Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Benzoyl chitosan

Chitosan is insoluble in water, concentrated acids, alkalis, alcohol, and acetone, but dissolves readily in dilute acids. Water-soluble salts of chitosan include the nitrate and the perchlorate. As described on p. 377, formation of chitosan sulfate and the color reaction of chitosan with iodine have been widely used as qualitative tests for the detection of chitin. Nitration of chitosan with a mixture of acetic and nitric acids or with absolute nitric acid enabled both the free ester and its nitrate salt to be isolated. The perchlorate salt of this ester was also prepared, but it was unstable. Chitosan can be W-acetylated to give products similar to chitin except for their greatly reduced chain-length W-formyl-, iV-propionyl-, JV-butyryl-, and iV-benzoyl-chitosan were also prepared. ... [Pg.391]

Uragami et al. (1998) synthesized benzoyl chitosan as a membrane material for the separation of benzene-CYH mixtures via PV. When the benzoyl chitosan membrane was applied for the separation of benzene-CYH mixtures in PV, both the permeation rate and benzene concentration in the permeate increased with increasing benzene concentration in the feed and thus this membrane showed benzene permselectivity. It was reported that the benzene permselectivity was dependent on both the sorption and diffusion selectivity but was significantly governed by the latter. A tentative model for benzene permselectivity was discussed. [Pg.285]

Figure 7 shows that the sequence of the amounts of sorption by benzoyl chitosan gels for various dyes is almost the same as with the octan-oyl chitosan gels. At low degree of substitution of the benzoyl chitosan... [Pg.221]

Fig. 4.4 Increase of p-nitroaniline in a solution containing the trypsin substrate benzoyl-arginine-p-nitroanilide and trypsin at 37°C and phosphate buffer pH 7.6 -o- buffer only, - -0.1% chitosan, -A- 0.025% chitosan-aprotinin,... Fig. 4.4 Increase of p-nitroaniline in a solution containing the trypsin substrate benzoyl-arginine-p-nitroanilide and trypsin at 37°C and phosphate buffer pH 7.6 -o- buffer only, - -0.1% chitosan, -A- 0.025% chitosan-aprotinin,...
Matsugo et al. (1998) reported that, three different water-soluble chitosan derivatives obtained by the acylation of chitosan inhibited thiobarbituric acid reactive substance formation in t-butylhy-droperoxide and benzoyl peroxide induced lipid peroxidations. [Pg.246]

Li reported the first synthesis of calixarene-modified chitosan. The adsorption properties of calixarene-modified chitosan were greatly varied compared with that of chitosan, especially with the adsorption capacity towards Ag and Hg, becanse of the presence of calixarene moiety (Li et al., 2003). Pyravic acid modified chitosan had higher adsorption capacities for Cu + Co than chitosan and salicylalde-hyde modified chitosaa Chitosan benzoyl thiourea derivative has been synthesized and used successfully for the removal of the hazardous Co and Eu radio nuclides from aqueous solutions (Metwally et al., 2009). [Pg.33]

In Table 2, the amounts of the freezable and nonfreezable water are given. For the chitosan gel itself, the higher the amino content, the lower the amounts of the freezable water. The introduction of an octanoyl group (D.S. = 0.3-0.4) leads to the increase of the freezable water. Further increase of the degree of substitution over 0.6 gives a decrease and finally reaches zero at D.S. = 1.0. On the other hand, in the case of dodecanoyl chitosan, the amounts of freezable water decrease linearly with increasing D.S. In the introduction of a benzoyl group, the amounts of the freezable water increases at D.S. = 0.3 and then decreases to the... [Pg.218]

The fact that K2 and S are quite small for chitosan is explained by a compact structure due to the high crystallinity of approximately 40% (density ca. 1.4). 3 jt is worthwhile to note the difference of the effects of benzoyl and octanoyl groups on the sorptivity of dyes. In comparing the values of Ki for Cb-0.5 and Cs-0.6, it is concluded that benzoyl groups cannot interact as firmly as the octanoyl group due to the bulky structure of the phenyl ring. Thus the Ki value of [4] is found to be seven times larger for Cb-0.5 than Cb-0.6. [Pg.224]

Thiolated HA/PEG diacrylate HA/gelatin gradient poly(N-isopropylacrylamide)/HA HA/pendant L-benzoyl-cysteine methacrylated-HA collagen/HA/ chitosan collagen/HA and silk fibroin/HA General... [Pg.159]


See other pages where Benzoyl chitosan is mentioned: [Pg.383]    [Pg.217]    [Pg.222]    [Pg.383]    [Pg.217]    [Pg.222]    [Pg.45]    [Pg.78]    [Pg.76]    [Pg.489]    [Pg.172]    [Pg.546]    [Pg.215]   
See also in sourсe #XX -- [ Pg.217 , Pg.221 , Pg.222 ]




SEARCH



© 2024 chempedia.info