CEPSA Acetone

Produced at the CEPSA Química integrated petrochemical complex in San Roque, Cádiz, via the cumene hydroperoxide cleavage route, the acetone co-product stream undergoes multi-stage counter-current extraction with phenol, followed by acid-catalyzed cleavage of cumene hydroperoxide and subsequent fractional distillation under reduced pressure to yield a commercial ketone conforming to ASTM D329-20 Type I specifications. Typical assay after the final polishing column, equipped with structured packing sections of 10–12 theoretical plates, exceeds 99.8% (m/m) purity when freshly distilled, with a water content held below 0.15% by mass (Karl Fischer titration per ASTM D1364), an acidity value not exceeding 0.002 mEq/g (as acetic acid, ASTM D1613), and a permanganate time consistently above 180 minutes (ASTM D1363), indicating low reactive unsaturated impurities. The product is stabilized with 15–25 ppm of 2,6-di-tert-butyl-4-methylphenol (BHT) to suppress autoxidation and peroxide formation during prolonged ambient storage in unlined carbon steel tanks under a nitrogen blanket, with a recommended tank turnover interval not exceeding 90 days to maintain test compliance. At 20 °C the liquid exhibits a density of 0.789 – 0.793 g/cm³ (ASTM D4052), a dynamic viscosity of 0.32 mPa·s, and a vapour pressure of 24.6 kPa, classifying it as a highly flammable liquid (Flam. Liq. 2; H225) under CLP Regulation (EC) No 1272/2008, with a closed-cup flash point of -17 °C (ASTM D56) and an auto-ignition temperature of 465 °C (ASTM E659). These boundaries impose ATEX Zone 1 explosion protection measures (Directive 2014/34/EU) on any processing equipment where the solvent is handled above its lower explosive limit of 2.6% (v/v) in air.

When Acetone Replaces Halogenated Solvents in Precision Cleaning of Semiconductor Substrates

Transitioning from stabilized trichloroethylene or perchloroethylene to acetone in single-wafer spin-cleaning tools or batch immersion systems introduces a flammability hazard that requires retrofitting of exhaust duct velocity monitors, hydrocarbon dew-point alarms, and electrostatic discharge control measures on all polymer-based wafer carriers. The cleaning efficacy on photoresist residues, rosin-based fluxes, and post-CMP slurries derives from acetone’s Hansen solubility parameters (δ_D ≈ 15.5 MPa^½, δ_P ≈ 10.4 MPa^½, δ_H ≈ 7.0 MPa^½), which place it within the solubility sphere of many uncrosslinked novolac resins and rosin ester binders. A documented process window exists at bath temperatures between 35 °C and 47 °C, above which excessive evaporation generates a self-cooling effect that lowers the actual solvent temperature at the part surface below the dew point, leading to localized condensation of atmospheric moisture onto the substrate when relative humidity exceeds 55%. This micro-condensation phenomenon, observed on stainless steel 316L immersion vessels with a freeboard zone of less than 150 mm, can introduce water droplets that cause galvanic corrosion on exposed aluminum bond pads unless the bath is fitted with a closed-loop condenser returning distilled acetone at a reflux ratio of 1:3. Compatibility with elastomer seals must be verified: ethylene-propylene diene monomer (EPDM) and natural rubber exhibit volumetric swell above 50% after 24 h of immersion at 25 °C, while perfluoroelastomer (FFKM) compounds such as Kalrez^® 4079 show a volume change of less than 3% under the same conditions. Metallic ion contamination of the solvent, particularly sodium and potassium above 100 ppb each as determined by inductively coupled plasma mass spectrometry (ICP-MS) per SEMI C63-0222, is known to degrade gate oxide integrity in front-end-of-line processes, making supply chain certification to SEMI Grade 4 chemical quality mandatory. Published data for this specific configuration in high-volume manufacturing is limited to parametric correlations between rinse cycle count and contact angle hysteresis on silicon dioxide surfaces.

Use of acetone as the primary let-down thinner in two-component polyurethane topcoats for Class A automotive finishes demands tight control over the water content of the solvent because residual moisture reacts competitively with aliphatic polyisocyanate hardeners (hexamethylene diisocyanate trimer) in the stoichiometric ratio of 18 g water per equivalent of isocyanate, consuming crosslinker and generating urea linkages that elevate the glass transition temperature and embrittle the film. In a typical high-solids formulation containing a maleic acid-functional acrylic polyol with a hydroxyl number of 140–160 mg KOH/g, the addition of acetone at 12–18 wt% on total binder solids reduces the spray viscosity to 22–25 s (DIN 4 mm cup at 23 °C) compatible with HVLP guns operating at 0.7 bar atomizing pressure and 1.4 mm fluid nozzle diameter. The exceptionally high evaporation rate of acetone, quantified as an evaporation rate of 5.6 relative to n-butyl acetate (ASTM D3539), must be compensated in the reducer blend by the addition of 8–12% of a slow-tail solvent such as diisobutyl ketone or 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, otherwise sagging on vertical panels occurs when the applied film loses solvent too rapidly and viscosity recovery via thixotropic agents (organoclays or fumed silica at 0.3–0.8 phr) lags behind the developing film thickness gradient. Direct substitution of acetone for toluene in a waterborne basecoat flake-control reducer is constrained by the solvent’s miscibility gap: at ambient temperatures, acetone exhibits complete miscibility with water, which can destabilize the dispersed pigment concentrate by drawing water out of the polymer emulsion droplets, causing micro-flocculation of the aluminum pigments and a consequent drop in the flip-tone index (measured on a BYK-mac i multi-angle spectrophotometer at 15° and 110° aspecular angles). The Decopaint Directive 2004/42/EC Phase II limits for ready-to-spray topcoats (max 420 g/L VOC) and the US EPA National Volatile Organic Compound Emission Standards for Automobile Refinish Coatings (40 CFR Part 59, Subpart B) categorize acetone as a VOC, despite its exemption as a hazardous air pollutant (HAP) under the Clean Air Act Section 112(b), requiring reformulation to maintain compliance through increased solids content or via capture efficiency above 92% in downdraft spray booths equipped with activated carbon adsorption wheels regenerated on a cycle time of 45 minutes at 180 °C desorption temperature.

How Does Acetone Purity Affect Bisphenol-A Yield in Polycarbonate Pre-Polymer Synthesis?

The acid-catalyzed condensation of phenol with acetone to produce bisphenol-A (4,4′-isopropylidenediphenol) is operated in a continuous fixed-bed reactor charged with a sulfonated styrene-divinylbenzene cation-exchange resin catalyst, where the stoichiometric molar ratio of phenol to acetone is maintained between 6:1 and 12:1 to suppress the formation of the undesirable 2,4′-isomer and to keep the reaction mixture fluid. Acetone feed with a purity falling below 99.7% (m/m) or containing more than 0.1% water introduces water into the catalyst bed, which hydrates the sulfonic acid groups and decreases the apparent acid strength (Hammett acidity function H₀ shifts from approximately -2.2 to values above -1.0), reducing the pseudo-first-order rate constant for p,p′-bisphenol-A formation from a design basis of 0.18 ± 0.02 h⁻¹ at 70 °C to values below 0.10 h⁻¹ at the same bed temperature. Mesityl oxide, an aldol condensation byproduct of residual acetone self-reaction catalysed by trace alkali or by prolonged residence time in the recycle loop, acts as a catalyst poison by alkylating active sites on the resin; its concentration in the acetone feed must be controlled below 50 ppm (GC-FID determination per ASTM D6139) to keep the catalyst service life above 24 months before regeneration with 2 N hydrochloric acid becomes necessary. The liquid hourly space velocity (LHSV) through the fixed bed, typically 0.8–1.2 h⁻¹ based on the total liquid flow at 60 °C inlet temperature, is constrained on the low end by the onset of bed channelling and on the high end by the adiabatic temperature rise across the bed, which for a 6:1 phenol-to-acetone molar feed reaches 18–22 °C, approaching the softening temperature of low-crosslink-density resin beads. After acid-cracked cleavage of the cumene hydroperoxide, CEPSA acetone typically reports a diacetone alcohol and mesityl oxide combined concentration below 25 ppm and an aldehyde (as propionaldehyde) content below 5 ppm, both verified by derivatization with 2,4-dinitrophenylhydrazine and HPLC-UV at 360 nm, meeting the specifications of polycarbonate producers running melt-phase transesterification with diphenyl carbonate where even trace carbonyl impurities discolour the molten polymer and raise the Yellowness Index (measured on a 3 mm plaque per ASTM D1925) above the threshold of 1.2 considered acceptable for optical media applications.

In solvent-based pressure-sensitive adhesives formulated with natural rubber and a C5 aliphatic tackifier resin, acetone functions as a process solvent for the initial mastication step as well as a coating thinner for comma-direct gravure coating heads running at web speeds of 50–120 m/min on a polyethylene terephthalate carrier of 36 μm gauge. The masticated natural rubber, typically having a Mooney viscosity ML (1+4) at 100 °C reduced from 85 to 45–55 units after kneading in acetone-swollen crumbs inside a sigma-blade mixer with a jacket temperature of 40 °C, is let down to a coating solids of 30–35% (m/m). Because acetone’s Hansen hydrogen bonding parameter (δ_H ≈ 7.0) lies distinctly outside the optimum range for tackifier resin dissolution when a substantial fraction of the resin consists of polymerized C5 piperylenes with high cyclopentadiene content, a co-solvent with a higher δ_H, such as methyl ethyl ketone at 15–22% of the solvent blend, must be introduced to eliminate visual haze from the dried adhesive film. The choice of solvent ratio directly affects the surface roughness of the dried adhesive, quantified as a root-mean-square (RMS) roughness value measured by atomic force microscopy over a 5 μm × 5 μm scan area; adhesive films cast from pure acetone exhibit an RMS roughness of 18–25 nm compared with 4–7 nm for films cast from a 70:30 (v/v) acetone/MEK blend, the higher roughness being attributed to rapid evaporation-driven skin formation that traps micro-bubbles nucleated by dissolved atmospheric oxygen. Probe tack measured per ASTM D2979-16 on a Polyken™ probe tack tester with a 5 mm diameter stainless steel probe, 1 second dwell, and 1 cm/s separation rate, decreases from an average of 650 g/cm² for the blended solvent system to 410 g/cm² for the pure acetone-cast film at the same coating weight of 25 ± 2 g/m².

Solvent Extraction of Sesquiterpene Lactones from Artemisia annua Biomass

Batch percolation extraction of artemisinin and its biosynthetic precursors from dried aerial parts of Artemisia annua, milled to pass a 2 mm sieve, is conducted in a series of three static extractors, each of 5,000 L capacity, where acetone of 99.5% minimum purity is circulated at a solvent-to-biomass ratio of 8:1 (L/kg) and held at 45 °C for 4 h under a slight nitrogen overpressure of 0.5 bar to minimize peroxide-induced degradation of the endoperoxide bridge critical for antimalarial activity. The extract liquor is concentrated in a wiped-film evaporator with a jacket temperature of 65 °C and a rotor speed of 150 rpm, reclaiming approximately 92% of the acetone for reuse, while the oleoresin is subjected to an anti-solvent crystallization with hexane at 5 °C. Residual acetone in the final crystalline artemisinin complies with the International Conference on Harmonisation (ICH) Q3C(R8) guideline for a Class 3 solvent, where the permitted daily exposure is 50 mg/day, translating to a concentration limit of 5000 ppm in the drug substance, verified by headspace gas chromatography with flame-ionization detection using a DB-624 column (30 m × 0.53 mm, 3 μm film) and an equilibration temperature of 80 °C for 30 minutes. An operational boundary arises when the recycled acetone accumulates saponins and chlorophyll derivatives that form emulsions during subsequent extraction runs; these secondary metabolites increase the interfacial tension between the solvent and the aqueous cellular fluid, and when their concentration exceeds 1.2 g/L (measured as total dry residue at 105 °C), the raffinate phase separation time in the decanter extends beyond 30 minutes, necessitating a bleed stream of 15% of the recycled acetone to be diverted to a distillation column with 15 stages operating at a reflux ratio of 2.5 for purification.

The immersion of polycarbonate components in acetone for surface cleaning or paint stripping purposes, even at ambient temperature, carries a well-documented risk of environmental stress cracking (ESC) arising from the solvent’s solubility parameter proximity to that of the bisphenol‑A polycarbonate matrix (δ ≈ 20.3 MPa^½). Under a constant tensile strain of 0.3%—corresponding to the residual molding stress in a part ejected from an injection tool with a hot runner system at a mold temperature of 90 °C—crazing initiates within 40 seconds of acetone exposure, as documented by optical profilometry of the surface, with crack propagation rates following an empirical correlation of v = A·K_Iⁿ where n approaches 8–10 for this polymer‑solvent pair. This fast failure mode precludes any production‑line use of acetone as a wipe solvent for polycarbonate optical lenses, glazing sheets, or medical device housings without prior application of a crosslinked siloxane hard‑coat that raises the critical strain for crazing to above 1.5%. Low‑density polyethylene and polypropylene, by contrast, exhibit gravimetric weight gains of less than 0.5% and maintained tensile strength at yield (ASTM D638‑14, Type IV specimen, 50 mm/min) within 2% of original values after 72 h of immersion, making acetone a viable cleaning rinse for polyolefin containers before adhesive labeling, provided the container surface temperature remains below 35 °C to avoid excessive swell and distortion of thin‑walled parts.

For the synthesis of methyl methacrylate (MMA) via the acetone cyanohydrin (ACH) route, the starting acetone is reacted with hydrogen cyanide in a continuous stirred‑tank reactor at a pH controlled between 7.2 and 7.8 by the addition of 30% aqueous sodium hydroxide, with the exothermic cyanohydrin formation kept at a temperature not exceeding 25 °C by an external ammonia‑based refrigeration loop circulating at -10 °C through a dimpled jacket. The reactor effluent, containing acetone cyanohydrin together with unreacted acetone and traces of hydrogen cyanide, is stabilized with sulfuric acid to a pH of 2.0 and forwarded to a amidification reactor operating at 105–115 °C, where conversion to methacrylamide sulfate is carried out in 98% sulfuric acid. Acetone introduced into this process must contain less than 0.05% water to avoid hydrolysis of HCN to formamide and subsequent generation of ammonium bisulfate that precipitates as a scale in the tube side of the shell‑and‑tube amidification heat exchanger, reducing the overall heat‑transfer coefficient from a clean value of 450 W/m²·K to below 200 W/m²·K within six weeks of continuous operation as determined by process-side pressure-drop trend analysis. The specification for methanol content in the acetone feed is set below 100 ppm because methanol reacts with hydrogen cyanide under the alkaline cyanohydrin reactor conditions to form methoxyacetonitrile, an azeotroping impurity that, if carried forward, contaminates the final MMA product and shifts its boiling point by 0.8 °C per 1000 ppm impurity, rendering it off‑specification for polymerization‑grade monomer as per ASTM D5963‑22.

Managing Exothermic Peaks in Acetone-Diluted Epoxy Infusion for Wind Turbine Blades

Vacuum‑assisted resin transfer molding (VARTM) of glass‑fibre‑reinforced epoxy composites for rotor blades of 45–80 m length routinely employs a reactive diluent blend containing acetone at 8–14% by weight of the epoxy component to reduce the initial mixed viscosity to 200–350 mPa·s at 25 °C, measured on a Brookfield DV3T rheometer with an SC4‑27 spindle at 50 rpm, ensuring complete wetting of the triaxial non‑crimp fabric stack within a mould filling time not exceeding 90 minutes before the gel point is reached. The acetone must be stripped from the laminate under a vacuum of less than 20 mbar absolute for a dwell period of 4–6 hours at 40 °C before the exothermic cure is initiated, because acetone that remains solvated in the resin phase depresses the glass transition temperature of the fully cured network by 8–12 °C for each weight percent of residual solvent, measured by dynamic mechanical analysis (DMA) at a frequency of 1 Hz as the onset of the storage modulus drop. Process engineering data from industrial VARTM lines indicate that the latent heat of evaporation of acetone (501 kJ/kg at 56 °C) combined with the evaporative cooling effect inside the partially evacuated mould can impose a temperature gradient of 12 °C between the surface ply and the core if the mould tool is not equipped with an active fluid heating circuit maintaining the bottom skin at 35–40 °C; this gradient leads to a corresponding gradient in resin cure advancement and results in spring‑in discrepancies of 1.2–2.4 mm over the chord length on demoulding, deviating from the aerodynamic tolerance of ±0.8 mm required for Class A surface finish. Volatile organic compound emissions during the vacuum stripping stage must be captured by a liquid‑ring vacuum pump using water as the seal fluid and routed to a packed‑bed scrubber with an air‑to‑water volumetric ratio of 120:1 at a superficial gas velocity of 1.8 m/s through 2.5 m of 25 mm polypropylene Pall rings, achieving a removal efficiency of 97% for acetone before atmospheric discharge, as validated by a flame‑ionization detector exhaust monitor logging at 30‑second intervals.

In the formulation of non‑acetone nail polish removers—an ironic niche where acetone is nonetheless used as a co‑solvent in small proportions to adjust the dielectric constant of the mixture—blends of ethyl acetate, propylene carbonate, and acetone in a volumetric ratio of 50:35:15 are reported to lower the Hildebrand solubility parameter of the mixture to 19.8 MPa^½, sufficient to dissolve cellulose nitrate lacquers without the extreme degreasing and delipidation of the keratin nail plate that pure acetone causes within 5–7 seconds of contact, as quantified by a reduction in nail plate surface free energy (determined by sessile‑drop contact angle goniometry with water, diiodomethane, and ethylene glycol) from 42 mJ/m² to 26 mJ/m². Addition of acetone beyond 20% (v/v) triggers an abrupt rheological shift in the formulation when d‑panthenol or glycerin at 1–3% is employed as a plasticizing humectant, because the low‑molecular‑weight ketone disrupts the hydrogen‑bonded network of the polyol, causing phase separation visible as a translucent precipitate after 48 hours of shelf storage at 40 °C accelerated stability testing per ISO 22716 Section 8 guidelines.

Acetone’s function as a mobile phase modifier in normal‑phase flash chromatography for the purification of synthetic intermediates exploits its ability to adjust the solvent strength parameter (ε°) on silica gel; a binary mixture of hexane and acetone in a volumetric ratio of 85:15 to 60:40 spans an ε° range of 0.18 to 0.38, sufficient to resolve closely eluting diastereomers with separation factors (α) between 1.08 and 1.25 as measured on a 20 μm silica‑60 stationary phase packed in a 400 g column at a flow rate of 60 mL/min and a backpressure of 2.8 bar. The presence of peroxide impurities in recycled acetone that has been stored in the absence of inhibitor for longer than 30 days at ambient laboratory conditions is a critical hazard during the evaporation of post‑chromatography fractions because accumulation of peroxides in the still bottoms beyond 30 ppm (as hydrogen peroxide, determined by iodometric titration per ASTM E298‑17) can lead to spontaneous, thermo‑sensitive decomposition when the heating bath temperature surpasses 85 °C, causing a pressure surge in rotary evaporator glassware rated only to 1 bar of differential pressure. A peroxide-testing protocol using Merckoquant^® test strips with a detection threshold of 0.5 ppm before every distillation run, coupled with the addition of 5 mg/L of hydroquinone monomethyl ether as a short‑term stabilizer when the overhead distillate is to be stored beyond 48 hours, is standard practice in kilo‑lab synthesis suites compliant with the Chemical Safety Board recommendation 2005‑03‑I‑OR.