Function: Preserve HTML entities in WordPress TinyMCE

function my_format_TinyMCE( $in ) {
    // Add some common entities to the default array (copy, reg, trade, service mark, euro, curly quotes, dashes and a few others)
    // The odd entires are the entity *number*, the even entries are the entity *name*. If the entity has no name,
    // use the number, prefixed with a hash (for example, the service mark is "8480,#8480").
    // More entities at: https://dev.w3.org/html5/html-author/charref
    // or search for them here: https://unicodelookup.com

    $in['entities'] = '169,copy,174,reg,8482,trade,8480,#8480,8364,euro,38,amp,60,lt,62,gt,160,nbsp,8220,ldquo,8221,rdquo,8216,lsquo,8217,rsquo,8211,ndash,8212,mdash,232,egrave,233,eacute,246,ouml';
    $in['entity_encoding'] = 'named';
    return $in;

}
add_filter( 'tiny_mce_before_init', 'my_format_TinyMCE' );