You do raw this way:
DB::connection('mysql1')
->statement(
DB::raw('insert into article_category (name) values (?)'),
array($name)
);
To get the Id after an insert this is a way:
Create a model for your table:
class Post extends Eloquent {}
And create a record on your table selecting a particular connection connection:
$post = Post::on('connectionName')->create($arrayOfvalues);
echo $post->id;