Critical micelle concentration, hydrophile-lypophile balance, effective chain length and hydrophobicity index of ionic surfactants containing two long-chain alkyl groups

1980 ◽  
Vol 17 (3) ◽  
pp. 119-123
Author(s):  
Israel J. Lin
Keyword(s):  
Critical Micelle Concentration ◽  
Chain Length ◽  
Ionic Surfactants ◽  
Hydrophobicity Index ◽  
Alkyl Groups ◽  
Long Chain

Kinetics of the reaction of the hydrophobic ester 4-nitrophenyl decanoate with long-chain N-alkylimidazoles above and below their critical micelle concentration

1974 ◽  
Vol 27 (10) ◽  
pp. 2149 ◽  
Author(s):  
DG Oakenfull ◽  
DE Fenwick
Keyword(s):  
Critical Micelle Concentration ◽  
Chain Length ◽  
Mole Fraction ◽  
Rate Constants ◽  
Hydrophobic Interactions ◽  
Hydrocarbon Chain ◽  
Hydrocarbon Chain Length ◽  
Hydrocarbon Chains ◽  
Kinetics Of ◽  
Long Chain

The kinetics of the reaction of 4-nitrophenyl decanoate with a series of straight-chain N-alkylimidazoles have been studied at 25� in water and aqueous ethanol. In water, below the critical micelle concentration of the N-alkylimidazole, hydrophobic interaction between the hydrocarbon chains of the reactants caused substantial increases in the reaction rate (up to about 200-fold) compared with the rate of reaction of 4-nitrophenyl acetate with N-methylimidazole. The rate constants, though, differed from those previously reported which were measured with a higher initial concentration of ester. No increase in rate with increasing hydrocarbon chain length could be detected in the presence of a large concentration of ethanol (mole fraction of 0.31) but a rate increase did occur in the presence of a more moderate concentration of ethanol (mole fraction of 0.10), confirming that hydrophobic interactions persist in this mixed solvent. The long-chain ester reacts rapidly with N-alkylimidazole micelles. Association constants (K) for binding the ester to the micelles and rate constants for the reaction of the bound ester (km) were estimated by following the conventional treatment of the kinetics of micelle-catalysed reactions. The value of K was found to increase sharply with increasing hydrocarbon chain length of the micelle but km showed the opposite trend.

The Use of N-alkanes for Estimating Intake and Passage Rate in Horses

1996 ◽  
Vol 1996 ◽  
pp. 98-98
Author(s):  
B M L McLean ◽  
R W Mayes ◽  
F D DeB Hovell
Keyword(s):  
Recent Work ◽  
Chain Length ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Passage Rate ◽  
Forage Crops ◽  
Carbon Chains ◽  
Naturally Occurring ◽  
Chain Lengths ◽  
Long Chain

Alkanes occur naturally in all plants, although forage crops tend to have higher alkane contents than cereals. N-alkanes have odd-numbered carbon chains. They are ideal for use as markers in feed trials, because, they are inert, indigestible and naturally occurring, and can be recovered in animal faeces. Synthetic alkanes (even-numbered carbon chains) are available commercially and can also used as external markers. Dove and Mayes (1991) cite evidence indicating that faecal recovery of alkanes in ruminants increases with increasing carbon-chain length. Thus the alkane “pairs” (e.g. C35 & C36, and C32 & C33) are used in calculating intake and digestibility because they are long chain and adjacent to each other. However, recent work by Cuddeford and Mayes (unpublished) has found that in horses the faecal recovery rates are similar regardless of chain lengths.

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