Important Concepts20 1.Electrophilic Reactivity – of the carbonyl carbon in carboxylic acid derivatives: Weakened by good electron-donating substituents Affect accounts for increased basicity: Alkanoyl halides < anhydrides < esters < amides With amides, the large effect causes hindered rotation about the amide bond on the NMR time scale. 2.Nomenclature – of carboxylic acid derivatives: Alkanoyl halides Carboxylic anhydrides Alkyl alkanoates Alkanamides Alkanenitriles

Important Concepts20 3.IR Spectroscopy – of carboxylic acid derivatives: Alkanoyl chlorides – cm -1 Anhydrides – cm -1 and cm -1 Esters – cm -1 Amides – cm -1 4.Reactions of Carboxylic Acid Derivatives Water – (acid or base catalysis) hydrolyze to corresponding carboxylic acid Alcohols – react to form esters Amines – react to form amides Grignard Reagents – react to form ketones Esters may react further to form alcohols. Hydrides – react to form aldehydes, alcohols or amines

Important Concepts20 5.Natural Products Waxes – long-chain esters Oils and Fats – triesters of glycerol Hydrolysis yields soaps Phospholipids – triglycerides containing phosphoric acid ester sub-units. From micelles and lipid bilayers due to polar head and hydrophobic tail 6.Transesterification – used to convert one ester into another

Important Concepts20 7.Nitrides – similar to alkynes; carbon and nitrogen are sp 2 hybridized. IR - ~2250 cm -1 stretch NMR – adjacent protons are deshielded; 13 C absorption for nitrile carbon is at low field (δ ~ ppm) 8.Mass Spectrometry – Magnetic separation of ionized molecules on the basis of molecular weight Ionizing beam may fragment molecules into smaller particles which are separated and recorded as the mass spectrum. Certain elements (Cl, Br) produce recognizable isotopic patterns. The fragmentation patterns can be used to deduce the structure of a molecule.

Important Concepts20 9.High-Resolution Mass Spectrometry – allows molecular formula determination from exact mass values