Hey everyone, here’s a free SOP for CBN from CBC as a starting material. I can help you do the math to scale it to 5kg if you can’t do it yourself. 
To a stirred solution of CBC (300 mg, 0,954 mmol) in toluene (20 mL), iodine (472 mg, 1,860 mmol) was added. The mixture was refluxed and monitored by TLC (PE-EtOAc 9:1, Rf CBC= 0,27, Rf product= 0,29). After 3 hours, the reaction was quenched by addition of sat. Na2SO3 s.s. and extraction with EtOAc. After drying (Na2SO4) and evaporation, the residue was purified by gravity column chromatography on silica gel with PE-EtOAc 95:5 solution to afford CBN (5) as a brown oil (236 mg, 82%).