It's not possible to keep place order button out of <form></form>. But you can duplicate the button within the element. This can be done by making a folder woocommerce and inside that checkout. Then got towp-content\plugins\woocommerce\templates\checkout
and copy form-checkout.php
file and paste that into MY_CHILD_THEME\woocommerce\checkout
folder and edit it. (This is to avoid making any changes in woocommerce core file, also it will lost during update)
Modify form-checkout.php
<form name="checkout" method="post" class="checkout" action="<?php echo esc_url( $get_checkout_url ); ?>">
Now add the Button Code as follows
<form name="checkout" method="post" class="checkout"
action="<?php echo esc_url( $get_checkout_url ); ?>">
<div class="form-row place-order">
<noscript>Since your browser does not support JavaScript, or it is disabled,
please ensure you click the &lt;em&gt;Update Totals&lt;/em&gt;
button before placing your order. You may be charged more than the amount
stated above if you fail to do so.&lt;br/&gt;&lt;input type="submit"
class="button alt" name="woocommerce_checkout_update_totals"
value="Update totals" /&gt;</noscript>
<input
type="hidden" id="_wpnonce" name="_wpnonce"
value="c82a4af261"><input type="hidden" name="_wp_http_referer"
value="/woocommerce2/wp-admin/admin-ajax.php" />
<input
type="submit" class="button alt" name="woocommerce_checkout_place_order"
id="place_order" value="Place order" data-value="Place order" />
</div>
<?php if ( sizeof( $checkout->checkout_fields ) > 0 ) : ?>