N-Butylbenzenesulfonamide (commonly abbreviated as NBBS or BBSA) is an organic sulfonamide compound with the chemical formula C₁₀H₁₅NO₂S and a molecular weight of 213.30 g/mol. It contains a benzene ring linked via a sulfonyl (–SO₂–) group to an N-butylamine moiety. The compound is primarily used industrially as a plasticizer and chemical intermediate and has important safety and toxicological considerations.

Chemical Structure and Nomenclature

• IUPAC name: N-Butylbenzenesulfonamide

• CAS Number: 3622-84-2

• Synonyms: N-n-Butylbenzenesulfonamide, N-Butyl benzene sulphonamide, N-BBSA, BBSA

Structurally, NBBS consists of a benzenesulfonamide core (a benzene ring attached to a sulfonamide group) with a linear butyl chain (–CH₂CH₂CH₂CH₃) on the nitrogen atom. This arrangement gives the molecule both aromatic character and lipophilic alkyl chain features, influencing its reactivity, solubility, and physical properties.

Physical and Chemical Properties

Physical State and Appearance

• At ambient temperatures, NBBS is a colorless to pale straw-colored liquid with a slight odor.

Density

• Approximately 1.15 g/mL at 25 °C.

Melting and Boiling Points

• Melting Point: ~83 °C (in solvents like ethanol or water).

• Boiling Point: ~314 °C (literature value).

Refractive Index

• n²⁰ᴰ ≈ 1.525 (lit.).

Vapor Pressure

• Low, around 0.35 mm Hg at 150 °C.

Solubility

• Slight solubility in organic solvents such as chloroform and methanol; limited solubility in water.

pKa

• Predicted pKa of approximately 11.6, typical for sulfonamide‐type N–H acidity.

The combination of a bulky aromatic group and the butyl side chain contributes to NBBS’s moderate polarity, low water solubility, and relatively high thermal stability for an organic additive.

Industrial and Technical Uses

Plasticizer in Polymer Manufacturing

The major industrial application of NBBS is as a plasticizer, where it is added to polymers such as nylons (e.g., Nylon 11 & Nylon 12), polyacetals, polycarbonates, cellulose resins, hot-melt adhesives, and flexible tubing to enhance mechanical flexibility, processability, and surface characteristics.

Plasticizers like NBBS intercalate between polymer chains, reducing intermolecular forces and increasing material ductility and impact resistance without severely compromising strength. This makes them valuable in engineering Plastics and specialty coatings.

Chemical Intermediate

NBBS can serve as a precursor or intermediate in the synthesis of other sulfonamide derivatives or functionalized organic molecules in fine chemical and materials research. The sulfonamide functional group participates in various organic reactions, particularly nucleophilic substitution and amide formation pathways.

Chemical Reactivity

Functional Group Behavior

• The sulfonamide group (–SO₂NH–) is relatively stable but can undergo substitution reactions at the sulfur or nitrogen under appropriate conditions.

• The butyl side chain is typical of aliphatic amines and can engage in typical N-alkylation or oxidation reactions under strong reagents.

Unlike more reactive functional groups like aldehydes or acid chlorides, NBBS’s core sulfonamide group is typically inert under mild conditions, which is why it is suitable as a stable additive.

Safety and Toxicology

Human Health Hazards

NBBS is classified as an irritant:

• Can cause eye, skin and respiratory tract irritation.

• Chronic exposure may lead to organ toxicity through repeated exposure.

Acute toxicity data suggest:

• Oral LD50 (rat): ~2050 mg/kg

• Oral LD50 (mouse): ~2500 mg/kg

These values indicate low to moderate acute toxicity on ingestion.

Neurotoxicity Findings

Animal studies have reported neurotoxic effects following repeated high-dose exposures, including motor dysfunction and structural neuronal changes, highlighting the need for careful exposure control in laboratory and industrial settings.

Environmental Impact

• Classified as harmful to aquatic life with long-lasting effects.

• Proper waste disposal and spill containment are important to avoid environmental release.

Handling and PPE

Standard industrial and laboratory precautions apply:

• Use in a well-ventilated area

• Wear protective gloves, goggles, and lab coat

• Avoid inhalation of vapors and contact with skin or eyes

Regulatory Considerations

NBBS is recognized under chemical inventory and regulatory frameworks such as:

• TSCA (Toxic Substances Control Act) in the United States.

Due to its classification hazards, NBBS is typically subject to workplace exposure limits, labeling requirements, and careful environmental discharge controls.

N-Butylbenzenesulfonamide is a sulfonamide with valuable industrial uses, particularly as a plasticizer in high-performance polymers. Its physicochemical profile, thermal stability, and functional group characteristics make it an effective additive for improving polymer flexibility. However, its health and ecological risks require adherence to safety protocols in handling and disposal.