How do I change TinyMCE button “i” to create a i tag rather than em? [duplicate]

Here’s a simple function that will replace <em> with <i> on your post/page:

function replace_em_with_i($content) {
$content = str_replace('<em>', '<i>', $content);
$content = str_replace('</em>', '</i>', $content);
return $content;
}

add_filter('the_content', 'replace_em_with_i');

Warning: I have tested the code to check if it works (and it does work), but you might want to do some serious testing before using it…

Using a similar function you can replace <strong> with <b>, and so on.

I hope this helps…