Struggling with English has been blamed on Gabriel's failure to make it with Arsenal.
The London Evening Standard says the Gunners have finally begun the task of streamlining their squad after agreeing to sell Gabriel to Valencia for £10million.
Manager Arsene Wenger has repeatedly expressed a need to offload several outfield fringe players deemed surplus to requirements with goalkeeper Wojciech Szczesny the only senior figure to depart so far this summer.
Wenger admitted previously that Gabriel's lack of English was a significant problem following his arrival given he barely spoke a word and has a problem communicating with his team-mates.
Although the 26-year-old underwent regular lessons, it is understood there was only a marginal improvement in his vocabulary.
Valencia released a social media teaser hinting at Gabriel's unveiling last night and the La Liga club are expected to confirm his transfer within the next 48 hours.