Method for fine cleaning of 1-buten flows

Preparation of less than 2000 ppm isobutene related to the 1-butene exhibiting 1-butene containing fractions from technical mixtures of 4C-hydrocarbon (I), which at least contains 1-butene and 2000 wppm to 8 mass% of isobutene, comprises: (i) reacting the isobutene with ethanol in the presence of an acid catalyst to give ethyl tertiary-butylether; (ii) transferring the reactor discharge (II) into a thermal separation, in which 1-butene and ethanol containing fractions are obtained; and (iii) separating the ethanol from the fractions under receipt of 1-butene containing fraction. Preparation of less than 2000 ppm isobutene related to the 1-butene exhibiting 1-butene containing fractions from technical mixtures of 4C-hydrocarbon (I), which at least contains 1-butene and 2000 wppm to 8 mass% of isobutene related to the concentration of 1-butene, comprises: (i) reacting at least a part of the isobutene contained in the technical mixture with ethanol in a reaction zone or a series of at least two sequentially connected reaction zones in the presence of an acid catalyst to give ethyl tertiary-butylether; (ii) transferring the reactor discharge (II) of the last reactor of the series into a thermal separation, in which an ethyl tertiary-butylether exhibiting fraction (III) and a fraction (IV), which exhibits 1-butene and ethanol, are obtained; and (iii) separating the ethanol from the fraction (IV) under receipt of 1-butene containing fraction (V), and optionally (iv) separating 4C-hydrocarbon that are not 1-butene or isobutene, optionally present in the fraction (IV), in at least a further separation step under receipt of 1-butene containing fraction (VI), where the reaction in the first reaction zone (step a) is carried out with at least a three-fold molar excess of ethanol regarding the isobutene contained in the mixture (I). An independent claim is included for a mixture (A) containing upto 98 mass% of 1-butene and less than 2000 wppm of isobutene obtained by the above method.