Browsing by Author "Dr. Harold S. Freeman, Committee Chair"

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    Synthesis and Application of Novel Heterobifunctional Reactive
    (2006-11-20) Zhao, Mengnan; Dr. Harold S. Freeman, Committee Chair
    With the goal of improving the performance of traditional dichlorotriazine reactive dyes, three types of heterobifunctional reactive dyes were synthesized and evaluated in this study. Type 1 dyes were prepared by a reaction of one equivalent of a DCT-based parent dye with two equivalents of cysteamine followed by two equivalents of cyanuric chloride and para-aminobenzenesulfato-ethylsulfone. To make type 2 dyes, cysteine was used instead of cysteamine, and the synthesis of type 3 dyes employed a DCT-based parent dye, and one equivalent of cysteamine, cyanuric chloride, and para-aminobenzenesulfato-ethylsulfone. The visible absorption spectra of the new reactive dyes showed a 7-17 nm increase in λmax compared to parent dichlorotriazine dyes. The structures of new dyes were supported by data from ESI mass spectrometry and results from HPLC analysis indicated that isomeric structures had formed, in which the reaction of cysteamine/cysteine simultaneously occurred at the —NH2 and —SH groups. The application properties of the new dyes on cotton fabric were compared with those of the DCT-based commercial dyes. The results indicated that type 1 and type 3 dyes, which are derived from cysteamine, gave higher exhaustion levels and K⁄S values than the corresponding commercial dyes. Type 2 dyes, which are based on cysteine, did not have a good affinity for cotton. It is believed that the presence of a carboxyl group on the linking moiety distorts the geometry of the dye structure, giving an irregular shape. The results of percent fixation studies showed that type 1 and type 3 dyes can be applied at a lower salt level (40g⁄L) than the commercial dyes and simultaneously give higher fixation and better leveling. Similarly, it was found that the fastness properties of type 1 and type 3 dyes are not adversely affected by modification of the commercial dyes. The above mentioned results suggest that the new dyes can be used to produce standard depths using less dye and salt, giving the potential to reduce color and chloride in reactive dye wastewater.
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    Synthesis, Mutagenicity, and Metabolism of Substituted 4,4'-Aminoakoxyazobenzene dyes
    (2009-05-09) Jeong, Euigyung; Dr. Larry D. Claxton, Committee Member; Dr. Jonathan S. Lindsey, Committee Member; Dr. David Hinks, Committee Co-Chair; Dr. Harold S. Freeman, Committee Chair
    This study is an extension of previous work in our laboratories pertaining to the effects of substituents on the mutagenicity of aminoazobenzene-based dyes. The previous work included a study aimed at exploiting the ability of bulky alkoxy groups to reduce the mutagenic potential of aminoazobenzene dyes, which unexpectedly revealed that 4-((3-(2-hydroxyethoxy-4-amino)phenylazo) N,N-bis(2-hydroxyethyl)aniline (dye 80) was among the more mutagenic dyes in that study, despite having non-mutagenic amines as reductive-cleavage products. The present study was undertaken to unveil the basis for the mutagenic activity of dye 80. To accomplish this goal, a group of substituted 4,4’ –diaminoazobenzene dyes (80, 89-92) was synthesized and their structures were characterized using 1H NMR, TOF-LC-ESI mass spectrometry, and combustion analysis. The purity of each dye was shown by HPLC to be 98-100 %. These new compounds were designed as tests of our hypothesis which stated that the mutagenicity of dye 80 arises from the metabolic cleavage of N-hydroxyethyl groups to give 4-((3-(2-hydroxyethoxy)-4-amino)phenylazo) N-(2-hydroxyethyl)-aniline (dyes 89) and 4-((3-(2-hydroxyethoxy-4-amino)phenylazo)aniline (dye 90) as direct-acting mutagens. 4-((3-(2-hydroxyethoxy-4-amino)phenylazo) N,N-bis-(3-hydroxypropyl)aniline (dye 91) arises from lengthening the N-alkyl groups of dye 80 from 2 to 3 carbons, while 4-((3-(2-hydroxyethoxy-4-amino)phenylazo)-N,N-bis(2-acetoxyethyl)aniline (dye 92) is a capped form of dye 80. Mutagenicity was determined using the standard Ames test in Salmonella strains TA98, TA100, and TA1538 with and without S9 enzyme activation. The results showed that all of the dyes tested were mutagenic at various levels with and without S9 enzyme activation in TA1538. Dye 90 was also mutagenic in TA98 and TA100 with and without S9 enzyme activation, whereas dye 91 was mutagenic only in TA98 with S9 enzyme activation. These results indicated that dye 90 was a direct-acting mutagen. The results also suggested that removing one N-hydroxyethyl group and capping both –OH groups in the parent dye 80 did not affect mutagenicity, whereas removing both N-hydroxyethyl groups produced a strong direct-acting mutagen (dye 90) in all three bacterial strains. Increasing the length of the N-alkyl chain from two to three carbon atoms (dye 91) removed mutagenicity in TA98 without S9 activation. The results from TLC and HPLC analysis of product mixtures from rat liver and hamster liver enzyme S9 treatments of dye 80 and 89 confirmed that the metabolism of dye 80 involved de-hydroxyethylation of the substituted amino group. The analysis of product mixtures from rat liver S9 treatments of dye 92 indicated that the metabolism of dye 92 involved de-acetylation of the O-acetyl groups. Computational studies conducted in this research indicated that the shapes of HOMO and HOMO-1 and their energy differences did not provide a direct correlation between electronic properties and mutagenicity. Similarly, there was no correlation between log P values and mutagenicity.