PBTC 50 (Phosphonobutane Tricarboxylic Acid 50%)


Phosphonobutane tricarboxylic acid is excellent as an antiscalant and corrosion inhibitor because of its structural feature of carboxylic acid and phosphoric acid. The PBTC chemical is stable and highly efficient in high hardness, temperature, pH value, and indexed matter concentration.

While usually building with other organophosphates, PBTC acid also widely works together with zinc salts, whose solubility it will increase. For example, phosphonobutane tricarboxylic acid can improve zinc salt solubility. PBTC 50% also have a higher tolerance to oxidation agents like chlorine or bromine.

The first reaction for PBTC 50% production reaction is between dialkyl phosphite (usually dimethyl phosphate in China) and maleic acid dimethyl ester under a basic catalyst. Tetraalkyl ester of phosphonosuccinic acid forms and immediately reacts with methyl acrylate. The following thereupon saponification yields PBTC.

CAS No.:

37971-36-1, from ChemIDplus, EPA Chemicals under the TSCA, EPA DSStox, European Chemicals Agency (ECHA).

40372-66-5, from ChemIDplus, European Chemicals Agency (ECHA).

EC No.:

253-733-5, from the European Chemicals Agency (ECHA).

254-894-4, from the European Chemicals Agency (ECHA).

Molecular Formula:


Molecular Weight:


Structure Formula:

PBTC 50%


AppearanceColorless or light yellow transparent liquid
Active acid, %49.0~51.0
Phosphorous acid (as PO33-), %0.8 Max.
Phosphoric acid (as PO43-), %0.5 Max.
pH (1% water solution)1.5~2.0
Fe, ppm20.0 Max.
Chloride, ppm10.0 Max.
Density (20℃), g/cm31.27 Min.


PBTC 50% is an excellent stabilizer for zinc salt as an excellent inhibitor to both scale and corrosion. It is widely applied in refilling and circulated cooling systems for oil fields, steel mills, and mines. PBTC 50 can be used in situations of high temperature, hardness, alkali, and concentration index.

Besides, phosphonobutane tricarboxylic acid is used to chelate metal ions in lavation and detergent industries as metal detergent. In pH 7~10, 5~15 mg/L is recommended if only PBTC acid. PBTC 50% is usually used with zinc salt, copolymer, organophosphine, imidazole, and other water treatment agents. When used alone, the dosage of 5~15 mg/L is preferred.

Difference between different PBTCA quality assessment methods:

1. Nuclear magnetic resonance carbon spectrum.

The performance of organic compounds is closely related to their structure. Due to the special molecular structure of PBTCA, it performs well in carbon scale inhibition and zinc stabilization.

To study organic compounds’ structure and functional groups, infrared spectroscopy and NMR are the most common and effective means. For example, for the structure identification of PBTCA, NMR carbon spectroscopy is often used because of the high number of carbon atoms in the molecule. In addition, it has the unique advantages of high resolution, simple spectra, and comprehensive information.

2. Nuclear magnetic resonance phosphorus spectroscopy.

During the synthesis of PBTCA, due to the complexity and incompleteness of the organic synthesis reaction, unreacted raw materials and by-products are mixed in the product. Consequently, their scale inhibition and dispersion properties are far from PBTCA.

Their content should be strictly controlled. Using 31P NMR analysis, information on P atoms in the sample can be obtained. The purity of PBTCA in the sample can be indirectly known by calculating the proportion of the P-atom signal on PBTCA to the total P-atom signal. It is generally required to be greater than 80%.

For the quality assessment of PBTCA, combining the means of structural identification with the analysis of physicochemical indexes is necessary. This is the only way to check whether the product quality is qualified. To prevent inferior products from entering the industrial circulating cooling water system. To ensure the safe production of production equipment.

Packing and Storage:

200L plastic drum, IBC (1000L), customers’ requirements.

200L plastic drum 1000L IBC

Storage for one year in a shady room and dry place.

Safety Protection:

Acidity, Avoid contact with eye and skin. Once contacted, flush with water.

Transport Info:

Corrosive. IMO class 8, UN 3265.


PBTC; Dequest 7000; Mayoquest 2100; Bayhibit AM; Belclene 650; Codex 551; Briquest PBTC, PBTC tricarboxylic acid, 2-phosphonobutane-1 2 4-tricarboxylic acid.