Hydrophobe chain length

The pify of the leaving group and the hydrophobe chain length can dramatically affect the efficiency of the perhydrolysis reaction. Additionally, the stmcture of the acid portion of the precursor can affect the yield and sensitivity of the reaction to pH. The mono-4-hydroxybenzenesulfonic acid ester of a-decylsuccinic acid (13) undergoes extremely efficient perhydrolysis at much lower pHs than other peracid precursors, eg, decanoyloxybenzene sulfonate (14). This may be because of the neighboring group participation of the adjacent carboxylate as shown in Table 2 (115). 

The composition of AOS and IOS is determined by the choice of the olefin feedstock, by the way the feedstock is sulfonated and by manufacturing conditions. As will be shown later, the structural parameters such as hydrophobe chain length and branching, the ratio of alkene- to hydroxyalkanesulfonate, and (for AOS) the mono disulfonate ratio determine the physicochemical properties of AOS and IOS these in turn determine the performance of AOS and IOS in their end formulations. 

An increase in the amount of hydrophobic modification restricts segmental mobility by an increase of viscosity within the monolayer for the same molecular weight (300,000) and hydrophobe chain length (C g), the polymer monolayer with the higher amount of hydrophobe has a smaller relaxation rate constant (Experiments Numbers 3 and 7). 

Let us first consider the lipid molecular structures required. First is the hydrophobic matching. The length of the hydrophobic chain determines the thickness of the hydrophobic part of the lipid bilayer, this should correspond closely to the dimension of the native membrane. As most biological membranes contain diacylglycerol lipids with hydrophobic chain lengths of 16 18 carbon atoms. Thus, synthetic lipids should possess relatively long hydrocarbon chain length, e.g., 16-18 carbon atoms. 

The regular solution theory may be applied to surface adsorption and micelle formation of mixed nonaethoxylated fatty alcohols with Gaussian distribution In hydrophobic chain length. Such a system can be treated as an Ideal mixture,... 

The rheological properties of all HMHEC polymers are profoundly affected by the hydrophobe molar substitution (MS) and the hydrophobe chain length. For any given hydrophobic moiety, there is a threshold hydrophobe MS below which there are no significant associative interactions. The most common phenomenological evidence for associative behavior is a dramatic increase in the solution viscosity of HMHEC polymers as a function of hydrophobe MS. The solution viscosity of HMHEC polymers continues to increase as a function of hydrophobe MS until the maximum limit of solubility is reached, as which point the HMHEC polymer becomes insoluble in water.33... 

For the sake of brevity, salient aspects of key structure-activity relationships in one homologous series of twelve mono- and bis-acyl homologated spermine analogues (Fig. 12.8) will be first discussed (Miller et al., 2005). We addressed two questions in this study (i) what is the optimal hydrophobic chain length for effective anti-endotoxic activity, (ii) are symmetrical bis-acyl spermines more effective than mono-acyl compounds We found that a carbon number of 14-16 is optimal in mono-acyl spermines (Fig. 12.9) which are, in general, as potent as... 

Equilibration time increases with increasing hydrophobicity (chain length) of the pairing ion. 

With the slow demise of the nonylphenol ethoxylate market due to legislation, the fatty alcohol market has the chance to design alternatives by subtle changes to the hydrophobe chain lengths and alkoxylate levels. The effects must be achieved with biodegradability as... 

Kunieda, H., Uddin, M.H., Horii, M., Furukawa, H. and Harashima, A. (2001) Effect of hydrophilic- and hydrophobic-chain lengths on the phase behavior of A-B-type silicone surfactants in water. /. Phys. Chem. B, 105(23), 5419-26. 

We have examined the stmcture of both ionic and nonionic micelles and some of the factors that affect their size and critical micelle concentration. An increase in hydrophobic chain length causes a decrease in the cmc and increase of size of ionic and nonionic micelles an increase of polyoxyethylene chain length has the opposite effect on these properties in nonionic micelles. About 70-80% of the counterions of an ionic surfactant are bound to the micelle and the nature of the counterion can influence the properties of these micelles. Electrolyte addition to micellar solutions of ionic surfactants reduces the cmc and increases the micellar size, sometimes causing a change of shape from spherical to ellipsoidal. Solutions of some nonionic surfactants become cloudy on heating and separate reversibly into two phases at the cloud point. 

Span 20 is a SORBITAN-MONOLADRAT with a hydrophobic chain length of 11 carbon molecules. Span 80 is a SORBITAN-MONOOLEAT with 17 C-molecules at the hydrophobic chain length. 

In this study, insoluble pol)rmers containing imidazole groups were tested for esterolytic activity with several substrates of differing hydrophobic chain lengths. The substrates used were 3-nitro-4-acyloxybenzoic acid (Sn ). The concentration of substrate used does not allow the formation of substrate micelles, the concentration being below the critical micelle concentration for these esters (28,29). 

The value of Tk increases as the amphiphile hydrophobic chain length increases. The Krafft points of the sodium salts of the classic amphiphiles (alkyl sulfates, sulfonates, and benzenesulfonates) are usually below room temperature. The Krafft point is a function of the counter-ion. Alkaline earth cations give higher Krafft points for sodium laurylsulfate, 7 k = 9°C the values for the calcium, strontium, and barium salts are 50, 64, and 105°C, respectively. 

For POE nonionics, (1) the ratio increases with increase in the number of OE units in the POE chain at constant hydrophobic chain length, the effect becoming less pronounced as the number of EO units increases, and (2) the ratio decreases with increase in the length of the alkyl chain, at constant number of EO units in the POE chain. The first effect is due to the increase in the size of the hydrophilic head... 

For POE nonionics, an increase in the length of the POE chain at constant hydrophobic chain length causes a decrease in r, an increase in the hydrophobic chain length at constant POE chain length causes an increase... 

Lipophilic linkers (Salager, 1998) and hydrophilic linkers (Uchiyama, 2000 Acosta, 2002) are used to increase the value of SP and decrease y. Lipophilic linkers are long-chained alcohols (above C8) and their low oxyethylenation products that increase the surfactant-oil interaction. The most effective ones have hydrophobic chain lengths that are an average of the hydrophobic chain length of the surfactant and the chain length of the alkane oil. Hydrophilic linkers increase the surfactant-water interaction. Examples are mono- and dimethylnaphthalene sulfonates and sodium octanoate... 

Figure 1.4 T(7)-sections through the phase prism of the systems H20-n-octane-C6E2, C8E3, Q0E4 and C12E5 at an oil/(water + oil) volume fraction of = 0.5. In order to determine the respective X-point the phase boundaries are measured only for surfactant mass fractions 7 > 7. An increase of both the hydrophobic chain length / and the size of the hydrophilic head group j shifts the X-point to lower values of 7, i.e. the efficiency increases. Simultaneously the stability range of the bicontinuous one phase microemulsion shrinks dramatically due to the increased extension of the lamellar mesophase (La). (From Ref. [26], reprinted with permission of Elsevier.)...

Figure 1.16 Temperature dependence of the water/oil interfacial tension

P19.32 (a) The increase in temperalure with the hydrophobic chain length is a result of the increased strength... 

Feitkenhauer, H. U. Meyer. Anaerobic digestion of alcohol sulfate (anionic surfactant) rich waste-water—Batch experiments. Part II Influence of the hydrophobic chain length. Bioresour. Technol. 2002b, 82, 123-129. 

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