71.080.90 - Phenols

Applicable to products having a high o-cresol content and a high m-cresol content. The principle consists in distillation of a tast portion under carefully defined conditions and determination of the mass of residue obtained. The distillation is carried out according to ISO 918. When all the water has distilled over, continue the distillation without intermediate measurements, until either the dry point or the final boiling point is reached.

The test may be carried out on products as received or on a dried sample. The method specified in ISO 2208 shall be applied for drying. The principle of the method consists in cooling the liquid or liquefied test portion and observation of the temperature during crystallization under defined conditions. A simplified crystallization point apparatus is given in the figure. It takes into account the properties of these products.

The method is applicable to products having high cresol contents. The principle consists in distillation of a test portion inder carefully defined conditions. Either determination of the temperatures corresponding to the condensate volumes defined or determination of the volume condensate when the thermometer indicates each of the distillaton temperatures (i.e. plotting temperature as a function of volume or plotting volume as a function of temperature).

This method is applicable to products having a dry residue after evaporation, greater than or equal to 0,005 % (m/m). The principleconsists in evaporation of a test portion in a platinum dish on a boiling water bath and drying of the residue in an oven at (105 +- 2) °C for 1 h. Replaces ISO Recommendation R 1900-1971.

The principle of the method is based on distillation of a test portion in the presence of an appropriate solvent, in a Dean and Stark apparatus. Determination of the volume of condensate collected in the receiver tube, brought to ambient temperature, assuming this liquid to be water. An appropriate solvent is xylene, solvent naphtha or alternatively, toluene. ISO 1897-2 replaces ISO/R 1898-1971.

Simple empirical test of no great precision. The principle consists in shaking a test portion with sodium hydroxide solution under specified conditions and assessment of any insoluble matter present in suspension in the mixture by comparison either with an agreed standard turbidimetric solution or with water. The comparison of the turbidity of the two solutions is carried out by viewing vertically and with the electric lamp equipped with a ligth blue "dayligth" bulb switched on. ISO 1897/5 replaces ISO Recommendation R 1905-1971.

Specifies a method for the comparison of the colour of a test portion against the colour of colorimetric standard colour matching solutions. The colour of cresols present in the test portion is liable to darken on keeping and on exposure to ligth. ISO 1897/7 replaces ISO Recommendation R 1909-1971.

This method is the best available at the present time. It was primarily intended for samples containing 40 % (m/m) or more but has been extended to lower ranges. The principle is based on dehydration of a quantity of the test sample. Formation of a complex between o-cresol and cineole (having a crystallizing point not lower than 1,2 °C) by addition of excess cineole to a test portion of the dehydrated sample. Determination of the crystallizing point of the complex in a crystallizing point apparatus. Calculation of the content from the water content of the test sample and the crystallizing point of the complex. The relation between crystallizing point and o-cresol content of o-cresol/cineole mixtures is given in a table. ISO 1897/8 replaces ISO Recommendation R 1910-1971.

Simple empirical test of no great precision. The principle consists in shaking a test portion with sodium hydroxide solution under specified conditions and assessment of any insoluble matter present in suspension in the mixture by comparison either with an agreed standard turbidimetric solution or with sodium hydroxide solution. The comparison of the turbidity of the two solutions is carried out by viewing vertically and with the electric lamp equipped with a ligth blue dayligth-bulb switched on.

simple test which cannot be used to obtain quantitative results. The principle of the method is based on formation of a brown colour on lead acetate paper due to reaction with any hydrogen sulphide present in a test portion. ISO 1897/6 replaces ISO Recommendation R 1908-1971.

Specifies a volumetric method, after distillation, for determining of neutral oils, and a titrimetric method, after distillation, for determining of pyridine bases. The principle is based on distillation from an aqueous alkaline solution of a test portion. Measurement of the volume of neutral oils collected. Titration of the bases present in the aqueous distillate and in the oils with standard volumetric hydrochloric acid solution using methyl orange and xylene cyanol FF as indicator. An assembled distillation apparatus is shown in a figure.

Gives also the procedure to be used for the determination of water content by the Karl Fischer method. This method is applicable only to liquefied phenol and m-cresol. The determination of density at 20 °C is applicable only to liquefied phenol, m-cresol, cresylic acid and xylenols.

The method is not specific for phenol. It determines tho total amount of material that can be brominated under the conditions of the test. It is applicable to mixtures of about 80 % (V/V) phenol and 20 % (V/V) water. The principle is based on reaction between phenol and bromine from a measured amound of standard bromide/bromate solution. Formation of tribromophenol, follwed by iodometric determination for excess bromine using a standard volumetric solution of sodium thiosulphate.