 Streitwieser was one of the pioneers of molecular orbital theory and his book "Molecular Orbital Theory for Organic Chemists" had a lasting impact on the field.He is also well-known for proposing the currently accepted interpretation of the origin of secondary deuterium kinetic isotope effects.Streitwieser developed the technique of using protium/deuterium exchange to measure the acidity of exceedingly weak carbon acids and was a codeveloper of the MSAD acidity scale, named for the first initials of the chemists who developed it.