The acid‐binding properties of long‐chain aliphatic amines

Abstract

is., just before the end-point the indicator is in combination with the anion-active agent and out of direct contact with the added aqueous titrant. To liberate the methylene blue into the aqucous phase a certain minimum concentration OF cation-active substance must be established in the solvent phase by partition from thc aqueous phase which may conceivably require an addition of titrant in considerable excess of stoichiornetric proportions.A consideration of the individual compounds in Table V shows that the slightly high results obtained by titration with bromophenol blue as indicator may in practically every instance be explained by the presence OF some extraneous impurity such as sulphonic acids in the sodium oleyl sulphate and sodium oleate in the sodium oleyl-p-anisidide sulphonate and illustrates the extreme difficulty of preparing amphipathic substances OF absolute purity by ordinary crystallization methods. Conclusions(I) The solubility in organic solvents OF complexes formed between anion-active agents and methylene blue and between cation-active agents and bromophenol blue respectively form the basis of new partition-end-points in the titration OF anionactive with cation-active agents.(2) Procedures are described which enable such titrations to be conducted with greater precision that heretofore.(3) A study OF several purified anion-active agents indicates that virtually stoichiometric results are obtained by the new method on titrating one anion-active agent against another via an intermediate cation-active agent, irrespecure of whether methylene blue or bromophenol blue be used as indicator.(4) The end-point is more readily determined with bromophenol blue than with methylene blue.(5) Thc interpretation of results of titrations of various technical amon-active agents against a highly purified cation-active agent is complicated by the probable presence in these technical products of small proportions of by-products which also titrate with the cation-active agent, e.g., sodium alkyl sulphonates in sodium alkyl sulphates; sodium oleate in sodium oleyl-panisidide sdphonate. It is therefore impossible to state with absolute certainty that, by this method, cation-active agents titrate stoichiometrically with anion-active agents. Using bromophenol blue the relationship is approximately stoichiometric whereas with methylene blue a definite excess of cationactive agent is present at the end-point.(6) A possible explanation is advanced for the higher results obtained with methylene blue.(7) It does not follow that all anion-active or cation-active compounds are suitable for titration by the new method. Thus dodecyltriethylammonium bromide, used as a standard titrant in Table I gave low results for all anion-active compounds tested.(8) The mcthod has proved easy and accurate in the hands of unskilled operators. It is of particular value in following changes in active-agent concentrations, e.g., in studies of absorption by textile fibres, and in the control of continuous processing operations. Imperial Chemical...

Production of Bacteriolytic Enzymes and Degradation of Bacterial Cell Walls During Growth of Agaricus bisporus on Bacillus subtilis

“…Samples for amino acid analysis were hydrolysed in 6 M-HCI at 105 "C for 16 h. Humin was removed by centrifugation, washed with water, and the combined hydrolysate and wash were deacidified by repeated evaporation from aqueous solution in t)acuo over P 2 0 s and NaOH. As this evaporation procedure can cause losses of muramic acid (Ghuysen et al, 1966), hydrolysates for hexosamine analysis (4 M-HCl at 100 "C for 4 h in a N, atmosphere) were neutralized by extraction with N,N-dioctylaminomethane (lo%, v/v in CHC13) (Smith & Page, 1948) after adjustment to about pH 2 with Bio-Rad AG2-X8 resin (HC03-form). DAP was determined by paper chromatography of replicate samples, with a range of standards, on Whatman 3MM paper in solvent system I (butan-1-ol/pyridine/glacial acetic acid/water; 60 :40 : 3 : 30, by vol.)…”

Isolation of Outer Membranes with an Ordered Array of Surface Subunits from Acinetobacter

“…Samples for the paper chromatography of sugars were extracted with a chloroform-methanol (2:1, vol/vol) mixture and hydrolyzed as above, or by treating with 72% (wt/wt) H2SO4 at 22 C for 60 min, followed by dilution to 3% (wt/wt) H2SO4 and autoclaving at 120 C for 60 min (31). In either method, the hydrolysate was neutralized by extraction with N,Ndioctylmethylamine used as a 10% (vol/vol) solution in chloroform (35). Samples were applied to Whatman no.…”

ANTHOCYANINS AND FLAVONOLS OF MIRACLE FRUIT, Synsepalum dulcificum, Schum

“…After cooling the anthocyanidin aglycone was extracted with amyl alcohol. The mineral acid was removed from the aqueous sugar solution by repeated extraction with 10% di-n-octylmethylamine in chloroform (Smith and Page, 1948). These pure extracts of aglycone and sugar were then concentrated and identified with authentic markers by co-chromatography in BAW, Formic and Forestal solvent system in the case of aglycones and BBPW and phenol for sugars.…”