| HS Code | 121144 |
| Product Name | Benzyl Cyanide |
| Synonyms | Phenylacetonitrile; 2-Phenylacetonitrile; alpha-Tolunitrile; Benzyl nitrile |
| Cas Registry Number | 140-29-4 |
| Ec Number | 205-410-5 |
| Molecular Formula | C8H7N |
| Molecular Weight | 117.15 g/mol |
| Iupac Name | Phenylacetonitrile |
| Appearance | Colorless to light yellow oily liquid |
| Odor | Aromatic |
| Density | 1.015 g/cm3 at 25 °C |
| Melting Point | -24 °C |
| Boiling Point | 233-234 °C |
| Flash Point | 101 °C (closed cup) |
| Refractive Index | 1.5230 at 20 °C |
| Solubility In Water | Slightly soluble |
| Solubility In Organic Solvents | Miscible with ethanol, ether, chloroform, benzene |
| Vapor Pressure | 0.1 mmHg at 20 °C |
| Logp | 1.56 |
| Autoignition Temperature | 555 °C |
| Un Number | 2470 |
| Hazard Class | 6.1 |
| Packing Group | III |
| Storage Conditions | Store in a cool, dry, well-ventilated area away from ignition sources |
| Decomposition Products | Hydrogen cyanide, nitrogen oxides, carbon monoxide, carbon dioxide |
As an accredited Benzyl Cyanide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Benzyl Cyanide is supplied in 25 kg UN-approved steel drums, securely sealed and labeled with appropriate hazard warnings. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Benzyl Cyanide in UN-approved drums, secured and labeled Class 6.1 toxic, including dangerous goods documentation. |
| Shipping | Benzyl cyanide is shipped as a hazardous material: UN 2470, Class 6.1 (Toxic), Packing Group III. Use approved, tightly closed containers with Toxic labels and proper shipping papers. Follow DOT/IATA/IMDG regulations, segregate from incompatible materials, and protect from heat, moisture, and physical damage. |
| Storage | Store benzyl cyanide in a tightly closed, properly labeled container in a cool, dry, well-ventilated, fire-safe area. Keep away from heat, ignition sources, strong oxidizers, acids, and bases. Use secondary containment, grounding/bonding, and locked storage. Protect from moisture and light. Store in original packaging, avoid static discharge, and follow local regulations and SDS requirements. |
| Shelf Life | Benzyl cyanide shelf life is typically 2–3 years when stored sealed, cool, dry, and protected from light, moisture, and oxidizers. |
Benzyl cyanide is first hydrolyzed to phenylacetic acid in glass-lined or fluoropolymer-lined reactors charged with 60–70% sulfuric acid at 90–105 °C; the exothermic hydrolysis requires staged water addition to maintain acid concentration within ±2 °C and prevent thermal decomposition of the intermediate phenylacetamide. The off-gas ammonia is scrubbed into ammonium sulfate. The recovered phenylacetic acid, assay not less than 98.5% on anhydrous basis and melting point 76–77 °C, is converted to sodium phenylacetate feed solution at 20–25% w/v for downstream β-lactam antibiotic fermentation. In 120,000–220,000 L stirred-tank fermenters, dissolved oxygen is maintained at 30–40% of air saturation, pH at 6.4–6.6, and residual phenylacetic acid below 1.0 g/L; exceeding this residual threshold suppresses penicillin G synthase and shifts carbon toward mycelial growth instead of antibiotic biosynthesis. Residual phenylacetic acid is measured by HPLC with a C18 column and UV detection at 254 nm, validated per ICH Q2(R1). The sodium phenylacetate feed is initiated after 48 h of batch growth and is regulated by continuous HPLC monitoring of residual phenylacetic acid rather than a fixed volumetric rate. Penicillin G potassium or sodium is isolated by solvent extraction, carbon treatment, and crystallization according to ICH Q7 Section 12.6. Compliance includes 21 CFR 210 and 211, EU GMP Part II, and the USP penicillin G potassium or Ph. Eur. penicillin G sodium monograph. Finished products are penicillin G potassium and sodium sterile injectable powders, oral suspensions, and dry syrup formulations.
The condensation of benzyl cyanide with 2-chloropyridine to α-phenyl-2-pyridineacetonitrile is carried out in a jacketed glass-lined reactor fitted with a reflux condenser, nitrogen purge, and reactor pre-drying to ≤100 ppm water, because sodium amide charged at 2.0–2.5 mol per mol benzyl cyanide hydrolyzes exothermically to sodium hydroxide and ammonia, consuming the base and releasing ammonia that can convert 2-chloropyridine to 2-aminopyridine. The molar ratio of 2-chloropyridine to benzyl cyanide is held at 1.05:1–1.20:1; lower ratios leave unreacted benzyl cyanide in the crude reaction mass, while higher ratios raise dimeric impurities in the subsequent hydrogenation. Reaction temperature is stepped from 60 °C to 95 °C over 12 h, after which quench is performed with 5–10% aqueous ammonium chloride. Reaction endpoint is confirmed by GC area normalization with benzyl cyanide below 0.5%. The resulting nitrile is hydrolyzed with 60–65% sulfuric acid at 110–120 °C to give phenyl(2-pyridyl)acetic acid; this acid is then hydrogenated in glacial acetic acid over platinum oxide at 0.3–0.5 MPa hydrogen to reduce the pyridine ring to piperidine. Esterification with methanolic hydrogen chloride produces methylphenidate hydrochloride, which is recrystallized to 99.5% assay. Compliance includes the USP methylphenidate hydrochloride monograph, ICH Q3C residual solvent limits, 21 CFR 1308.12 Schedule II handling and quota controls, and ICH Q7 active pharmaceutical ingredient manufacturing requirements. Finished products include immediate-release 5 mg, 10 mg, and 20 mg tablets, extended-release capsules, and transdermal patches.
In the barbiturate synthesis chain, benzyl cyanide is first activated as ethyl phenylacetate; the ester is condensed with diethyl carbonate in the presence of sodium ethoxide at 60–70 °C, with diethyl carbonate charged at 1.2–1.5 mol per mol phenylacetate to force diethyl phenylmalonate formation. The condensed ester is then alkylated with ethyl bromide at 0–5 °C in ethanol, and the resulting ethylphenylmalonate is cyclized with urea in a 60–70 °C sodium ethoxide/ethanol system to close the barbiturate ring. The critical process limit is water content: if free water rises above 0.5% in the ethanolic condensation, sodium ethoxide is hydrolyzed and the malonate condensation stalls; therefore the reactor is purged with dry nitrogen and ethanol is dried over 3 Å molecular sieves before charging. The malonate condensation is monitored by loss of diethyl carbonate and by GC, and the alkylation endpoint is checked by thin-layer chromatography. The crude phenobarbital is recrystallized from ethanol/water to meet the USP phenobarbital monograph and the current Ph. Eur. phenobarbital monograph; as a Schedule IV controlled substance under 21 CFR 1308.13, quota allocation, batch reconciliation, and controlled storage are mandatory. Compliance is additionally aligned to ICH Q7 Section 7.3 for material recovery and reuse. Finished products include 15 mg, 30 mg, and 60 mg tablets and injectable phenobarbital sodium.
Following the catalytic reduction of benzyl cyanide, selectivity to phenylacetaldehyde is maintained in a fixed-bed hydrogenation reactor using a selectively poisoned palladium catalyst under acidic aqueous conditions; hydrogen pressure is held at 0.3–0.8 MPa and temperature at 50–80 °C to limit over-reduction to phenethyl alcohol when the aldehyde is the target. The reactor exit stream is quenched into dilute acid to hydrolyze the imine intermediate, then distilled under reduced pressure to isolate phenylacetaldehyde at ≥97.0% assay. In hyacinth and rose fragrance concentrates, phenylacetaldehyde is dosed at 0.05–0.5 wt% of the perfume oil and phenethyl alcohol at 1.0–5.0 wt%; the aldehyde is restricted by skin sensitization and is stabilized with triethyl citrate or dipropylene glycol before incorporation. Compliance for fragrance intermediates follows EU Regulation 1223/2009 for cosmetic products, EU Regulation 1334/2008 for flavoring substances where the corresponding esters enter food, and the IFRA Standard for phenylacetaldehyde. Terminal product types include fine fragrance alcohol solutions, hydroalcoholic personal care formats, and household liquid cleaners at lower doses.
Ethyl phenylacetate and methyl phenylacetate are produced by Fischer esterification of benzyl cyanide-derived phenylacetic acid with ethanol or methanol in glass-lined or stainless steel reactors; alcohol is charged at 3–6 mol per mol phenylacetic acid, sulfuric acid or p-toluenesulfonic acid at 0.5–1.0 wt%, and water is removed azeotropically through a column at 78–82 °C to shift conversion above 98%. The esters are washed with dilute sodium bicarbonate and distilled under vacuum through a packed column to achieve ≥98.0% assay. The critical control is residual benzyl cyanide in the final ester: after distillation, residual nitrile must be below 0.1 mg/kg due to its toxicity and odor threshold, and this is verified by GC-MS with a limit of quantitation of 0.05 mg/kg, following ICH Q3C-style validation. Compliance for ester applications includes EU Regulation 1334/2008, 21 CFR 172.515, and the FCC monograph assays for ethyl phenylacetate and methyl phenylacetate. Terminal products include fruit, honey, cocoa, and rose flavor compounds supplied as certified flavours to food and beverage manufacturers.
| Parameter | Ethyl phenylacetate | Methyl phenylacetate |
|---|---|---|
| Alcohol-to-phenylacetic acid molar ratio | 3:1–6:1 | 3:1–6:1 |
| Catalyst loading | 0.5–1.0 wt% | 0.5–1.0 wt% |
| Distillation assay | ≥98.0% | ≥98.0% |
| Residual benzyl cyanide | ≤0.1 mg/kg | ≤0.1 mg/kg |
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Benzyl cyanide, systematically named phenylacetonitrile and assigned CAS 140-29-4, is a colourless to pale yellow liquid with the molecular formula C8H7N and a molar mass of 117.15 g/mol. The substance is also designated α-tolunitrile or benzyl nitrile. At atmospheric pressure, it melts at -23.8 °C and boils at 233.5 °C. Its density is 1.015 g/cm³ at 20 °C, and the refractive index at 20 °C is 1.5230. The closed-cup flash point is 101 °C, placing the liquid in the combustible rather than highly flammable classification under many transport and storage schemes. Water solubility is low, and the compound is normally handled as an organic phase in process operations.
Industrial production is dominated by the nucleophilic substitution of benzyl chloride with sodium cyanide in an aqueous or aqueous–organic reaction medium. Published process descriptions commonly specify phase-transfer catalysis and subsequent vacuum distillation to separate benzyl cyanide from residual benzyl chloride and higher-boiling by-products. On production-scale equipment, the reaction is run in glass-lined or stainless-steel stirred vessels, and the distillation train usually includes a packed or structured column under reduced pressure. The product is dried and stored under nitrogen to maintain the moisture specification required for downstream catalytic hydrogenation.
Commercial documentation does not typically assign model numbers to benzyl cyanide. Instead, the product is differentiated by grade designations such as technical grade and pharmaceutical-intermediate grade, which are defined by the specification profile rather than by model nomenclature. The specifications in the following section therefore serve as the product definition.
Regulatory status is not uniform across jurisdictions. Because benzyl cyanide is a phenylacetic acid precursor, it may be listed under national drug precursor schedules. Import, export, and end-use documentation should be verified against the relevant national competent authority before shipment. Published data for this specific configuration is limited, so classification must be confirmed jurisdiction by jurisdiction.
Pharmaceutical and fine-chemical purchasers typically specify benzyl cyanide by a small set of purity and impurity limits rather than by model designations. The following profile represents a standard pharma-intermediate grade; technical-grade material may allow higher colour and greater residual benzyl chloride.
| Parameter | Limit | Test Method |
|---|---|---|
| Appearance | Clear, colourless to pale yellow liquid | Visual inspection |
| Assay | ≥ 99.0% | GC-FID with internal standard |
| Moisture | ≤ 0.10% | ASTM E203 |
| Density at 20 °C | 1.014–1.016 g/cm³ | ASTM D4052 |
| Refractive index nD20 | 1.522–1.524 | ASTM D1218 |
| Boiling range | 232–235 °C, IBP to DP not exceeding 2.0 °C | ASTM D1078 |
| Benzyl chloride | ≤ 0.10% | GC-FID |
| APHA colour | ≤ 20 | ASTM D1209 |
The benzyl chloride residual is critical for hydrogenation steps because residual organic chloride can poison supported metal catalysts and contribute to stainless-steel corrosion after hydrolysis. The moisture limit is also not arbitrary. Water present during alkali-metal amide alkylation consumes the base and changes the apparent stoichiometry, while water in catalytic hydrogenation can increase ammonia recovery load. Bulk shipments are therefore often loaded under a dry nitrogen pad and sampled with closed-loop systems to prevent moisture ingress.
In phase-transfer-mediated alkylation, benzyl cyanide is added to a two-phase system consisting of toluene and 50 wt% aqueous sodium hydroxide. The methylene bridge is deprotonated at the interface, and the resulting phenylacetonitrile anion is alkylated with an alkyl halide or dialkyl sulfate. With tetrabutylammonium bromide as catalyst, the reaction is maintained at 30–50 °C to limit exothermic excursion and reduce formation of dialkylated by-product. The exotherm is controlled by dosing rate and internal coil or jacket cooling. For monoalkylation with methyl chloride, the molar feed ratio of benzyl cyanide to methyl chloride is typically held between 1:1.05 and 1:1.20. The selectivity to monoalkylated product depends on the interfacial concentration of the phenylacetonitrile anion and on the rate of alkylation relative to further deprotonation of the product. If the aqueous sodium hydroxide concentration is too high, the product can be deprotonated a second time, leading to geminal disubstitution, which is a common batch failure mode observed in agitated vessels with poor phase mixing.
The reaction mass is quenched with water, the organic layer is washed to remove sodium chloride and excess alkali, and the solvent is recovered by distillation. The crude product is fractionated under vacuum to separate residual benzyl cyanide from the monoalkylated product. The relevant infrared marker for the nitrile group is the C≡N stretch at approximately 2245 cm−1, which should be absent from the fully hydrolysed downstream acid if conversion is complete.
Catalytic hydrogenation of benzyl cyanide over Raney cobalt or Raney nickel in the presence of ammonia yields 2-phenylethylamine, a building block for agrochemical and pharmaceutical intermediates. The ammonia is required to suppress secondary and tertiary amine formation. The product distribution shifts to higher amines if the ammonia partial pressure is insufficient or if the reactor temperature is allowed to exceed the recommended window. Raney cobalt generally gives higher primary amine selectivity than Raney nickel in nitrile hydrogenation, but nickel is more common because of lower catalyst cost. Published production-scale data for this specific configuration is limited, but batch hydrogenation vessels can require post-run catalyst filtration and cyanide-leaching checks before disposal.
Acid hydrolysis of benzyl cyanide is usually carried out in mineral acid at elevated temperature. In a typical reaction, the nitrile is charged to 65–70 wt% sulfuric acid and heated at 110–120 °C for several hours. The nitrile band at 2245 cm−1 is monitored by process infrared or grab sample until it no longer appears, after which the mixture is cooled and diluted. Phenylacetic acid is isolated by filtration or solvent extraction, and the aqueous mother liquor contains ammonium sulfate formed from the liberated ammonia. Phenylacetic acid has a melting point near 76.7 °C and a boiling point near 265.5 °C at atmospheric pressure.
Because hot mineral acid and organic nitrile phases are corrosive, glass-lined or tantalum-clad equipment is required; stainless steel may suffer pitting if chloride-containing by-products are present. The conversion is strongly exothermic during initial acid addition, so benzyl cyanide is added to the acid rather than the reverse to limit localized boiling. Residual nitrile in the isolated acid should be controlled because it contributes to colour and off-spec nitrogen content in downstream esterification.
The presence of the benzylic methylene group is the principal structural difference that separates benzyl cyanide from simpler nitriles. This group supplies an α-carbon with substantial C–H acidity, enabling selective deprotonation and alkylation. In contrast, acetonitrile requires much stronger bases for practical alkylation under similar conditions, and benzonitrile lacks an α-methylene entirely. Malononitrile is a stronger carbon acid but generates geminal disubstitution products more readily.
| Property | Benzyl cyanide | Acetonitrile | Benzonitrile | Malononitrile |
|---|---|---|---|---|
| CAS number | 140-29-4 | 75-05-8 | 100-47-0 | 109-77-3 |
| Molar mass | 117.15 g/mol | 41.05 g/mol | 103.12 g/mol | 66.06 g/mol |
| Melting point | -23.8 °C | -45.7 °C | -13 °C | 32 °C |
| Boiling point | 233.5 °C | 81.6 °C | 191 °C | 220 °C |
| Density at 20 °C | 1.015 g/cm³ | 0.786 g/cm³ | 1.010 g/cm³ | 1.049 g/cm³ |
| α-C–H pKa in DMSO | ~21.9 | ~31.3 | Not applicable | ~11.1 |
| Key synthetic behaviour | Monoalkylation at the benzylic carbon; hydrolysis to phenylacetic acid | Very weak carbon acid; mainly used as solvent | No facile α-deprotonation; electrophilic substitution on the ring | Strong carbon acid; forms geminal or heterocyclic products |
These differences affect equipment design as well as chemistry. Acetonitrile is water-miscible and commonly recovered by extractive distillation; benzyl cyanide is not water-miscible and is isolated by phase separation and vacuum distillation. Malononitrile is solid at ambient temperature and requires heated storage or melting systems for bulk transfer, whereas benzyl cyanide remains liquid at ordinary warehouse temperatures. Benzonitrile lacks the reactive α-carbon but has an aromatic nitrile profile suited to high-temperature transformations.
Benzyl cyanide also differs from benzyl chloride as a benzyl source. Benzyl chloride functions primarily as an electrophilic alkylating agent and does not provide the nitrile handle for subsequent hydrolysis or reduction. Benzyl cyanide provides both a nucleophilic α-carbon after deprotonation and a nitrile group that can be hydrolysed to a carboxylic acid or reduced to an amine. In a supply-chain evaluation, benzyl cyanide is selected when the downstream target contains a carboxylic acid, amide, or amine derived from a phenylacetic acid skeleton. Benzyl chloride is selected for direct benzylation of amines or thiols, but its impurity profile includes benzal chloride and toluene, and its hydrolysis product is benzyl alcohol rather than phenylacetic acid.
Compared with phenylacetaldehyde, benzyl cyanide stores the same C8 aromatic skeleton in a less oxidation-prone form. Phenylacetaldehyde can undergo air oxidation to phenylacetic acid and aldol condensation to higher-boiling by-products during storage; benzyl cyanide under nitrogen remains a stable liquid at ambient temperature. This difference is significant in large-scale operation because aldehyde storage often requires inhibited product and close temperature control, while benzyl cyanide can be handled with standard combustible-liquid storage practices if its toxicological hazards are contained.
Because benzyl cyanide is both a reactive organic intermediate and an acutely toxic nitrile, storage and transfer require closed systems with local exhaust ventilation. Bulk storage vessels are typically stainless steel or phenolic-lined carbon steel with nitrogen blanketing; the material should be maintained below 40 °C and away from strong oxidizers, strong bases, and strong acids. Exposure to moisture above the specification limit can promote hydrolysis and generate phenylacetic acid, which may alter subsequent stoichiometry and increase corrosivity. Drummed material is normally topped with dry nitrogen after each withdrawal, and bulk isotanks are dried and pressure-tested before loading.
The compound is classified as toxic if swallowed, in contact with skin, or if inhaled, and carries H301, H311, and H331 hazard statements. Occupational exposure limits are not uniformly established; therefore, closed transfers and air monitoring are used. Carbon-filtration systems on storage vents reduce fugitive emissions. Personnel exposure is controlled with chemical-resistant gloves selected from permeation test data.
Spill response uses inert absorbent; aqueous rinses are collected for cyanide-compatible disposal. Incompatible materials include strong oxidizing agents, which can generate toxic nitrogen oxides, and strong acids or bases, which accelerate hydrolysis or polymerization. Published production-scale failure data for benzyl cyanide storage in specific tank configurations is limited; standard chemical compatibility guides place priority on stainless steel and phenolic-lined carbon steel.
For downstream esterification or hydrogenation, the moisture and chloride limits are more important than the nominal assay alone. A lot at 99.0% assay with 0.15% water may underperform a lot at 98.8% assay with 0.05% water in a sodium amide alkylation because the water destroys the base and changes the heat-release profile. Purchasers therefore request certificates of analysis that include the full impurity profile rather than a single purity value.
