Organic Compounds

Classes of Organic Compounds

• Organic chemistry encompasses hydrocarbons, alkanols, alkanoic acids, aldehydes, ketones, esters, and amides.

Objectives

• Understand the structure of organic substances.
• State the uses of organic substances.

Hydrocarbons

• Organic compounds exclusively containing carbon and hydrogen.
• Can be saturated or unsaturated.

Saturated Hydrocarbons

• Can be cyclic or acyclic.
• Cycloalkanes feature carbon atoms connected in a cyclic arrangement.
• Alkanes have a general formula of CnH2n+2

Unsaturated Hydrocarbons

• Compounds with double or triple C-C bonds.
• Three types exist: Alkenes, Alkynes, and Aromatic hydrocarbons.
• Alkenes have [carbon- carbon double bonds]
• Alkynes have [carbon- carbon triple bonds]
• Aromatic hydrocarbons have delocalized bonding.

Unsaturated Hydrocarbons; Alkenes

• Contain one or more double bonds (C=C), also known as olefins.
• Has the general formula CnH2n
• Carbon-carbon multiple bonds serve as the functional group for unsaturated hydrocarbons.
• Alkenes exhibit trans-cis isomerism.

Examples of Alkenes

• Ethylene triggers further ripening of fruits and vegetables.
• Butadiene presence in coffee (CH2=CHCH=CH2).
• Lycopene and carotenes are isomeric polyenes (C40H56) that provide attractive red, orange, and yellow colors to watermelons, tomatoes, carrots, and other fruits and vegetables.

Naturally Occurring Alkenes

• Pheromones: compounds used by insects to transmit messages.
• Terpenes: aromatic compounds that create scents in various many plants.
• The bioactivity of pheromones hinges on the cis or trans arrangement of the double bond.

Pheromones

• The sex attractant of female silkworm moths is a 16-carbon alkene derivative containing an -OH group.

Terpenes

• Aromatic compounds that give characteristic scents to cannabis, pine, lavender, and fresh orange peels.
• Composed of five-carbon isoprene units linked in different ways.
• Oxygenated, hydrogenated, and dehydrogenated derivatives of terpenes are terpenoids.

Alkynes

• Unsaturated hydrocarbons with at least one carbon-carbon triple bond.
• Each triple bond contains one sigma (δ) bond and two pi (π) bonds.
• The general formula is CnH2n-2

Biologically Active Alkynes

• Efavirenz is an antiritroviral drug.
• Dehydromatricaria is a herbicide that suppresses the growth of other plants.

Benzene

• Arenes are unsaturated cyclic hydrocarbons, with benzene derivatives as examples.
• Benzene has an atomicity of 6, comprised of 6 carbon atoms and 6 hydrogen atoms arranged in a ring.
• General formula for aromatic compounds is C6H6

Aromatic Compounds

• Common aromatic hydrocarbons consist of fused benzene rings sharing a common side.
• These compounds are called polycyclic aromatic hydrocarbons (PAHs).
• Steroids (cholesterol, estrogen, testosterone) contain the phenanthrene structure.

Biologically Important Compounds with Benzene Rings

• Plants synthesize benzene rings from carbon dioxide, water, and inorganic materials.
• Amino acids and vitamins contain benzene rings (e.g., phenylalanine, tyrosine, tryptophan).
• Vitamins K, B2 (riboflavin), and B9 (folic acid).

Functional Groups

• They are specific groups in organic molecules responsible for chemical properties.

Hydrocarbon Derivatives - Alcohols

• Alkanols are alkanes containing a hydroxyl or alcohol functional group (-OH) in place of a hydrogen atom.
• -OH attaches to aliphatic carbon in aliphatic alcohols and to benzene ring in aromatic alcohols.
• General formula: CnH2n+1OH or R-OH.

Commonly Important Alcohols

• Methanol, ethanol, isopropyl alcohol, industrial alcohols like absolute alcohol, denatured alcohol, power alcohol, and alcoholic beverages.

Medical Uses of Alcohol

• As a wound dresser and antiseptic.
• As an antidote for snake bites and methanol poisoning, and as a mild sedative.
• As a preservative and a solvent.
• Some drugs contain alcohol, isopropyl alcohol, and butyl alcohol (e.g., Gabapentin, Temazepam, Benylin).

Carboxylic Acids

• Alkanoic acid is an alkane-containing carboxylic acid functional group (-COOH).
• Alkanoic acids have the general formula: R-COOH.
• Carboxylic acids occur broadly in amino acids and acetic acid.
• They are Brønsted-Lowry acids, serving as proton (H+) donors.

Uses of Carboxylic Acids

• For the production of soft drinks and food products.
• Acetic acid is used in making vinegar.
• Organic acids in the pharmaceutical industry are used in many drugs (e.g., aspirin, phenacetin).
• Beta hydroxyl acid (BHA) makes acne medications.
• Used for manufacturing of soaps.

Aldehydes

• Organic compounds containing the -CHO functional group.
• The general formula is CnH2n+1CHO.
• Have a carbonyl carbon bonded to one H atom, with the remaining being R, cycloalkane, or Ar.

Naturally Occurring Aldehydes

• Provide odors to different substances.
• Examples: Vanillin, Salicylaldehyde, and Cinnamaldehyde.
• Vanillin is from vanilla beans
• Salicylaldehyde is from meadowsweet
• Cinnamaldehyde is from cinnamon)

Uses of Aldehydes

• As reagents for synthesis of other products.
• Formaldehyde preserves biological specimens, is used in embalming, and for disinfection.
• Acetaldehyde is used in the manufacture of vinyl acetate, ethyl acetate, polymers, and drugs.
• Benzaldehyde is used in perfumery, flavoring agents, and the dye industry.
• Cis-retinal, essential for vision, comes from carotene.

Ketones

• Ketones/alkanones are organic compounds with the -CO- group attached to alkyl groups on both sides.
• General formula: CnH2nO (n is greater than 2).
• General representation: R'COR, where R can be the same or different.

Esterification

• Reaction of carboxylic acid and alcohol in the presence of an acid catalyst, creating an ester.
• An ester is a carboxylic acid derivative, where the -OH portion is replaced with an -OR group from an alcohol.

Naming of Esters

• The name contains the name of the alcohol and the acid.
• The chain carbon is from the acid, with the -ate ending.
• The alkyl group from the alcohol appears first.
• The -ate replaces -ioc from the acid.

Examples of Esters

• They're the base for flavours including raspberry, pear, banana, apple pineapple, and orange.

Hydrolysis of Esters

• The hydrolysis of an ester is a reaction where the (-OR) group is replaced by the hydroxyl (-OH) group from water, forming carboxylic acid and alcohol.
• Reaction can be catalyzed with acid or base.

Saponification

• Hydrolysis of esters under basic conditions forms a carboxylate salt.
• Sodium benzoate serves as a preservative.
• It inhibits the growth of bacteria, yeast, and mold.

Amides

• Carboxylic acid derivatives in which the carboxyl -OH group is replaced with an amino group -NH2.

Useful Amides

• Acetamide derivatives acetaminophen and phenacetin serve as pain relievers.

Oxytocin

• An amide that stimulates uterine contractions in childbirth, and lactation after childbirth.

Concise notes on organic compounds. Covers hydrocarbons (saturated & unsaturated), alkanes, alkenes, and alkynes. Good for chemistry students.