Lecture 12: Organic compounds: Functional groups and the molecules of life FALL 2016 Course lecturer : Jasmin Šutković 6th January 2017

Contents 1. Arenes Alcohols and Ethers Aldehydes and Ketones International University of Sarajevo 1. Arenes Alcohols and Ethers Aldehydes and Ketones Carboxylic acid Molecules of life Proteins Lipids Nucleic acids Carbohydrates

Arenes Most arenes with a single six-membered ring are volatile liquids- AROMATIC HYDROCARBONS (CYCLIC) Compounds containing both aliphatic and aromatic parts. Alkylbenzenes Alkenylbenzenes Alkynylbenzenes Etc….

Volatility ? Volatility is a measure of a substance's vapor pressure and it's tendency to vaporize.

How they are produced?

Aromatic VS. Aliphatic In organic chemistry, compounds composed of carbon and hydrogen are divided into two classes:  aromatic compounds, which contain benzene or similarly aromatic rings of atoms, and  aliphatic compounds  which do not contain those rings.

Alkylbenzenes, nomenclature: Special names

others named as “alkyl benzenes”:

Alcohols Alcohols are characterized by the presence of an -OH group generally in a bent shape, like that of water. Due to the presence of an -OH group, alcohols can hydrogen bond. This leads to higher boiling points compared to their parent alkanes. Alcohols are polar in nature. This is attributed to the difference in electronegativity between the carbon and the oxygen atoms. Are classified as primary, secondary, or tertiary, depending on whether the –OH group is bonded to a primary, secondary, or tertiary carbon

Ethers Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. Good solvents for organic compounds Unreactive because they lack the –OH unit

Reminder

Aldehydes An ALDEHYDE is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center (a carbon double bonded to oxygen) bonded to hydrogen and an R group, which is any generic alkyl or side chain. Contain the carbonyl functional group Prepared by the oxidation of alcohols

Ketones A KETONE  is an organic compound with the structure RC(=O)R', where R and R' can be a variety of carbon-containing substituents. Ketones feature a carbonyl group (C=O) bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology. Examples include many sugars (ketoses) and the industrial solvent acetone.

Carboxylic Acids Compounds that contain the carboxyl functional group are weak= acids. Carboxylic acids are Brønsted-Lowry acids because they are proton (H+) donors. They are the most common type of organic acid. Among the simplest examples are formic acid H-COOH, which occurs in ants, and acetic acid CH3-COOH, which gives vinegar its sour taste. Carboxylic acids are used in the production of polymers, pharmaceuticals, solvents, and food additives.

Examples

Carboxylic Acid Derivatives Esters Esters are chemical compounds consisting of a carbonyl adjacent to an ether linkage. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group, and most commonly from carboxylic acids and alcohols. Esters are responsible for the aroma of many fruits, including apples, durians, pears, bananas, pineapples, and strawberries. Several billion kilograms of polyesters are produced industrially annually.

The Molecules of Life • All the functional groups described are found in the organic molecules that constitute and maintain every living organism on Earth • The most abundant substances found in living systems belong to four major classes: 1. Proteins 2. Carbohydrates 3. Lipids 4. Nucleic acids

Proteins • Proteins are biologically active polymers formed from amino acids linked together by amide bonds; in addition to an amine group and a carboxylic acid group, each amino acid contains a characteristic R group The nature of the R group determines the particular chemical properties of each amino acid !!! • All the amino acids found in proteins are chiral compounds except glycine, which suggests that their interactions with other chiral compounds are selective. • Some proteins are enzymes that catalyze biological reactions

Essential, Nonessential, and Conditional Essential – must be consumed in the diet Nonessential – can be synthesized in the body Conditionally essential – cannot be synthesized due to illness or lack of necessary precursors Premature infants lack sufficient enzymes needed to create arginine

Lipids – Characterized by their insolubility in water – Form a family of compounds that includes fats, waxes, vitamins, and steroids – Fatty acids are the simplest lipids and have a long hydrocarbon chain that ends with a carboxylic acid functional group 1. Saturated fatty acids—the hydrocarbon chains contain only C–C single bonds that stack in a regular array 2. Unsaturated fatty acids—have a single double bond in the hydrocarbon chain (monounsaturated) or more than one double bond (polyunsaturated); double bonds give fatty acid chains a kinked structure, which prevents the molecules from packing tightly

Nucleic Acids • Nucleic acids are the basic structural components of DNA and RNA, the biochemical substances found in the nuclei of cells that transmit the information needed to direct cellular growth and reproduction !! • Structures are derived from nitrogen-containing cyclic compounds called pyrimidines and purines. • When a pyrimidine or purine is linked to a sugar by a bond called a glycosidic bond, a nucleoside is formed; addition of a phosphoric acid group to the sugar produces a nucleotide !

Nucleic Acids • Nucleotides link to form a polymeric chain that consists of alternating sugar and phosphate groups that are the backbone of DNA and RNA!!!! • The function of DNA is to preserve genetic information, and RNA translates the genetic information in DNA and carries that information to cellular sites where proteins are synthesized

DNA AND RNA

Structural Differences Between Carbohydrates, Lipids, and Proteins Figure 6.1

One more lecture to go…. Next Tuesday Lecture 13 Next Friday Seminar presentations