How would I go about replacing weird quotes?

ex: ‘,’, “, and ”.

Code:
$vCLEANED = str_replace("'", "\'", $vSlashes);
	$vCLEANED = str_replace('"', '\"', $vCLEANED);
	$vCLEANED = str_replace("’", "\'", $vCLEANED);
First two lines work, third one does not.

These are apparently latin extended A and B
http://www.ascii.cl/htmlcodes.htm (bottom)