Since you didn't give any sample data, and your "13 such conditions" leaves a lot to the imagination, I could guess that something like this might give you a starting point for your script. (This is untested, but should be close to a working script.)

Code:

awk '
FNR == NR {
	array[$1] = $2
	next
}
{	for(i = 1; i <= 13; i++)
		if($i in array) break
	if(i <= 13)
		$5 = array[$i]
}
1' file1 file2

with the usual comment that if you want to try this on a Solaris/SunOS system, you need to change awk to /usr/xpg4/bin/awk.