Overview & Basic Properties
Butyraldehyde (commonly called butyraldehyde) has the chemical
formula C4H8O and CAS number 123-72-8. It is a colorless, transparent liquid with a strong, pungent aldehydic odor. The aldehyde functional group (-CHO) gives it high reactivity in many organic reactions, making it an essential intermediate in industrial chemistry.
Physical properties: Melting point ≈ −96 °C; Boiling point ≈ 75.7 °C; Density ≈ 0.80 g/cm³ (20 °C).
Solubility: Slightly soluble in water; miscible with ethanol, ether and most common organic solvents.
Chemical behavior: Undergoes oxidation, reduction, condensation and addition reactions typical of aldehydes.
Major Applications of
1. Fine Chemicals & Pharmaceuticals
Butyraldehyde is widely used as an intermediate in pharmaceutical syntheses. It participates in the production of:
Vitamin B6 derivatives and related intermediates.
Anti-tuberculosis agent precursors (e.g., isonicotinyl hydrazide derivatives).
Nucleoside and antiviral drug intermediates where the aldehyde unit is required for further functionalization.
2. Agrochemicals
Used to prepare intermediates for sulfonylurea herbicides and advanced insecticidal molecules, where precision substitution on the carbon chain is important for activity and selectivity.
3. Polymers, Resins & Plastics
Butyraldehyde acts as a precursor in manufacturing:
Polyvinyl butyral (PVB) and derivatives — improving film properties and used in laminated glass.
Plasticizer intermediates for PVC and other polymer systems, enhancing flexibility.
4. Rubber & Elastomers
Employed in the synthesis of certain vulcanization accelerators and additives that improve elasticity and aging resistance for tires and sealing components.
5. Fragrances & Flavors
In highly diluted form, it contributes fruity notes (e.g., banana or caramel-like) used in flavor and fragrance formulations. Strict dilution and regulatory checks apply for food-use applications.
6. Environmental & Other Industrial Uses
Used as a building block for VOC control agents and specialty coatings, as well as in dye and leather auxiliaries.
Production Methods
1. Hydroformylation (Oxo Process) of Propene — Main Industrial Route
Hydroformylation (also called the oxo process) of propene with CO and H₂ is the dominant industrial method. Key points:
Feedstock: Propene, carbon monoxide and hydrogen.
Catalysts: Cobalt-based systems (traditional) or modified rhodium-phosphine catalysts (modern, higher selectivity).
Typical conditions: Cobalt: ~150–160 °C at ~27–28 MPa; Rhodium systems operate at lower pressures and temperatures (e.g., 100–120 °C, 0.7–2 MPa).
Performance: Overall yields commonly 80–85%; optimized continuous systems can exceed 90% selectivity toward Butyraldehyde.
2. Dehydrogenation of n-Butanol
n-Butanol can be dehydrogenated to produce Butyraldehyde using metal catalysts (Ni, Cu/Cr oxides) under elevated temperatures (≈200–250 °C). This route is simpler but raw material costs and catalyst life are considerations.
3. Emerging & Green Routes
Research focuses on bio-based feedstocks (e.g., catalytic transformation of furfural or biomass-derived intermediates) and continuous microreactor processes for better control, higher selectivity and reduced waste.
Safety & Environmental Controls
Hazards
Butyraldehyde is flammable and an irritant to eyes, skin and respiratory system. It may cause headaches, dizziness or more severe effects at high exposures.
Safe Handling & PPE
Perform operations in well-ventilated areas or approved fume hoods.
Use anti-static, explosion-proof equipment and eliminate ignition sources.
Personal protective equipment: chemical-resistant gloves (nitrile), goggles/face shield, flame-resistant lab wear and access to safety shower/eye wash.
Storage & Transport
Store in sealed containers in cool, dry, and ventilated areas away from oxidizers and acids. Transport as flammable liquid per relevant ADR/IMDG/IATA regulations; avoid mixing with food cargo.
Spill & Emergency Response
Contain spills using inert absorbents (vermiculite, sand). Prevent entry to drains. For large spills, evacuate and call emergency response teams. Contaminated absorbent must be disposed of per hazardous waste regulation.
Waste & Emission Controls
VOC emissions: treat with alkaline scrubbers, thermal oxidizers or catalytic oxidation systems to meet local standards.
Wastewater: apply biological treatment or advanced oxidation (AOP) to remove residual aldehydes before discharge.
Future Trends & Innovations
Industry and research are driving butyraldehyde production and application toward greener and higher-value directions:
Green Catalysis: Development of recyclable, water-tolerant rhodium-phosphine catalysts and non-precious metal alternatives to reduce metal residue and catalyst cost.
Continuous & Microreactor Processing: Microchannel reactors and continuous flow systems allow superior heat/mass transfer, tighter selectivity control and improved safety.
Bio-based Feedstocks: Catalytic conversion from biomass derivatives (e.g., furfural) to lower fossil carbon footprint.
High-Value Derivatives: Focus on specialty chemicals and functional materials derived from butyraldehyde with greater margins and stricter environmental compliance.
Conclusion
Butyraldehyde (C4H8O) is a versatile and broadly used aldehyde intermediate critical to pharmaceuticals, agrochemicals, plastics, rubber and fragrance industries. Modern production emphasizes selectivity, safety and environmental compliance, while innovation trends favor green feedstocks and continuous processing to enhance sustainability and cost efficiency.