Process for producing tetrabromophthalic diesters

A batchwise process for producing a tetrabromophthalic diester composition while recycling solvent and so as to obtain a consistent composition from batch to batch, comprising:

• (a) preparing a first batch by reacting, in an inert organic solvent, tetrabromophthalic anhydride (TBPA), a C.sub.2 to C.sub.6 polyhydric aliphatic alcohol (PAA) and an alkylene oxide (AO) selected from the group consisting of ethylene oxide and propylene oxide, said reacting being in a predetermined PAA:AO:TBPA mole ratio in the range of 1.6-1.9:1.3-1.5:1 and being accomplished by:
• (i) charging to a reactor all TBPA and PAA and only a portion of the the AO necessary to provide the predetermined ratio, and heating and initially reacting this charged mixture to form an initially reacted mixture;
• (ii) charging, in one or more subsequent charges, the remainder of the AO necessary to provide the predetermined ratio and heating and reacting the resulting mixture;
• (iii) after all AO necessary to provide the predetermined ratio has been charged, reacting the resulting mixture at a temperature of about 75.degree. C. to about 150.degree. C. so as to obtain a finally reacted mixture including the tetrabromophthalic diester composition and the organic solvent;
• (b) recovering the organic solvent from the finally reacted mixture by distillation;
• (c) analyzing the recovered organic solvent to determine the level of its AO content;
• (d) preparing a second batch by repeating step (a) above wherein the organic solvent used includes the recovered organic solvent and wherein its determined AO level is accounted for to ensure that essentially the same PAA:AO:TBPA molar ratio is reacted in preparing the first and second batches.

A batchwise process for producing a consistent tetrabromophthalic diester composition, comprising:

• (a) reacting tetrabromophthalic anhydride (TBPA), diethylene glycol (DEG) and propylene oxide (PO) in an inert aromatic solvent in a DEG:PO:TBPA mole ratio of about 1.6-1.9:1.3-1.5:1 to obtain a reacted mixture including the tetrabromophthalic diester composition and the aromatic solvent;
• (b) recovering the aromatic solvent from the reacted mixture by distillation;
• (c) determining the PO content of the recovered aromatic solvent;
• (d) repeating step (a) wherein the aromatic solvent used includes the recovered aromatic solvent and wherein its PO content is accounted for in achieving the DEG:PO:TBPA mole ratio.