i found it here: http://digitalmyway.co.uk/2013/05/custom-colour-palettes-in-tinymce-with-wordpress/

and put this in my functions file:

//* —————————————————– CUSTOM TNYMCE text Colour Palette —————————————————–
add_filter(‘tiny_mce_before_init’, ‘my_custom_palette’);
function my_custom_palette( $init ) {
$custom_colours = ‘ “A18759”, $init[‘textcolor_map’] = ‘[‘.$custom_colours.’]’;
return $init;
}

it worked!