Titrations with Photoelectric Titrimeter

Nichols, M. L.; Kindt, B. H.

doi:10.1021/ac60042a012

Cited by 25 publications

(10 citation statements)

References 18 publications

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“…Surfactant CMC values are usually influenced by environmental factors and relates to suppliers (Cai et al, 2011). Therefore, simple and fast CMC determination is usually needed, which leads to the development of different CMC determination methods (Kalyanasundaram and Thomas 1977;Karukstis and Gulledge 1998;Nichols and Kindt 2002;Cai et al, 2011;Hussain et al, 2018;Scholz et al, 2018), such as electric conductivity (Scholz et al, 2018), absorbance spectra (Hussain et al, 2018), and fluorescence (Hussain et al, 2018;Scholz et al, 2018) methods. Compared with other methods, the method based on the change in fluorescence intensity has clearly visible and highly sensitive advantages.…”

Section: Cmc Determination Based On the Characteristics Of Strong Aie In Surfactant Dilute Solutions But Non-emission In Surfactant Micelmentioning

confidence: 99%

Optical Characteristics and Applications of AIE Racemic C6-Unsubstituted Tetrahydropyrimidines

Zhu

2021

Front. Chem.

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Racemic C6-unsubstituted tetrahydropyrimidines (THPs) are the products of an efficient five-component reaction that we developed. THPs show strong AIE characteristics, that is, completely no fluorescence in different solvents but strong emission with fluorescence quantum yields (ΦF) up to 100% upon aggregation. However, the ΦF values of their pure enantiomers are lower than 46%. Unlike common AIE compounds with crowded aryl rotors on a π-bond or on an aryl ring, THPs have three completely non-crowded aryl rotors on a non-aromatic chiral central ring (tetrahydropyrimidine). In this mini review, we first discuss the AIE characteristics of THPs and the influences of molecular structures on their molecular packing modes and optical properties, and then present their applications and forecast the development of other racemic AIE compounds.

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Section: Cmc Determination Based On the Characteristics Of Strong Aie In Surfactant Dilute Solutions But Non-emission In Surfactant Micelmentioning

confidence: 99%

Optical Characteristics and Applications of AIE Racemic C6-Unsubstituted Tetrahydropyrimidines

Zhu

2021

Front. Chem.

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“…The surfactant concentrations employed were in the neighborhood of their respective critical micelle concentrations (CMC) as determined by us at an ionic strength equal to that of the experimental system (ca. 1.4 M for the added univalent salt NaCI) by the standard dye solubilization technique (19); these were 1.0 x 10 -3 M for SLS, 5 x 10 -.4 M forCTABand 1.0x 10 -s MforNP9EO. Due to complexities of micellar structure at high surfactant concentrations (e.g., increased viscosities through gel formation), studies of micellar effects on reaction rates have, to date, been almost exclusively limited to surfactant concentrations in the neighborhood of their CMC (12).…”

Section: Procedures For Hydrogen Absorption Studiesmentioning

confidence: 98%

Effect of surfactant micelles on homogeneous catalytic hydrogenation of 2,4‐hexadienoic acid with pentacyanocobaltate(III)‐hydride complex

Nagarajan¹,

Venkataraman²

1981

J Americ Oil Chem Soc

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The influence of anionic (SLS), cationic (CTAB) and nonionic (NP 9E0) surfactant micelles on the homogeneous catalytic selective hydrogenation of 2,4-hexadienoic acid to 2-hexenoic acid in alkaline aqueous solutions of pentacyanocobaltate(llI)-hydride complex was studied at 1 atm pressure and 30 C. The results indicate that, compared to the reactions in the aqueous medium, (a) surfactant micelles present in concentrations in the neighborhood of their critical micelle concentrations (CMC) enhance both the net rate of formation of the pentacyanocobaltate(lll)-hydride complex and its equilibrium concentration by factors of 2 to 5 and 1.1 to 1.5, respectively; (b) the neutral NP 9E0 surfactant micelles enhance the rate of hydrogenation of 2,4-hexadienoic acid by pentacyanocobaltate(llI)hydride complex by a factor of 3, and, (c) the SLS and the CTAB surfactant micelles totally inhibit the hydrogenation of 2,4-hexadienoic acid. Probable mechanistic reasons are also advanced in order to explain the observed activation of the well known pentacyanocobaltate(lll)-hydride complex by surfactant miceiles.

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“…To examine this point, the CMC of the surfactant CPAB was determined in the usual way by determination of "maximum color change rate" when titrating a suitable dyestuff of opposite charge with the surfactant (13). Eosin proved to be most adequate for sharp color change on adding CPAB.…”

Section: Reagent L and C P A B Concentrationsmentioning

confidence: 99%

“…(d) spectrophotometrically (12); (e) by thermometric titration (13)(14)(15); and (f) polarographically (16-18).…”

Section: Literature Citedmentioning

confidence: 99%

Determination of niobium with p-arsonophenylazochromotropic acid and cetylpyridinium bromide

Sanz‐Medel¹,

Rica²,

Pérez-Bustamante³

1980

Anal. Chem.

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Color stabilization and modification of the visible spectrum of the p-arsonophenylazochromotropic acid (L) and Nb(V) binary complex by the addition of surfactants has been studied In the course of a search for improved spectrophotometric methods for niobium. Addition of cationic surfactants resulted in an effective means of color stabilization and brought about a drastic improvement in the intensity of the absorption band maximum (sensitized reactions). The surfactant which gave the most intense absorption band maximum was cetylpyridinium bromide (CPAB). Spectrophotometric measurements indicate the formation of two Nb-L-CPAB ion-association ternary complexes: a complex with the stoichiometry 1:2:4 was formed in approximately 1 M HCI. The other complex had the stoichiometry 1:l:Z and formed in 2-4 M HCI mediums. Both ternary complexes mentioned can be applied to the spectrophotometric determination of niobium and two different analytical methods have been established: the complex formed in a 1.0 M HCI medium provides a method less selective than the complex formed in 2-4 M HCI. The method provided by the former complex is sensitive ( t = 1.87 X lo4 L mol-' cm-I), has a working range of 0.5-5 ppm Nb, and has a relative standard deviation of 0.5 YO. The complex formed in the higher acidity range provides a less sensitive method. The working range is 1-9 ppm and t = 7.40 X lo3 L mol-' cm-I. This latter method is most adequate for a selective spectrophotometric determination of niobium (relative standard deviation being 0.5 YO).Recent research into increasing the absorptiometry sensitivity for trace metal analysis in the visible region has investigated the use of colored metal chelate systems "sensitized" by the presence of a third component (ternary systems).The use of binary metal ion complexes of organic dyestuffs such as Catechol Violet, "sensitized" by the addition of long-chain cationic surfactants such as cetyltrimethylammonium bromide (CTAB) is claimed to be a mode of analytical reaction more generally applicable to the determination of tin ( 1 ) and one of the most sensitive methods available for the absorptiometric determination of' metal ions. Although some attempts have been made to define the mechanisms and associated color changes of such reactions, much more work is needed to elucidate them.Bayley et al. ( I ) concluded from their study that ternary complexes are formed by ion association of the quaternary ammonium group with the metal dyestuff chelate. However. in aqueous solution, this occurs only when micelles are formed. It is thus necessary to form micelles t o obtain the ternary system because the critical micelle concentration (CMC) of the surfactant turned out also to be a critical reaction concentration ( I ) .The work of Ashton et al.(2) on the Sn(1V)-Catechol Violet system in the presence of surfactants of different nature confirmed that the Sn(1V)-Catechol Violet-CTAB system is a ternary ion association system which is probably formed in colloidal solution and dispersed by the excess surfact...

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Titrations with Photoelectric Titrimeter

Cited by 25 publications

References 18 publications

Optical Characteristics and Applications of AIE Racemic C6-Unsubstituted Tetrahydropyrimidines

Optical Characteristics and Applications of AIE Racemic C6-Unsubstituted Tetrahydropyrimidines

Effect of surfactant micelles on homogeneous catalytic hydrogenation of 2,4‐hexadienoic acid with pentacyanocobaltate(III)‐hydride complex

Determination of niobium with p-arsonophenylazochromotropic acid and cetylpyridinium bromide

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