Continuing Pent's answer:
1) you could try Synker - however, you'd need to have the sync disabled for that account all the time and then use Synker (e.g. via Tasker) during working hours to "kick" synchronization,
2) if it's only about notification sound, you can pick some custom ringtone from your sd card as a notification sound and while not at work - replace the file with some "silence-only" one,
3) last idea - most time consuming to implement, but probably the best one (assuming you use a separate client for your work email) - use DroidWall and block the exchange app from network when not at work (use LocaleExecute/Secure Settings/Run Shell actions to switch between configurations).
BR,
A.