Артём

$array = [ 'id', 2, 'product', 3 ];
$result = [ ];
while ( $array ) {
    $name = array_shift( $array );
    $value = array_shift( $array );
    $result[ $name ] = $value;
}

var_export( $result );

array (
    'id' => 2,
    'product' => 3,
)

$newArray = [];
$key = null;
foreach ($array as $value) {
  if (is_null($key)) {
    $key = $value;
    continue;
  }
  $newArray[$key] = $value;
  $key = null;
}

var_export($newArray);

$arr = array('id', 2, 'product', 3);
$new = array();

for ($i = 0; $i < count($arr) - 1; $i += 2) {
    $new[$arr[$i]] = $arr[$i + 1];
}

var_dump($new);