use strict;

my $string = "this is my sting with \ and /slashes. put substing in quotes"; 
my $substring = "with \ and /slashes"; 
print $string;

$string =~ s/\Q$substring\E/\"$substring\"/gi;

OUTPUT:
this is my sting with  and /slashes. put substing in quotes

##</code><code>##

use strict;

my $string = 'this is my sting with \ and /slashes. put substing in quotes'; 
my $substring = 'with \ and /slashes'; 
print $string;

$string =~ s/\Q$substring\E/\"$substring\"/gi;

OUTPUT:
this is my sting with \ and /slashes. put substing in quotes