I have a Sony Alpha 100. I also have a Maxxum 4000 AF flash that works great with my Maxxum 7000.

Is there a hot shoe adapter that will allow me to use this perfectly functional flash with the A-100?

There is (or was) an adapter that will let you put your flash on your camera. The Minolta FS-1100. You'll only be able to use the manual flash settings on your Sony, no TTL flash metering.