<?php
function redirect_after_comment ()
{
    if("/blog/one/" == $_SERVER["REQUEST_URI") {
        wp_redirect('web.com/thank/');
    } elseif("/blog/two/" == $_SERVER["REQUEST_URI") {
        wp_redirect('web.com/thank2/');
    } elseif("/blog/three/" == $_SERVER["REQUEST_URI") {
        wp_redirect('web.com/thank3/');
    } elseif("/blog/four/" == $_SERVER["REQUEST_URI") {
        wp_redirect('web.com/thank4/');
    }
}