if post id matches these id’s then do this

This looks almost correct. Let’s have a look at is_single():

Works for any post type, except attachments and pages…

So if the given ID isn’t that of a page or attachment post type then you can use the function as so:

if( is_single( 2578 ) ) {
    /* ... */
} else {
    /* ... */
}

Otherwise, if the ID is a page post type you can use is_page()

if( is_page( 2578 ) ) {
    /* ... */
}

Should the ID be that of an attachment page you may use is_attachment()

if( is_attachment( 2578 ) ) {
    /* ... */
}

Finally, if you’re unsure of the post type you could check against the global $post object, assuming it is correct:

global $post;
if( is_object( $post ) && 2578 == $post->ID ) {
    /* ... */
}