The difference between these two is only in the cooking time; the difference between the syrup and grenadine is the addition of sugar. If you like a tarter flavor, add ½ to 1 teaspoon of lemon juice.
4 cups pomegranate juice
½ cup sugar
Combine in a 4 quart saucepan, and stir over medium heat until the sugar dissolves. Turn heat down to medium-low and cook until reduced to 11/2 cups for syrup (about two hours), or until reduced to 1 cup for molasses (about 1 hour 20 minutes). Cool completely and store in a glass jar in the refrigerator for up to six months.
Use the syrup in beverages, jelly, over fruit or ice cream; use the molasses with vegetables and tofu, in marinades and sauces.