Chem 102 1st Edition Lecture 15 Outline of Last Lecture I. Chapter 15: Lessons 4.9-4.11 : Preparation of Aldehydes and Ketones, Oxidation and Reduction of Aldehydes and Ketones, Reaction of Aldehydes and Ketones with AlcoholsOutline of Current Lecture II. 5.1 - Structure of Carboxylic Acids and Their DerivativesIII. 5.2 - IUPAC Nomenclature for Carboxylic AcidsIV. 5.3 - Common Names for Carboxylic AcidsV. 5.4 - Polyfunctional Carboxylic AcidsCurrent Lecture5.1 Structure of Carboxylic Acids and Their Derivatives• Carboxylic acid: An organic compound with carboxyl functional group • Carboxyl group: A carbonyl group (C=O) with a hydroxyl group (—OH) bonded to the carbonyl carbon atom • A general structural representation for a carboxyl group is shown below • Carboxylic acid derivative: An organic compound that can be synthesized from or converted into a carboxylic acid. • Four important carboxylic acid derivatives: – Esters – Acid chlorides – Acid anhydrides – Amides Acyl Groups and acyl compounds • The general structure of carboxylic acids and carboxylic acid derivatives can be represented as; • Carboxylic acids and carboxylic acid derivatives all have acyl groups and are therefore called acyl compounds. Aldehydes and Ketones have acyl groups but are not classified as acyl compounds because their carbonylcarbons are bonded to the less electronegative H or C atoms. Instead, they are classified as carbonyl compounds5.2 IUPAC Nomenclature for Carboxylic AcidsIUPAC Rules for Naming Monocarboxylic Acids Rule 1: Select the longest carbon chain that includes the carbon atom of the carboxyl group as the parent chain. Rule 2: Name the parent chain by changing the “-e” ending of the corresponding alkane to “-oic” acid. Rule 3: Number the parent chain by assigning the #1 to the carboxyl carbon atom, but omit this number from the name. Rule 4: Determine the identity and location of any substituents in the usual manner, and append this information to the front of the parent chain name. Rule 5: If the carbonyl group is bonded to a carbon atom in the ring, name the ring and add the words carboxylic acid. The carbon bearing the carboxyl group is always carbon 1. Locate any other ring substituents in the usual manner. Dicarboxylic Acids • Dicarboxylic Acids: Carboxylic acid that contains two carboxyl groups. • Saturated acids of this type are named by appending the suffix “-dioic” acid to the corresponding alkane name. • Unsaturated acids are named in similar manner Aromatic Carboxylic Acids • The simplest aromatic carboxylic acid is called benzoic acid. • Other simple aromatic acids are named as derivatives of benzoic acid.5.3 Common Names for Carboxylic Acids• Common names are usually derived from some Latin or Greek word that is related to a source for the acid • Name of a monocarboxylic acid is formed by taking the Latin or Greek root name for the specific number of carbon atoms and appending the suffix “–ic” acid. − The positions of substituents are denoted by Greek alphabet rather than numbers with reference to the carbonyl carbon (C1), e.g., C2 is alpha (a), C3 is beta (b), C4 is gamma (g), and C5is delta (d). Common Acids • Acetic Acid: CH3COOH – Vinegar is 4%-8% (v/v) acetic acid solution – Colorless liquid with sharp odor • Oxalic acid: HOOC-COOH - found in spinach and cabbage - Harmful at high concentrations - Used to remove rust, bleach straw, and leather and ink stains 5.4 Polyfunctional Carboxylic Acids• Polyfunctional carboxylic acids (PCAs) contain at least one or more functional groups other than carboxyl group • PCAs are commonly found in living organisms and play an important role in human body – Occur in many fruits – Used in over the counter skin care products and prescription drugs • Common types of PCAs: – Unsaturated acids – Hydroxy acids – Keto acidsUnsaturated Acids • Contain at least one carbon-carbon double bond (C=C): • Two types of monounsaturated carboxylic acids: – Trans - unsaturated carboxylic acids – Cis – unsaturated carboxylic acids Hydroxy Acids • Contain at least one hydroxyl group and are naturally present in many foods • Examples: – Glycolic acid: present in juice from sugar cane and sugar beets – Lactic acid: Present sour milk, sauerkraut, and dill pickles – Malic acid and tartaric acid occur naturally in fruits Keto Acids • Contain a carbonyl (C=O) group within a carbon chain. • Example: – Pyruvic acid - simplest keto acid with odor resembling that of vinegar (acetic acid) and it is also ametabolic