I think you're asking whether you can use a USB-to-serial adapter to enable you to connect a USB webcam to a serial-to-wifi converter. The answer to that is no, unfortunately.
USB defines a hardware interface and a communications protocol. Your webcam driver communicates with the physical webcam by sending image data over USB, and your USB-to-serial adapter sends RS232 data over USB. The video stream and the RS232 stream are not compatible. (And even if your webcam somehow sent data over RS232, USB devices communicate with the operating system, not each other.)
What you are looking for is a bridge -- a way to send USB data over wifi. There are other consumer products which perform this function, e.g. this one or this one.