The effect of ion-pairing on the kinetics of the acid hydrolysis of chloropentaamine cobalt(III) ion—I. Effect of sulphate on the aquation of chloropentaamine cobalt(III) ion

Abstract The finding that hexenuronic acid (HexA) groups can be selectively removed from kraft pulps by acid hydrolysis has provided an opportunity to reduce bleaching chemicals. However, there is evidence that the acid hydrolysis is not uniform. In this report, we evaluate the kinetics of acid hydrolysis of HexA in a xylan sample enriched with HexA, a conventional kraft pulp, and three modified kraft pulps: anthraquinone pulp (Kraft-AQ), polysulfide pulp (PS), and polysulfide-anthraquinone pulp (PS-AQ). We found that HexA present in the xylan and conventional kraft pulp behaved similarly toward the acid hydrolysis throughout. On the other hand, HexA present in the Kraft-AQ, PS-AQ and PS pulps was heterogeneous toward acid hydrolysis and the reaction can be separated into two pseudo-first-order kinetic phases, each of which has a different rate constant. The kinetic data provide evidence for the formation of lignin-HexA-xylan complexes during modified kraft pulping processes.

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Kinetics of diluted acid hydrolysis of pentosan in different cellulose materials.

Nippon Nōgeikagaku Kaishi ◽

10.1271/nogeikagaku1924.59.123 ◽

1985 ◽

Vol 59 (2) ◽

pp. 123-128 ◽

Cited By ~ 1

Author(s):

Yoshi KAMIYAMA ◽

Yoshio SAKAI

Keyword(s):

Acid Hydrolysis ◽

Kinetics Of ◽

Hydrolysis Of ◽

Cellulose Materials

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Acid Hydrolysis of Bromazepam Catalyzed by Micelles, Reverse Micelles, and Microemulsions

Journal of Chemistry ◽

10.1155/2015/957950 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10

Author(s):

Ferdousi Begum ◽

M. Yousuf A. Mollah ◽

M. Muhibur Rahman ◽

Md. Abu Bin Hasan Susan

Keyword(s):

Physicochemical Properties ◽

Acid Hydrolysis ◽

Reverse Micelles ◽

Cetyltrimethylammonium Bromide ◽

Order Rate Constant ◽

Excellent Correlation ◽

Initial Decrease ◽

Droplet Sizes ◽

Kinetics Of ◽

Hydrolysis Of

Kinetics of the acid hydrolysis of bromazepam (Bz) has been investigated in micelles, reverse micelles, and microemulcions of cetyltrimethylammonium bromide (CTAB) by spectrophotometric method. The rate of the acid hydrolysis of Bz was found to be enhanced both below and above the critical micelle concentration (CMC) of CTAB in aqueous solution. The pseudo-first-order rate constant (k′) shows an initial decrease for both low and high H+concentrations. With further increase in [CTAB], at low [H+], thek′attains an almost constant value, while, at high [H+], thek′passes through a maximum and then decreases. The kinetic data for catalysis by micelles of CTAB was interpreted with the pseudophase ion exchange (PIE) model. In CTAB/cyclohexane/1-butanol/water microemulsions, as the water to surfactant ratio (wo) increases, the physicochemical properties and droplet sizes of microemulsions significantly change and distinct changes in reaction environment can be marked. The rate of the hydrolysis reaction exhibits excellent correlation with the physicochemical properties and droplet sizes of the microemulsions and reverse micelles of CTAB. At [H+] = 0.001 M, in reverse micelles and microemulsions of CTAB, thek′of the acid hydrolysis of Bz decreases sharply followed by a slight increase with increasingwo.

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