How to execute Multiple Loop

I go through first loop to get the first list where the category_name=”Products”.
And the_content I get like this:
Example:
A
B
C
D

I had set a variable name called $product_name = get_the_content() /*$product_category=”A” */
Now I wanna execute a inner loop to get the nested list where the category_name=”$product_category”.
Here is my current code:

<?php query_posts('category_name=Products'); ?>
				<?php while (have_posts()) : the_post(); ?>
                                <li>
					<a>
					<div style="padding:5px;background-color:black;margin-bottom:2px;">
					<div style="display:inline-block;width:100px;vertical-align:middle;">
					<?php if ( has_post_thumbnail() ) { ?>
  					<?php the_post_thumbnail(); ?>
					<?php } ?>
					</div>
					<div style="display:inline-block;height:100%;">
						<a><?php the_title(); ?></a>
					</div>
					</div>
					</a>

					<?php $product_category = get_the_content(); ?>
					<ul>
					<?php query_posts('category_name=$product_category'); ?>
					<?php while (have_posts()) : the_post(); ?>
                                	<li>
						<a><?php the_title(); ?></a>
					</li>
					<?php endwhile; ?>
					</ul>

				</li>
      				<?php endwhile; ?>
				<?wp_reset_query(); ?>

My output just show the first item:
Example:
A

How can I use the multi loop to get the result like:
Example:
A
– product1
– product2
B
– product3
C
– product4
D
– product5
– product6

Sorry that I still new in WordPress