Conventional wisdom is that when added to a sauce, alcohol is evaporated by the heat of cooking.
There will always be some alcohol remaining as long as there is still any kind of moisture in whatever you are cooking. The reason behind this is that the alcohol binds with water and forms an azeotrope (mixture of two or more compounds where the ratio cannot be changed by simple distillation). So as you boil the azeotrope, the ratio of alcohol in the compound stays the same throughout the boiling process. So you will always retain some alcohol, unless you boil off all the liquid.
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