Synthesis and properties of 4‐hydroxy‐2,3,5,6‐tetrabromobenzyl phosphonates and effects of their flame retardance on impact polystyrene

Abstract

Synopsisp-Cresol was converted into 2,3,5,fXetrabromocresol by A1C13 catalyst bromination, and then further brominated to 4-hydroxy-2,3,5,6-tetrabromobenzyl bromide (HTBBB) in benzene by light. HTBBB reacted easily with trialkyl phosphite to produce 4-hydroxy-2,3,5,6-tetrabromobenzyl phosphonates (HTBBPs) in solvents. Although the reaction of HTBBB with triaryl phosphite was slower than that with trialkyl phosphite, it does produce corresponding phosphonate with ease. Except for DMF, DMAc, chloroform, and tetrahydrofuran, HTBBP was difficult to dissolve in ordinary organic solvents. Of all the synthesized HTBBP, dimethyl hydroxy-2,3,5,6-tetrabromobenzyl phosphonate showed the poorest solubility. With the addition of these new compounds containing bromine and phosphorus atoms to HIPS as flame retardants, the results of oxygen index measurement showed that the flame resistance of these compounds was greater than the additive effect of the two corresponding individual brominated compound and phosphoruscontaining compound. It means that these new compounds seem to act synergistically as flame retardants in HIPS. Simultaneous addition of bominated compound and phosphoruscontaining compound to HIPS ends up with a similar effect as mentioned above, but the new compounds can prevent the exclusion of phosphoruscontaining compound from polymer matrix.

Phosphorus-Bromine Flame Retardant Synergy in a Polycarbonate/Polyethylene Terephthalate Blend

“…However, a mixture of BrPC and TTP with a composition of 6% bromine and 0.4% phosphorus gave an oxygen index value significantly higher than anticipated (Figure 4). When bromine and phosphorus are in the same compound, as in the brominated phosphate, an even higher value was obtained consistent with the reports of Yang and Lee [5][6][7]. These data suggest that bromine and phosphorus are synergistic in this polymer blend.…”

“…When phosphorus and bromine are in the same molecule even higher oxygen indices were obtained. These data convincingly show phosphorus/bromine synergy [5]. Similar synergy was shown in high impact polystyrene (HIPS) and polymethyl I methacrylate [6,7].…”

The influence of an N-alkoxy HALS on the decomposition of a brominated fire retardant in polypropylene

“…Antimony trioxide (Sb 2 O 3 ) has been the most commonly used synergist for brominated fire retardants and its behaviour has been well articulated by many researchers [4,7,8]. Phosphorous can also be used to enhance the fire retardant activity of brominated fire retardants [9]. However unlike Sb 2 O 3 , phosphorus can exist in the same molecule with bromine and these fire retardant additives have been shown to enhance the phosphorusebromine synergism [5].…”

Structural Basis for Intumescence – Part III – Thermal Degradation Study of Intumescent Polymers Containing Spirophosphorus Moiety in the Backbone

“…Elemental red phosphorus [1][2][3] , water-soluble inorganic phosphates, insoluble ammonium polyphosphates [4][5][6] , organophosphates and phosphonates [7] , phosphine oxides [8][9][10] and chloro aliphatic and bromo aromatic phosphates [11][12][13][14] are the diverse phosphorus containing chemicals widely used in polymers as flame retardants. These chemicals having different chemical properties function differently in their flame-retardant mechanism [15][16][17] .…”