Bisphenol C Research Articles

Differential activity of BPA, BPAF and BPC on zebrafish estrogen receptors in vitro and in vivo

The high volume production compound bisphenol A (BPA) is of environmental concern largely because of its estrogenic activity. Consequently, BPA analogues have been synthesized to be considered as replacement molecules for BPA. These analogues need to be thoroughly evaluated for their estrogenic activity. Here, we combined mechanism zebrafish-based assays to examine estrogenic and anti-estrogenic activities of BPA and two of its analogues, bisphenol AF (BPAF) and bisphenol C (BPC) in vitro and in vivo. In vitro reporter cell lines were used to investigate agonistic and antagonistic effects of the three bisphenols on the three zebrafish estrogen receptors. The transgenic Tg(5 × ERE:GFP) and Cyp19a1b-GFP zebrafish lines were then used to analyze estrogenic and anti-estrogenic responses of the three bisphenols in vivo. BPA, BPAF and BPC were agonists with different potencies for the three zebrafish estrogen receptors in vitro. The potent zfERα-mediated activity of BPA and BPAF in vitro resulted in vivo by activation of GFP expression in zebrafish larvae in the heart (zfERα-dependent) at lower concentrations, and in the liver (zfERβ-dependent) at higher concentrations. BPC induced zfERβ-mediated luciferase expression in vitro, and the zfERβ agonism led to activation of GFP expression in the liver and the brain in vivo. In addition, BPC acted as a full antagonist on zfERα, and completely inhibited estrogen-induced GFP expression in the heart of the zebrafish larvae. To summarize, applying a combination of zebrafish-based in vitro and in vivo methods to evaluate bisphenol analogues for estrogenic activity will facilitate the prioritization of these chemicals for further analysis in higher vertebrates as well as the risk assessment in humans.

Characterization of Estrogenic and Androgenic Activities for Bisphenol A-like Chemicals (BPs): In Vitro Estrogen and Androgen Receptors Transcriptional Activation, Gene Regulation, and Binding Profiles.

Bisphenol A (BPA) is a high production volume chemical widely used in plastics, food packaging, and many other products. It is well known that endocrine-disrupting chemicals might be harmful to human health due to interference with normal hormone actions. Recent studies report widespread usage and exposure to many BPA-like chemicals (BPs) that are structurally or functionally similar to BPA. However, the biological actions and toxicity of those BPs are still relatively unknown. To address this data gap, we used in vitro cell models to evaluate the ability of 22 BPs to induce or inhibit estrogenic and androgenic activity. BPA, Bisphenol AF (BPAF), bisphenol Z (BPZ), bisphenol C (BPC), tetramethyl bisphenol A (TMBPA), bisphenol S (BPS), bisphenol E (BPE), 4,4-bisphenol F (4,4-BPF), bisphenol AP (BPAP), bisphenol B (BPB), tetrachlorobisphenol A (TCBPA), and benzylparaben (PHBB) induced estrogen receptor (ER)α and/or ERβ-mediated activity. With the exception of BPS, TCBPA, and PHBB, these same BPs were also androgen receptor (AR) antagonists. Only 3 BPs were found to be ER antagonists. Bisphenol P (BPP) selectively inhibited ERβ-mediated activity and 4-(4-phenylmethoxyphenyl)sulfonylphenol (BPS-MPE) and 2,4-bisphenol S (2,4-BPS) selectively inhibited ERα-mediated activity. None of the BPs induced AR-mediated activity. In addition, we identify that the BPs can bind to ER or AR with varying degrees by a molecular modeling analysis. Taken together, these findings help us to understand the molecular mechanism of BPs and further consideration of their usage in consumer products.

Minor structural modifications of bisphenol A strongly affect physiological responses of HepG2 cells

Bisphenols represent a large group of structurally similar compounds. In contrast to bisphenol A (BPA) and bisphenol S (BPS), however, toxicological data are usually scarce, thus making bisphenols an ideal candidate for read-across assessments. BPA, bisphenol C (BPC) and a newly synthesized bisphenol A/C (BPA/C) differ only by one methyl group attached to the phenolic ring. Their EC50 values for cytotoxicity and logPOW values are comparable. However, the estrogenic activities of these bisphenols are not comparable and among this group only BPC leads to a decrease of the mitochondrial membrane potential and ATP concentration in HepG2 cells. Conversely, the cell division rate was decreased by BPS, BPA, BPC and BPA/C at 10% toxicity (EC10). At lower concentrations, only BPC significantly affected proliferation. The pro-inflammatory cytokines TGFB1 and TNF were significantly upregulated by BPC only, while SPP1 was upregulated by BPA, BPA/C and BPS. BPC led to the release of cytochrome c from mitochondria, indicating that this compound is capable of inducing apoptosis. In conclusion, the read-across approach revealed non-applicable in the case of the various structurally and physicochemically comparable bisphenols tested in this study, as the presence of one or two additional methyl group(s) attached at the phenol ring profoundly affected cellular physiology.

A Conflicted Tale of Two Novel AR Antagonists In Vitro and In Vivo: Pyrifluquinazon Versus Bisphenol C.

Chemicals that disrupt androgen receptor (AR) function in utero induce a cascade of adverse effects in male rats including reduced anogenital distance, retained nipples, and reproductive tract malformations. The objective of this study was to compare the in vitro and in utero activities of two novel AR antagonists, bisphenol C (BPC) and pyrifluquinazon (PFQ). In vitro, BPC was as potent an AR antagonist as hydroxyflutamide. Furthermore, BPC inhibited fetal testis testosterone production and testis gene expression ex vivo. However, when BPC was administered at 100 and 200 mg/kg/d in utero, the reproductive tract of the male offspring was minimally affected. None of the males displayed reproductive malformations. For comparison, in utero administration of flutamide has been shown to induce malformations in 100% of males at 6 mg/kg/d. In vitro, PFQ was several orders of magnitude less potent than BPC, vinclozolin, or procymidone. However, in utero administration of 12.5, 25, 50, and 100 mg PFQ/kg/d on GD 14-18 induced antiandrogenic effects at all dosage levels and 91% of the males displayed reproductive malformation in the high dose group. Overall, BPC was ∼380-fold more potent than PFQ in vitro, whereas PFQ was far more potent than BPC in utero. Incorporating toxicokinetic and toxicodynamic data into in vitro to in vivo extrapolations would reduce the discordance between the in vitro and in utero effects of PFQ and BPC and combining in vitro results with a short-term Hershberger assay would reduce the uncertainty in predicting the in utero effects of antiandrogenic chemicals.

A Novel Action of Endocrine-Disrupting Chemicals on Wildlife; DDT and Its Derivatives Have Remained in the Environment.

Huge numbers of chemicals are released uncontrolled into the environment and some of these chemicals induce unwanted biological effects, both on wildlife and humans. One class of these chemicals are endocrine-disrupting chemicals (EDCs), which are released even though EDCs can affect not only the functions of steroid hormones but also of various signaling molecules, including any ligand-mediated signal transduction pathways. Dichlorodiphenyltrichloroethane (DDT), a pesticide that is already banned, is one of the best-publicized EDCs and its metabolites have been considered to cause adverse effects on wildlife, even though the exact molecular mechanisms of the abnormalities it causes still remain obscure. Recently, an industrial raw material, bisphenol A (BPA), has attracted worldwide attention as an EDC because it induces developmental abnormalities even at low-dose exposures. DDT and BPA derivatives have structural similarities in their chemical features. In this short review, unclear points on the molecular mechanisms of adverse effects of DDT found on alligators are summarized from data in the literature, and recent experimental and molecular research on BPA derivatives is investigated to introduce novel perspectives on BPA derivatives. Especially, a recently developed BPA derivative, bisphenol C (BPC), is structurally similar to a DDT derivative called dichlorodiphenyldichloroethylene (DDE).

New insights into bisphenols removal by nitrogen-rich nanocarbons: Synergistic effect between adsorption and oxidative degradation

In this work, nitrogen-rich graphene-like carbon sheets (N-GLCS) with high specific surface area (488.4m2/g), narrow pore distribution and high N-doping (18.4 at%) were prepared and applied as both adsorbent and catalyst for the removal of bisphenols. Adsorption experiments demonstrated the high adsorption capacities of the N-GLCS toward bisphenol F (BPF) (222.9mg/g), bisphenol A (BPA) (317.8mg/g), and bisphenol C (BPC) (540.4mg/g). Results showed that about 98.6% of BPA (70mg/L) was removed at pH 7.0 within 80min after the adsorption-catalytic degradation process. The N-GLCS also showed a superb reusability for the catalytic oxidative degradation of BPA (70mg/L) with the removal percentage maintains over 83% after 5 cycles. With the synergistic combination of the excellent adsorption and catalytic properties of the N-GLCS, trace amount of pollutants can be preconcentrated and immobilized at the surface of N-GLCs, at the same time, active radicals were also produced at the surface of the N-GLCS by the activation of peroxydisulfate (PS), and finally the pollutants can be degraded in-situ by the active radicals. These findings provide a new avenue towards the efficient removal of trace-level EDCs from water solution by using the coupled adsorption-advanced oxidation processes.

The occurrence and source identification of bisphenol compounds in wastewaters

This study reports the occurrence of eight bisphenols (BPs): bisphenol AF (BPAF), bisphenol AP (BPAP), bisphenol B (BPB), bisphenol C (BPC), bisphenol E (BPE), bisphenol F (BPF), bisphenol S (BPS) and bisphenol Z (BPZ) in wastewaters (WWs). Sample preparation involved pre-concentration with SPE cartridges (Oasis HLB), followed by derivatization using N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide with 1% tert-butyldimethylchlorosilane. Chemical analysis was based on gas chromatography–mass spectrometry. A validated method with limits of detection (LODs) at ngL−1 range was applied to WWs collected at five Slovene wastewater treatment plants (WWTPs) and WW inflows from industrial, commercial and residential sources entering the sewerage systems of two catchments (Domžale-Kamnik (DK) and Ljubljana (LJ)). The presence of all BPs was confirmed in three inflows in DK and two inflows in the LJ catchments. High cumulative concentrations of all BPs were determined in WW from food processing facilities (LJ: 3030ngL−1 and DK: 599ngL−1). A high detection frequency was observed in the WW from two textile cleaning companies (6 BPs for LJ and 8 BPs for DK). The analysis of WW from WWTPs revealed that only BPF (36.7ngL−1) and BPS (40.6ngL−1) were >LODs in the influents, whereas other BPs were detected also in the effluents. BPZ was found in the highest concentration (403ngL−1 at WWTP-DK). WW collected at this WWTP also contained the highest amount of BPE (238ngL−1). Although BPs removal could not be directly compared between the WWTPs, with the exception of BPAP and BPB in the case of two smaller WWTPs (6.39%–43.2%) bisphenols were in general highly removed (≥96.2%). Finally, levels of BPC>LOD are reported for first time (WWTP in the DK catchment: 1.01ngL−1–11.8ngL−1; LJ inflow from food processing plant up to 2560ngL−1).

A dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by injector port silylation coupled with gas chromatography–tandem mass spectrometry for the determination of nine bisphenols in bottled carbonated beverages

In the present study, a method has been efficiently developed for the first time to determine nine bisphenol analogues [bisphenol A (BPA), bisphenol C (BPC), bisphenol AF (BPAF), bisphenol E (BPE), bisphenol F (BPF), bisphenol G (BPG), bisphenol M (BPM), bisphenol S (BPS), and bisphenol Z (BPZ)] together in bottled carbonated beverages (collected from the local market of Lucknow, India) using dispersive liquid-liquid microextraction process. This is based on solidification of floating organic droplet (DLLME-SFO) followed by injector port silylation coupled with gas chromatography–tandem mass spectrometry. The process investigated parameters of DLLME-SFO (including the type of extraction and disperser solvents with their volumes, effect of pH, ionic strength, and the sample volume), factors influencing to injection port derivatization like, collision energy, injector port temperature, derivatizing reagent with sample injection volume, and type of organic solvent. BPA, BPF, BPZ, and BPS were detected in each sample; whereas, other bisphenols were also detected in some carbonated beverage samples. After optimizing the required conditions, good linearity of analytes was achieved in the range of 0.097–100ngmL−1 with coefficients of determination (R2)≥0.995. Intra-day and inter day precision of the method was good, with relative standard deviation (% RSD)≤10.95%. The limits of detection (LOD) and limits of quantification (LOQ) values of all bisphenols were ranged from 0.021 to 0.104ngmL−1 and 0.070 to 0.343ngmL−1, respectively. The recovery of extraction was good (73.15–95.08%) in carbonated beverage samples and good enrichment factors (96.36–117.33) were found. Thus, the developed method of microextraction was highly precise, fast, and reproducible to determine the level of contaminants in bottled carbonated beverages.

Bioaccumulation and biomagnification of emerging bisphenol analogues in aquatic organisms from Taihu Lake, China

Due to regulations on bisphenol A (BPA) in many countries, a variety of bisphenol analogues are being widely manufactured and applied. However, there is a big knowledge gap on bioaccumulation and biomagnification of these emerging bisphenols in aquatic organisms. The bioaccumulation and magnification of nine bisphenol analogues in aquatic organisms at different trophic levels collected from Taihu Lake, China, were evaluated. The total concentrations of the nine bisphenols in the lake waters were in the range of 49.7–3480ng/L (mean, 389ng/L). BPA, bisphenol AF (BPAF) and bisphenol S (BPS) were the most predominant analogues in the water. The mean natural logarithm bioaccumulation factor (log BAFs) of BPAF, bisphenol C (BPC), bisphenol Z (BPZ) and bisphenol E (BPE) were greater than BPA, and there was a significantly positive correlation between log BAFs of the biphenols and their octanol-water partition coefficients (log Kow). The trophic magnification factors of BPAF, BPC and BPZ were 2.52, 2.69 and 1.71, respectively, suggesting that they had the potential to biomagnify in the food web. The results of this study call for further investigations on risk assessment of these emerging pollutants in the environment.

A Demonstration of the Uncertainty in Predicting the Estrogenic Activity of Individual Chemicals and Mixtures From an In Vitro Estrogen Receptor Transcriptional Activation Assay (T47D-KBluc) to the In Vivo Uterotrophic Assay Using Oral Exposure.

In vitro estrogen receptor assays are valuable tools for identifying environmental samples and chemicals that display estrogenic activity. However, in vitro potency cannot necessarily be extrapolated to estimates of in vivo potency because in vitro assays are currently unable to fully account for absorption, distribution, metabolism, and excretion. To explore this issue, we calculated relative potency factors (RPF), using 17α-ethinyl estradiol (EE2) as the reference compound, for several chemicals and mixtures in the T47D-KBluc estrogen receptor transactivation assay. In vitro RPFs were used to predict rat oral uterotrophic assay responses for these chemicals and mixtures. EE2, 17β-estradiol (E2), benzyl-butyl phthalate (BBP), bisphenol-A (BPA), bisphenol-AF (BPAF), bisphenol-C (BPC), bisphenol-S (BPS), and methoxychlor (MET) were tested individually, while BPS + MET, BPAF + MET, and BPAF + BPC + BPS + EE2 + MET were tested as equipotent mixtures. In vivo ED50 values for BPA, BPAF, and BPC were accurately predicted using in vitro data; however, E2 was less potent than predicted, BBP was a false positive, and BPS and MET were 76.6 and 368.3-fold more active in vivo than predicted from the in vitro potency, respectively. Further, mixture ED50 values were more accurately predicted by the dose addition model using individual chemical in vivo uterotrophic data (0.7-1.5-fold difference from observed) than in vitro data (1.4-86.8-fold). Overall, these data illustrate the potential for both underestimating and overestimating in vivo potency from predictions made with in vitro data for compounds that undergo substantial disposition following oral administration. Accounting for aspects of toxicokinetics, notably metabolism, in in vitro models will be necessary for accurate in vitro-to-in vivo extrapolations.

A novel mechanism of conjugate formation of bisphenol A and its analogues by Bacillus amyloliquefaciens: Detoxification and reduction of estrogenicity of bisphenols

A bacterial strain with the ability to transform bisphenol A (BPA) and other so-called “new-generation bisphenols” like bisphenol C (BPC), bisphenol E (BPE), bisphenol F (BPF) and bisphenol Z (BPZ) was isolated from sewage sludge and identified as Bacillus amyloliquefaciens. We investigated the biotransformation of bisphenols and analyzed the toxicity and estrogenicity of the products formed compared to the parent compounds. During the incubation of this bacterial strain with different bisphenols one major metabolite was detected in each case by HPLC but its formation was partly reversible. Highest transformation rate of 77% of the initial concentration applied was determined for BPA and BPE. Mass spectrometric and nuclear magnetic resonance spectroscopic analyses as well as deconjugation experiments proofed the formation of phosphate conjugates with each bisphenol. The conjugates formed were considerably less toxic and less estrogenically active than their parent bisphenols.

Preparation and Characterization of Bisphenol A Molecularly Imprinted Silica Nanospheres

Molecularly imprinted polymers of bisphenol A were synthesized with a sol-gel process on the supporter of silica nanospheres. The BPA-imprinted silica nanospheres were characterized by scanning electron microscope, dynamic adsorption, static adsorption tests and molecular selectivity tests. Scatchard analysis revealed that two classes of binding sites were formed in the imprinted polymers, the equilibrium association constant and the apparent maximum number of binding sites were estimated to be 0.20 μmol•ml-1 and 137.55 μmol•g-1, respectively. Bisphenol A and three analogues, tetrabromobisphenol A (TBBPA), bisphenol C (BPC) and nonylphenol (NP) were employed for selectivity tests. The results indicated that the imprinted polymers exhibited excellent selectivity and specificity toward bisphenol A.

Structural and mechanistic insights into bisphenols action provide guidelines for risk assessment and discovery of bisphenol A substitutes

Bisphenol A (BPA) is an industrial compound and a well known endocrine-disrupting chemical with estrogenic activity. The widespread exposure of individuals to BPA is suspected to affect a variety of physiological functions, including reproduction, development, and metabolism. Here we report that the mechanisms by which BPA and two congeners, bisphenol AF and bisphenol C (BPC), bind to and activate estrogen receptors (ER) α and β differ from that used by 17β-estradiol. We show that bisphenols act as partial agonists of ERs by activating the N-terminal activation function 1 regardless of their effect on the C-terminal activation function 2, which ranges from weak agonism (with BPA) to antagonism (with BPC). Crystallographic analysis of the interaction between bisphenols and ERs reveals two discrete binding modes, reflecting the different activities of compounds on ERs. BPA and 17β-estradiol bind to ERs in a similar fashion, whereas, with a phenol ring pointing toward the activation helix H12, the orientation of BPC accounts for the marked antagonist character of this compound. Based on structural data, we developed a protocol for in silico evaluation of the interaction between bisphenols and ERs or other members of the nuclear hormone receptor family, such as estrogen-related receptor γ and androgen receptor, which are two known main targets of bisphenols. Overall, this study provides a wealth of tools and information that could be used for the development of BPA substitutes devoid of nuclear hormone receptor-mediated activity and more generally for environmental risk assessment.

Development and Characterization of Novel Fore Safe Epoxy Resins

The curing system for newly developed solid state fire safe epoxy resins using dicyandiamide (DICY) was introduced. Composites of epoxy resins obtained from diglycidyl ether of 1,1-dichloro-2,2bis(4-hydroxyphenyl)ethylene bisphenol-C (BPC) and bisphenol-A (BPA) epoxy resins in the reaction with BPC and BPA and DICY hardener were studied. Solid epoxy resins were synthesised by the use of two different heating methods: conventional and microwave reactor. The quantities of DICY additions were 0.5–5.0 %, optimum was found to be 3 %. Limited oxygen index (OI) tests for different epoxy resins and addition of flame – retardants were carried out. The highest value of OI was 34.6. As additional flame-retardants were used zinc stannates (ZS, ZHS). Evident OI increase was noted from 27.0 for classical epoxies, 34.6 for BPC cured epoxies and 44 for cured composites with the addition of Zn/Sn flame-retardants.

Synthesis and Characterization of Linear Homopolyesters Containing s-Triazine Rings

Eight homopolyesters were synthesized by high temperature polycondensation of 2-(N-1-naphthylamine)-4,6-bis (naphthoxy-2-carbonyl chloride)-s-triazine [NANCCT]with each of the eight diols: Bisphenol-A(BPA), bisphenol-C(BPC), phenolphthalein(ph), resorcinol(R), hydroquinone(Hq), catechol(C), 1,5-dihydroxy naphthalene (1, 5-DHN), and ethylene glycol (EG). All the polyesters were characterized by solubility, density, viscosity measurements, IR spectra, NMR spectroscopy, and thermogravimetric analysis.

Synthesis and characterisation of polyesters based on s-triazine

Various polyesters were synthesised by stirred interfacial polycondensation of 2-( N-piperidine)-4,6-bis-(naphthoxy-3-carbonylchloride)- s-triazine (PNCCT) with each of the aromatic and aliphatic diols: bisphenol-A (BPA), bisphenol-C (BPC), bisphenol-S (BPS), phenolphthalein (Ph), catechol (C), resorcinol (R), hydroquinone (Hq), ethylene glycol (EG), and 1,4-butanediol (Bu-1,4). Interfacial polycondensation of PNCCT with BPA was investigated in detail in order to select optimum reaction conditions. The yield of polyesters varies from 63 to 76%. The polyesters are soluble in methylated solvents such as dimethyl formamide, dimethyl sulfoxide, methanol etc. The reduced viscosity for polyesters, determined with a 1 g/dl solution in dimethyl formamide at 25±3°C was found to be in the range 0.340–0.628 dl/g. All the polyesters were characterised by IR spectra. The densities of the polyesters, determined using the suspension method at 25±3°C, range between 1.118 and 1.208 g cm −3. The overall reactivity of diols, based on reduced viscosity values, was found to decrease in the following order: PEBPA>PEPh>PEBPC>PER>PEHq>PEC>PEBPS>PEEG>PEBu-1,4 The thermal stability of polyesters, based on various temperature characteristics, was found to decrease in the following order: PEPh>PER>PEHq>PEEG>PEBPS>PEBPA>PEBPC>PEC

Synthesis and physico-chemical properties of polycyanurates derived from 2-piperidino-4,6-dichloro-s-triazine with various diols

Several polycyanurates were synthesized using stirred interfacial polycondensation of 2-piperidino-4,6-dichloro-s-triazine with various aromatic and aliphatic diols, viz. bisphenol-A (BPA), bisphenol-C (BPC), phenolphthalein (Ph), resorcinol (R), catechol (C), 1,8-dihydroxy anthraquinone (DHA-1,8) and ethylene glycol (EG). The polycyanurates were characterized in terms of solubility, density, viscosity, i.r. spectrum and thermal behaviour. The polycyanurates had reduced viscosities in the range 0.512–0.711 dl/g in chloroform at 25 ± 0.1°. The overall reactivity of diols based on reduced viscosity was found to decrease in the following order: PCBA>PCPh>PCDEG>PCR>PCC>PCDHA−1.8>PCBPC. The thermal stability of polycyanurates based on various temperature characteristics was found to decrease in the following order: PCR>PCDHA−1.8>PCC>PCBPA>PCDEG>PCBPC>PCPh.

Synthesis and properties of homo and copolycyanurates

Three homopolycyanurates were synthesized by stirred interfacial polycondensation of 2-morpholino-4,6-dichloro-s-triazine with each of three aromatic diols viz. bisphenol-A (BPA), bisphenol-C (BPC) and bisphenol-S (BPS). Three copolycyanurates were synthesized using each of the following mixtures of diols: (BPA + PBC), (BPC + BPS) and (BPA + BPS). Polymer yields were in the range 65–83%; products were characterized by density, viscosity measurements, i.r. spectra, solubility tests and thermogravimetric analysis. The polymers had reduced viscosities in the range 0.45–0.84 dl/g in chloroform at 30°. All the polymers were amorphous and soluble in chlorinated solvents. Homopolycyanurate derived from BPC and copolycyanurate derived from BPA and BPC showed greater thermal stability than the others.

Synthesis and Physico-Chemical Properties of Polycyanurates of 2-(N,N-Diphenylhydrazino)4,6-Dichloro-s-Triazine with Various Aromatic Diols

Various polycynaurates were synhesised by stirred interfacial polycondensation of 2-(N.N-diphenynhydrazino)-4,6-dichloro-s-triaziae (DPHDCT) with each of the aromatic diols: bisphenol-A (BPA); bisphenol-C (BPC); bisphenol-S (BPS); phenolphthalein (Ph); catechol; resorcinol; 1,5and 2.7-dihydroxynaphthalene (DHN-1,5 and DHN-2,7) and 1,8-dihydroxyanthraquinone (DHA-1,8). Interfacial polycondensation of DPHDCT with BPA was investigated in detail in order to select optimum reaction conditions. The yield of polycyanurates varies from 6 I% to 79%. The polycyanurates are soluble in chlorinated solvents such as chloroform, dichloroethane. dichloromethane and chlorobenzene. The reduced viscosity for polycyanurates, determined with a 1 g disolution in chloroform at 25 + 3°C was found to be in the range 0.50-0.68 dl g. All the polycyanurates were characterized by IR spectra. The densities of the polycyanurates, determined using the suspension method at 25 3°C, range between 1.196 and 1.330 g cm. The overall reactivity of diols, based on reduced viscosity values, was found to decrease in the following order: PCBPA> PCPh> PCBPC> PCR>PCDHN-2,7 > PCDHN-I,5 > PCC > PCDHA-1.8 > PCBPS. The thermal stability of polycyanurates, derived from various temperature characteristics, was found to decrease in the following order: PCBPA> PCBPS> PCBPC > PCC PCR> PCDHN-2,7 PCDHN-.l 5 > PCDHA-1,8 > PCPh.

Synthesis and properties of homo- and copolycyanurates

Four homopolycyanurates were synthesized by stirred interfacial polycondensation of 2-diethyl-amino-4,6-dichloro-s-triazine with each of three aromatic diols viz. bisphenol-A (BPA), bisphenol-C (BPC), bisphenol-S (BPS) and phenolphathalein (Ph). Four copolycyanurates were synthesized using each of the following mixtures of diols: (BPA + BPC), (BPA + BPS), (BPA + Ph) and (BPC + BPS). The polymers yields were in the range 48–80%. They were characterized by density, viscosity measurements, i.r. spectra, solubility tests and thermogravimetric analysis. The polymers had reduced viscosities in the range of 0.17–0.37 dl/g in chloroform at 30°. All the polymers were amorphous and soluble in chlorinated solvents. Homopolycyanurate derived from BPA and copolycyanurate derived from (BPA + BPC) showed greater thermal stability than the others.