Is it permissible, out of necessity, to disregard the timings of salaried work, such as for a person to pray six rak'ahs before Dhuhr and then leave for work upon completing them?

Time-bound supererogatory prayers must be performed within their specified times. Performing the two rak'ahs before Dhuhr does not suffice for performing them after Dhuhr. It is possible to pray the two rak'ahs after Dhuhr at work or at home, if feasible, before the time for Asr prayer begins, because the Prophet, peace and blessings be upon him, encouraged performing supererogatory prayers in homes, saying: "O people, pray in your homes, for the best prayer is a person's prayer in his home, except for the obligatory prayers." And he said: "The superiority of a man's prayer in his home over his prayer where people see him is like the superiority of an obligatory prayer over a supererogatory one."