Chemicals Based Technologies - Tetrabromobisphenol-A

Introduction

By the end of twentieth century, synthetic polymers have phenomenally attracted the global attention. Simultaneously, the application of various flame retardant materials has also been established. Approximately ten percent of total polymers have been identified as flame-retardants. Flame-retardants are simply the halogenated organic compounds. Brominated or chlorinated compounds are chiefly used as flame-retardants. They are used in the manufacture of plastics, electrical and electronic products, laminates, adhesives etc. which when incidentally caught fire, flame retardant releases halogen hydrides and extinguish the fire. Tetrabromobisphenol-A (CH3 ) C (C6 H2 Br2 OH) 2 (79-94-7) denoted hereafter as TBBPA, is one such flame-retardant. It is a bromine derivative of bisphenol-A and TBBPA is an important substance among various bromo compounds. As a flame retardant, TBBPA constitutes on-third of the total bromine based flame-retardants because of its high stability and compatibility as an additive and a reactive compound. TBBPA is also used in the preparation of acrylonitrile butadiene styrene (ABS) polymer as well as in the preparation of epoxy and polycarbonate resins. These resins have versatile applications in the manufacture of electronic equipment, in particular computer-printed circuit boards. The resins are also used as fire retardants in the manufacture of coatings, plastics, paints, adhesives and laminates as the high level activity of TBBPA allows it to be used at relatively low loading, transulating to a greater retention of the physical properties of the base polymer. The survey carried out by Chemical Weekly in 1994 revealed an overall (5-6%) growth in the use of TBBPA.

According to the survey conducted in 1993, the total global annual production of bromine was estimated to be about 1.70 lakh tons and about 47% of it had been consumed in the production of fire retardants only. TBBPA and tetrabromodiphenyl ether are being used worldwide as potential fire retardants. Considering that 20% of total world’s bromine production goes into the manufacture of these compounds, their annual production has been estimated to be around 0.60 lakh tons. The bromine production during 1995-2000 in India was found to be around 2000-2200 tons over and above that of 500-750 tons was imported. Although, bromine also finds many applications in the manufacture of dyes and drug intermediates, if one assumes similar trend of bromine consumption as it prevails the world over, it is expected that the requirement of TBBPA is about 1000 tons per year in India.

Only a few organized sectors in Indian Industry are manufacturing TBBPA. Companies like i) M/s Nerka Chemicals Pvt.Ltd., Vapi; ii) M/s Sky Lead Chemicals, Bhavnagar; iii) M/s Alkyl Chemicals, Valsad and iv) M/s Kesar Petro Products, Mumbai had been known in the past to manufacture TBBPA from liquid bromine in a small scale which was stopped later on for unknown reason. One of them could be due to low bromine atom efficiency of the process. The capacity of these units and their actual production figures are not even known as such. Under these circumstances, it seems that the market for the manufacture of TBBPA would attract many entrepreneurs.

Process

Bisphenol-A (BPA) is suspended in a chlorinated organic solvent in a two neck round bottom flask. Required amount of the brominating agent, developed by this institute for substitution reaction, dissolved in water was added to it. Calculated volumes of commercial grade hydrochloric acid is added drop wise over 3 h under stirring. After the addition, the contents are stirred for half-an hour more for the reaction to complete. The crystallized product is filtered, washed with water and dried in oven. The organic layer is recycled for the successive batch by recharging BPA, brominating agent and acid. After the completion of a number of cycles, the organic solvent is distilled out to separate the solvent and the product dissolved in it. The aqueous layer contains excess unreacted acid and inorganic salts, which can be discharged after neutralization.

Specifications of the Product

The dried TBBPA will have the following characteristics :

Raw Material and Utility Requirement

• Bisphenol - A
  
• Brominating agent
  
• Halogenated organic solvent
  
• Mineral acid
  
• Deionized water
  
• Alkali
  
• Chlorine
  

List of Major Equipments

• Glass or glass lined reactors with accessories like stirrers, motors, rpm control, distillation assembly etc.
  
• Separating funnels,
  
• Filtration unit
  
• Oven
  
• Pumps
  

Economic Aspects of the Product

Raw material and utility cost has been calculated base don the data collected for the preparation of 1 kg of TBBPA and the cost figures available from Chemical Weekly are given in the following table.

Raw materials cost in the preparation of 1 kg of TBBPA using New Brominating agent developed in this laboratory :-

For further information please contact :

National Research Development Corporation
( A Government of India Enterprise )
20-22, Zamroodhpur Community Center
Kailash Colony Extension
New Delhi 110 048. India
Tel: 91-11-26419904, 26417821, 26480767, 26432627
Fax: 011-26231877, 26460506, 26478010
Website: www.nrdcindia.com

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