one of the embodiments above the amount of trichloroisocyanuric acid is 1 0 to 2 0 mole equivalent preferably 1 0 to 1 05 mol equivalent in another embodiment in the process according to any one of the embodiments above the amount of tempo is 0 01 to 0 02 mol equivalent in another embodiment in the process according to any one of the embodiments above a solution of tempo in dichloromethane or ethylacetate is slowly added to the solution of 3 oh thf and tcca to allow for safer process and better quality control another aspect of the present invention is a two step process for preparing 3 oxo thf comprising the following steps a conversion of butane 1 2 4 triol iii in the presence of an acid to 3 hydroxy tetrahydrofuran ii and b conversion of 3 hydroxy terahydrofuran according to any of the embodiments of the oxidation process above the cyclization in step a is conducted in the presence of a strong acid such as p toluenesulfonic acid ptsa at a temperature of 150 u00b0 c to 200 u00b0 c preferably 160 u00b0 c to 180 u00b0 c to a 500 ml flask 1 2 4 trihydroxybutane iii 159 g 1 5 mol 1 eq and p toluenesulfonic acid monohydrate 1 5 g 8 72 mmol 0 006 eq were added the solution was heated to 160 180 u00b0 c reaction was monitored by gc the resulting mixture was purified by fractional distillation to give 3 oh tetrahydrofuran.