Introduction to Organic Chemistry PDF

Introduction to organic chemistry: What is the difference between organic, Inorganic and natural substances?? Natural substances: are substances created by allah. Organic substances: are substances have plants or animals source and may be natural or synthetic. Inorganic substances: are substances h...

Introduction to organic chemistry: What is the difference between organic, Inorganic and natural substances?? Natural substances: are substances created by allah. Organic substances: are substances have plants or animals source and may be natural or synthetic. Inorganic substances: are substances have a soil source and also may be natural or synthetic. NOTES:  Organic Chemistry was first interpreted as a branch of modern science in the early 1800s by Jon Jacob Berzelius.  He classified chemical compounds into two groups-organic (have plants or animals origin they may occur naturally and can be isolated from natural resources or synthetically prepared) and inorganic (minerals or non-living matter = have soil source).  Organic chemistry was then needed during world war II.  When German soldiers couldn’t obtain natural rubber from trees due to transportation interruption.  So they prepare synthetic rubber, and the procedure of rubber preparation is an organic synthesis process.  We deal with organic compounds in our daily life, for example sugar, fats, vinegar, perfumes, paints, and medicine are all organic compounds families.  There is a great improvement in the manufacturing of organic compounds and entering it in different industries such as: plastic industry, medicine industry, paints industry, and pesticides. Disadvantages of organic chemistry: 1) Burning organic compounds produce poisonous gases and infusible black solids (burning plastics). 2) Generally organic compounds are very sensitive to heat that some times explosion can occur as in case of alcohols and benzene. 3) Pesticides are organic compounds that can pollute environment (air and water). The difference between organic and inorganic compounds: Inorganic compounds: are chemical compounds that lacks carbon and hydrogen. Ex: iron (Fe), inorganic salts (NaCl, 𝐀𝐥𝟐 𝐂𝐥𝟑 , etc..), limestone 𝐂𝐚𝐂𝐎𝟑. Organic compounds: are chemical compounds contain carbon and hydrogen, so that carbon is the main skeleton or backbone of organic chemistry (ethanol 𝐂𝐇𝟑 𝐂𝐇𝟐 𝐎𝐇, acetic acid 𝐂𝐇𝟑 𝐂𝐎𝐎𝐇, acetone 𝐂𝐇𝟑 𝐂𝐎𝐂𝐇𝟑 etc….) What is the importance of carbon atom?? Carbon is visible in nature in its pure form: graphite and diamond. 𝟔 𝟐 𝟐 𝟐 𝟏𝟐 𝐂 the atomic no = 6 and mass no =12, so carbon electronic configuration is 𝟏𝐬 , 𝟐𝐬 , 𝟐𝐩. So we have four valence electrons, and the importance of carbon atom originates from these valence electrons. 1) Carbon can form 4 single (sigma) covalent bonds. 2) Carbon can form single, double, and triple bonds. 3) Carbon can form cyclic and acyclic compounds. 4) Carbon bond strength with hydrogen is almost equal to the carbon bond strength with any other element. Classification of organic compounds: Organic compounds Hydrocarbons Derivatives of Hydrocarbons Acyclic = Open chain Cyclic hydrocarbons = Alcohols Ethers Aliphatic Carbonyl compounds: hydrocarbons 1. Acids 2. Acyl halides = Acid halides Saturated Unsaturated 3. anhydrides 4. Aldehydes 5. Ketones Alkenes Alkynes 6. Esters Alkanes Amines Amides Alkyl halides Organometallic compounds First derivatives of hydrocarbons: 1) Acids: Functional group: RCOOH  Where R is the alkyl group (no of carbon atoms).  They are generally weak acids compared to inorganic acids. Examples: 1) Formic acid (HCOOH) is found in bees and ants. 2) Acetic acid (𝐂𝐇𝟑 𝐂𝐎𝐎𝐇) is found in vinegar. 3) Lactic acid is found in milk. 4) Citric acid is found in lemon, orange and guava. 5) Oxalic acid is found in tomatoes. 6) Malic acid is found in apples. Uses: 1) Food industry. 2) Polymer. 3) Soap. 4) Cleaners. 2) Alcohols: Functional group: ROH  Where R is the alkyl group (no of carbon atoms).  They are generally colorless liquids.  Have distinct smell.  They are volatile. Examples: Ethyl alcohol (𝐂𝐇𝟑 𝐂𝐇𝟐 𝐎𝐇) Ethanol: Methyl alcohol (𝐂𝐇𝟑 𝐎𝐇) Methanol: ‫السبرتو األبيض‬ ‫السبرتو األحمر‬ 1) Produced naturally from fermentation of 1) Produced from burning wood. apples and sugarcane. 2) Not allowed to be used for drinking or in 2) Is used in the manufacture of alcoholic medicine fields. drinks and can be used in different medicine fields. Uses: 1) Detergents. 3) Perfumes. 2) Solvents. 4) Paints. 5) Synthesis of organic compounds. 3) Aldehydes: Functional group: RCHO  Where R is the alkyl group (no of carbon atoms).  High molecular weight aldehydes have pleasant odor and pleasant flavor. Examples: 1) Vanillin aldehyde has vanillia flavor (it is the primary component of the extract of the vanilla bean). 2) Benzaldehyde has flavor of almonds (it is the primary component of bitter almond oil). 3) Cinnamaldehyde gives flavor of cinnamon (found in park of cinnamon trees).  Formaldehyde is used as a disinfectant in hospitals, and used in manufacture of paper, glue and plastic. Uses: 1) Food industry. 2) Disinfectants 3) Perfumes. 4) Plastics. 4) Ketones: Functional group: RCOR or RCOR’  Where R and R’ are the alkyl groups (no of carbon atoms). Examples: Acetone (𝐂𝐇𝟑 𝐂𝐎𝐂𝐇𝟑 ) is the most famous ketone, it is used as a solvent. Uses: 1) Plastic. 2) Solvents. 3) Paints. 5) Esters: Functional group: RCOOR or RCOOR’  Where R and R’ are the alkyl groups (no of carbon atoms). Esters generally have fruity flavor. Uses: 1) Food industry. 2) perfumes. 3) Soap industry. 6) Alkyl halides: Functional group: R-X  Where R is the alkyl group (no of carbon atoms) and X are the halogens (Cl, Br, I, F). Uses: 1) Refrigerants. 2) Plastic 3) Solvents (𝐂𝐇𝐂𝐥𝟑 = chloroform an excellent solvent). 4) Used in fire extinguishers (𝐂𝐂𝐥𝟒 = carbon tetrachloride). Second acyclic hydrocarbons: Naming of hydrocarbons (IUPAC) (naming linear simple chains ONLY): Every name consist of prefix and suffix. The prefix of the names is denoted by the number of carbon atoms in the hydrocarbon chain. The suffix is according to the last parts of the words alkane, alkene and alkynes.  Alkanes Alkenes Alkynes Molecular formula: Molecular formula: Molecular formula: 𝐂𝐧 𝐇𝟐𝐧+𝟐 𝐂𝐧 𝐇𝟐𝐧 𝐂𝐧 𝐇𝟐𝐧−𝟐 No double bonds or triple bonds Double bond Triple bond (saturated with hydrogens) Examples: Examples: Examples: 𝐂𝐇𝟒 Methane 𝐂𝟐 𝐇𝟒 Ethene 𝐂𝟐 𝐇𝟐 Ethyne 𝐂𝟐 𝐇𝟔 Ethane 𝐂𝟑 𝐇𝟔 propene 𝐂𝟑 𝐇𝟒 propyne 𝐂𝟑 𝐇𝟖 Propane 𝐂𝟒 𝐇𝟖 𝐁𝐮𝐭𝐞𝐧𝐞 𝐂𝟒 𝐇𝟔 𝐁𝐮𝐭𝐲𝐧𝐞 Third cyclic hydrocarbons: Cyclic Heterocyclic compounds Homocyclic compounds are compounds containing carbon and other elements Aromatic like S,N,O etc Aliphatic = Alicyclic = cycloaliphatic Benzenoid = Saturated Unsaturated Have a Furan Pyridine benzene ring Cyclo Cyclo NonBenzenoid = Cyclo alkenes alkynes Does not have a alkanes Benzene Naphthalene benzene ring Cyclopropane Cyclopropyne Cyclopropene Phenol (used as a disinfectant) Toluene (used in TNT) Azulene What are the conditions for a compound to be aromatic? 1) Aromatic compounds must be cyclic. 2) Aromatic compounds must have alternating double single bonds (completely conjugated). 3) Aromatic compounds must obey huckel’s rule, so they must contain 𝟒𝒏 + 𝟐𝝅 electrons. 4) Aromatic compounds must be planar. Most famous example is the benzene ring: Other examples: Cyclobutadiene Cyclobutene Cyclohexene antiaromatic Not aromatic Not aromatic Cyclooctatetraene Not aromatic Cyclohexadiene Aromatic Not aromatic Bond Cleavage (Bond breaking): 1) Hemolytic Cleavage: (homogenous).. Light + A B 𝐀 𝐁 Both A and B have the same (equal) electronegativity (is the measure of the The bond is broken hemolytically. So each of ability of the atom to attract the A and B will take its shared electron in the electrons of the covalent bond to it self.) covalent bond giving free radicals. 2) Heterolytic Cleavage: (inhomogeneous) + − + 𝐀 𝐁 Anion A B Nucleophile A and B have the different Cation electronegativity. Electrophile B is more electronegative than A, So heterolytic cleavage take place to the bond and B will attract the electrons of the bond towards it. Reactive Intermediates: 1) They are highly energetic species. 2) They have short life time (unstable). 3) They appear in the middle of the reaction. What are the types of reactive intermediates?? 1) Free radicals (carbon free radicals):. Light 𝐂𝐇𝟑 𝐂𝐇𝟑 𝟐𝐂𝐇𝟑 The two carbon atoms have the same electronegativity so hemolytic cleavage take place producing carbon free radicals = carbon radical. The carbon radical has the following properties: 1) Neutral (as each carbon atom take its shared electron in the covalent bond). 2) Very reactive (unstable). 3) Has 7 valence electrons so it want to complete the octet to be stable. 2) Carbocation's: + − 𝐂𝐇𝟑 Cl 𝐂𝐇𝟑 + 𝐂𝐥 The Cl has more electronegativity than the carbon, so heterolytic cleavage take place and Cl will attract the electrons of the covalent bond to it self giving anion (acquire a negative charge) and the carbon will be the cation (carbocation) (acquire a positive charge). The carbocation has the following properties: 1) Positively charged (electrophile). 2) Very reactive (unstable). 3) Has 6 valence electrons so it want to complete the octet to be stable. 3) Carbanaion's: − + 𝐂𝐇𝟑 H 𝐂𝐇𝟑 + 𝐇 The carbon has more electronegativity than the hydrogen, so heterolytic cleavage take place and carbon will attract the electrons of the covalent bond to it self giving anion (carbanion) (acquire a negative charge) and the hydrogen will be the cation (acquire a positive charge). The carbanion has the following properties: 1) Negatively charged as the two electrons are attracted by the carbon (nucleophille). 2) Very reactive (unstable). 3) Has 8 valence electrons. Why carbanions are unstable as they have 8 valence electrons?? The two electrons attracted by the carbon atom are not actually in a bond they are free electrons, so there is great repulsion force between these free electrons and the electrons bonded to hydrogen atoms, and this repulsion force is responsible for the instability of carbanions. Another reaction in which carbanion is formed: The hydroxide anion represent the base present in the medium. Here the base (hydroxide anion) abstract the hydrogen from the methane giving water, leaving the bonded electrons to the carbon as it is more electronegative than the hydrogen, so carbanion is formed. 4) Carbenes: In step 1: the hydroxide anion abstract the hydrogen atom from the chloroform giving water, and leaving the bonded electrons to the carbon atom as it has higher electronegativity than the hydrogen atom. In step 2: the chlorine has higher electronegativity than the carbon so it will attract the electrons of the bond to it self..‫الهيدروجن عوض الكربون باإللكترونات التي فقضت بسبب الكربون‬ The di chloro carbine has the following properties: It has 6 valence electrons so it is unstable, it want to complete the octet. Most famous organic reactions: 1) Substitution reactions: ‫تفاعالت األحالل‬ A reaction in which a sigma bond is broken and another sigma bond is formed at the same carbon atom. 2) Elimination reactions: ‫تفاعالت النزع‬ A reaction in which two sigma bonds are broken and a bi bond is formed between adjacent atoms. 3) addition reactions: ‫تفاعالت األضافة‬ A reaction in which a bi bond is broken and two sigma bonds are formed. Addition reactions are opposite to elimination reactions.