be used as fixatives for tissue preparations (though formalin is more common); alternative low-formaldehyde fixatives are an area of interest. 
Adhesives and paper coatings: as crosslinker or reactive additive to improve film properties, wet strength or solvent resistance.
Because glyoxal forms less formaldehyde on curing in some systems (compared to formaldehyde-based crosslinkers), it has been promoted as a lower-emitting alternative in some coating/resin applications — although glyoxal has its own toxicity and regulatory considerations.

SAFETY INFORMATION ABOUT GLYOXAL 40%

First aid measures:
Description of first aid measures:
General advice:
Consult a physician. 
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
 
If inhaled:
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately. 
Wash off with soap and plenty of water.
Consult a physician.
 
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
 
If swallowed:
Do NOT induce vomiting. 
Never give anything by mouth to an unconscious person. 
Rinse mouth with water. 
Consult a physician.
 
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
 
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment. 
 
Avoid breathing vapours, mist or gas. 
Evacuate personnel to safe areas.
 
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste. 
Keep in suitable, closed containers for disposal.
 
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
 
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place. 
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
 
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
 
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles. 
Faceshield (8-inch minimum). 
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
 
Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
 
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
 
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. 
 
If the respirator is the sole means of protection, use a full-face supplied air respirator. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so. 
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions. 
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
 
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company. 
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product