SynchronizationContext.Current is null when run on different app domains

I have a Web Application running in one machine and the services in another machine (i.e.both are in different App domains). I have a workflow service in my service layer which gets the Synschronization Context from SynchronizationContext.Current. I get the SynchronizationContext.Current always as null. But If I run both my application and service layer in the same machine (i.e. same appdomain) the SynchronizationContext.Current is AspNetSynchronizationContext and it works fine. Can somebody help me to resolve this to run different app domains.