TRIBUTOXYETHYL PHOSPHATE (TBEP)

Introduction

Tributoxyethyl phosphate, also known as TBEP and tris(2-butoxyethyl) phosphate, is an organophosphate ester used primarily as a plasticizer and flame retardant. As discussed earlier, it is the same compound as tri butoxyethyl phosphate and tri(2-butoxyethanol) phosphate.

It is not a direct food additive. Its relevance to food chemistry is through its role as an indirect food additive, where it may be present as a component of adhesives, coatings, or plastics that come into contact with food. It helps provide flexibility and durability to these materials. Its use in food contact materials is regulated to prevent unsafe migration into food.

CAS Number

78-51-3

Synonyms

• TBEP
• Tris(2-butoxyethyl) phosphate
• Tri(butoxyethyl)phosphate
• Phosphoric acid, tris(2-butoxyethyl) ester
• KP-140
• Kronitex KP-140

Topic Headings

1. Primary Industrial Applications (list form)

• Plasticizer — Used in the production of flexible PVC, adhesives, and coatings, including those used on food packaging.
• Flame retardant — Added to a wide range of materials to reduce their flammability.
• Leveling agent — Used in paints, varnishes, and printing inks to promote an even and consistent finish.
• Wetting agent — Improves the spreading properties of liquids on surfaces in various industrial processes.
• Hydraulic fluid component — Used as an additive in some specialized industrial hydraulic fluids.

2. Mechanism of Action as a Plasticizer (paragraph form)

As a plasticizer, TBEP functions by embedding itself between the polymer chains of a rigid material. Its relatively bulky, flexible molecule acts as an internal lubricant, increasing the free volume and reducing the intermolecular forces holding the polymer chains together. This allows the chains to slide past each other more easily, thereby increasing the material's flexibility, workability, and resistance to shattering. The effect is a significant reduction in the material's glass transition temperature (Tg).

3. Physical and chemical properties (list form)

• Appearance — Clear, colorless to pale yellow viscous liquid.
• Odor — Mild, characteristic odor.
• Molecular weight — 398.47 g/mol.
• Boiling point — Decomposes at elevated temperatures.
• Viscosity — High (approx. 12-15 cP at 25°C).
• Water solubility — Very low (approx. 0.1-1.0 g/100 mL).
• Density — Approximately 1.02 g/cm³ at 25°C.
• Refractive index — Approximately 1.438 at 20°C.

4. Safety and Regulatory Status (paragraph form)

The substance is regulated as an indirect food additive by the FDA and may be used in food contact materials subject to specific restrictions. It is listed in the FDA's Inventory of Food Contact Substances and is also regulated as a component of adhesives. When used as a plasticizer in food packaging, manufacturers must ensure that the final food contact material complies with migration limits. While it is of low acute toxicity, some studies have reported potential endocrine-disrupting effects in aquatic life, leading to environmental restrictions. It is not approved for direct addition to food.