socket.io force disconnect client

I may be doing something wrong here but I can't get my head around this.

The following does not work:

client

$("#disconnectButton").click(function() {
  socket.emit("disconnect");
});

server

socket.on("disconnect", function() {
  console.log("this never gets called");
});

Can't I manually call the disconnect event from the client side? Because the following works:

client

$("#disconnectButton").click(function() {
  socket.emit("whatever");
});

server

socket.on("whatever", function() {
  socket.disconnect();
  console.log("this gets called and disconnects the client");
});