Abstract: Disclosed is a process for producing .epsilon.-caprolactone which comprises distilling a reaction mixture obtained by oxidation of cyclohexanone to separate impurities, wherein .epsilon.-caprolactone separated in a rectifying column is contacted with an oxygen-containing gas and then distilled. Thereby, a high quality of .epsilon.-caprolactone of in which no coloration occurs during long time preservation can be produced by industrial advantages.

Abstract: A process for the production of a trimellitic acid by oxidizing dialkyl aromatic aldehyde and/or its oxide derivative in a liquid phase, the oxidation being carried out in a lower aliphatic carboxylic acid solvent having a water content of 5 to 70% by weight in the presence of a catalyst containing a heavy metal and bromine or being carried out in a solvent containing a lower aliphatic carboxylic acid in the presence of a bromine-manganese catalyst system containing zirconium and/or cerium, and a process for the production of high-quality trimellitic acid anhydride from the trimellitic acid.

Abstract: A key-in sound-generating circuit comprises a keyboard including dial number keys and function keys, a DTMF signal generator coupled, at the output terminal, with a telephone network, a sound generator for converting, into a sound, the output signal from the DTMF signal generator, and a data processor circuit for executing the key data processing according to the keying operation performed using the keyboard, and supplying a control signal to the DTMF signal generator, the data processor being responsive to the operation of the dial number key, to supply a DTMF signal to the keyboard and the sound generator, and responsive to the operation of the function key, to supply a single-frequency signal to the keyboard and the sound generator.