CHM 102: A Brief History of Organic Chemistry PDF

Okay, here's the conversion of the provided text and equations from the images into a structured Markdown format. I've done my best to preserve the information and formatting. ## CHM 102 General Chemistry II ### A Brief History of Organic Chemistry Organic Chemistry is the study of compounds that...

Okay, here's the conversion of the provided text and equations from the images into a structured Markdown format. I've done my best to preserve the information and formatting. ## CHM 102 General Chemistry II ### A Brief History of Organic Chemistry Organic Chemistry is the study of compounds that contain carbon (tetrahedral). It is one of the major branches of Chemistry. The history of organic chemistry can be traced back to ancient times when medicine men extracted chemicals from plants and animals to treat members of their tribes. Eg Willow bark which contain acetylsalicylic acid (an active agent in Pain Killers). Organic Chemistry was first defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius. He classified chemical compounds into two main groups: ORGANIC, if they originated in living or once-diving matter and INORGANIC if they came from "mineral" or non-living matter. **NB** Berzelius believed in Vitalism - the idea that Organic compounds could only originate from living organisms through the action of some vital force. It was a student of Berzelius who made a discovery that would result in the abandonment of Vitalism as a scientific theory. In 1828, frederich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic component) **Procedures** Wöhler mixed silver cyanate and ammonium chloride to produce solid silver chloride and aqueous ammonium cyanate. $AgOCN_{(s)} + NH_4Cl_{(aq)} \rightarrow AgCl_{(s)} + NH_4OCN_{(aq)}$ He then separated the mixture by si trahon and ** tried to purify the aqueous ammonium cyanate loy evaporating the water. to lis surprise, the solid left over after the evaporation of the water was not $NH_4OCN$ lout urea! Wöhler's observation marked the frist time an organic compound had been synthesized from in organic source. $NH_4OCN (g) \rightarrow (NH_2)_2CO (s)$ Inorganic Organic (urea) * khöhler's discovery was a turning pond in Science History fur two reasons, * Undermining the idea Vitalism * Discovery of Isomerism (Father of cromerism - Fredrich klöhler). Thes led to fanter theories. By 1860's chemists like Kékulé were proposing theone's on the relationship between a compounds chemical formula and the physical distribution of its atoms, (Father of resonance). Boy 1900's chemists were trying to determine the nature f Chemical Bonding by develyong models for electron distri-bukion. The number of organic componols increased rapidly. During the 20th century, organic chemistry toranched into sub-disciplines. such as polymer chemistry, pharmacology, bio-engmeemy, petro-chemistry and others. To day over 98% of all known compounds are organic. There ane Three generally accepted sources of organic Componde; (Carbonized organic matter, living organisun and invention/human ingenuity.) ### Nomenclature and Classes of Organic Compounds There are over six (6) million known organic compounds. Nomenclature is therefore very important. Basic Guidelines in Naming Simple Organic Comple 1. Find the Longest carbon chain in the molecule. This will give the base of the name **Table 1:** No of Catoms Name | | | | :-- | :---------- | | 1 | Meth- | | 2 | Eth- | | 3 | Prop- | | 4 | But- | | 5 | Pent- | | 6 | Hex- | | 7 | Hep- | | 8 | Non- | | 10| Dec- | 2. Determine the Principal Functional Group and its Position on the Longest Carbon Chain. **Table 2.** Principal Functional Group Formular Ending of Name | | | | | :------------ | :------- | :---- | | Alkane | C-C | -ane | | Alkene | C=C | -ene | | Alkyne | $C \equiv C$ | -Yne | | Alkohol | -OH | -anol | | * Aldehyde | $-C=O$ | -anal | | * Ketone | $H \quad$ | | | | -C=O | -anone| | * Carboxylic acid| $-C=O$ | -anoic acid| | | $OH \quad$| | Position is indicated, where recessory, bay numbering the carbons in the main cham. Position need not be indicated in alkanes as they have no functional group, and aldehydes, and acids, as they are terminal funchinal groups. **NB!** Position numbers are flanked bay dassh designs signs. Multiple positions for a guien fun chìmal group are separated by commal and indicated by the prefixes. di, tri, tetra, penta, hexa, hepta, octa, nona anel deca. 3. Ancillhang fun chinal groups are given in alphabetical order, with their position at the begining of the name. Ancilliang Functional Corp | Formula | Prefix |---|---|---| Methyl | -CH3 | methyl Ethyl |-Catts | Ethyl Propyl |-C3H7 | Propyl Butyl |-C4H9 | Butyl Penty! |-6H13 | Pentyl Hexyl |-4H13 | Hexyl Hepty! |-C7 H15 | Heptyl Ocky! |-817 |Octyl Nony! |-GHra |Nonyl Decyl |-CIOH21 |Decyl Fluorine | -F |Fluoro Chloro |- CL | Chloro Bromme |-Br |Bromo Iodine -I | lodo Amine -NH2 | Amino Hydroxy -OH | Hychroxyl Cyanide -CN | Cyano Benzyl -$C_6H_5CH_2$ | Benzyl Phenyl -$C_6H_5$ | Phenyl The name of any grien compound containing a chain of carbon atoms consists of three parfs: * The Root of the name which appear in the middle (this is further divided into the carbon chain designatin and the infix * The prefix which appears at the start; anel * The suffix which appears at the end. The Root This is divided into two sections - the chain designa-tion and the infix. * The Chain designation fells us the number of Carbon atoms containted in the longest continuous carbon chain in the molecule. This is based in Table 1 above * The infire tells us the nature of the Carbon bonds This is based on the system shown in Table 3 below. **Table 3:** | Infix | Nature of Carbon-Carbon Bands | | :----- | :------------------------------- | | -an- | only single buongle | | -en- | One or more double bunds | | -on- | one or more tripple bonels | | -yl- | attached group (not part of the main carbon chain).| 2. The Suffixe This tells the class of campond to which the substance belongs. It is derived from the most important functional group in the molecule, (Essentially, the more sxygen and the less hydrogen, the more important the functional group. | Suffix | Class of Compond | | :--------- | :----------------- | | -oic acid | alkanoic acid R-z-O-H| | -oate | ester R-2-O-R | | -al | alkanal $H - \overset{O}{C} - C - C$ | | -one | alkanone $C - \overset{O}{C} - C$ | | -ol | alkahol R-C-OH | | -e | lychrocarbone $C - C - C$ | 3. The Prefix This tells the other atoms and groups of atoms attached to the main carbon chain. It may be Single species as halogen atoms, carbon chains smaller than the main Carbon chain or even rings of carbon atoms. The three parts of the name are linked together as shown: PREFIX\_ROOT-SUFFIX Prefix - Root (Caubonchamishufix) - Suffixe Example: 2,4-dimethyl pestane $CH_3$ $CH_3-CH-CH_2-CH-CH_3$ ( 2,4, dimethylpentane) $CH_3$ To name this comparmed, la. First Con't the longest continuos chain- * Pent- 1b. As the molecule contains only single bonds to the Carbon and hydrogen atoms the infix is an- Therefore the root name is pentan- 2. Next add the suffix. As this molecule is blychocarbon the suffix is just-e. Therefore the Boot plus suffix is pentane Finally, we must attack list the attached groups as prefixes. In this case there are two groups attached to the main chain. They are both single carbon groups. kthen naming carbon chaine that care attached to the main carbon chain, the same naming anven-tuss ere used as in determining the root of the name for Canben designation, but the infiss - yol is employed to distin-guish attached chams from the mam carbon carbon chầm. NPR. Therefore the attached groups ane referred to as mettyl groups. 3. If there is guy ambiguity as to the position of the attached groups they must be numberad. he numbering and listing system has the following miles * the longest continuous Carbon chain is mumbered such that the most important functional group is given the lowest number. * the attached groups are listed alphabetically. * the member of the carbon atom from the main chain to which the group is attached is placed in front of the name of the group and a hyphen placed between them. * If there is more than one type of group attached them the pre-prefixes listed below are used to state how many of each attached group is present. | Pre- Prefix | Number of Attached Groups | | :---------- | :------------------------- | | di- | two | | tri- | three | | tera- | fair | | Penta- | five | | hexa- | Six | This implies that the name of the compound is 2,4-dimethylpentame. Description of image: Image has 2 chemical formulas * $CH_3$ $CH_3-CH-CH_2-CH_2-CH_3 \quad 3-mellyl-1-butanol$ * chemical structure of 3-ethylcyclohexanone, with a carbonyl group shown on the ring Alkane: formula $C_nH_{2n+2}$ Alkene: formula $C_nH_{2n}$ See Image for all the compounds Shorthand Notation for Drawing Organic Structures. Organic molecules often appear to have large complex Structures , butt is reality they consists of ( $CH_3$ ), ( $CH_2$ ) and CH- groups plus a for others ). Rather than drawing bulky structures showing all the cetams, chemists wee a shirtand notation to allour these structures to be drawn very rapidly and simply. Individual carbon atoms are represented by inflere-torns in a line and the hydrogen atoms ane left out completely. Double and Tripple bonds are drawn in as required. kej. $CH_3CH_2CH_3$ is represented as > NET The start , end amel each point of inflection represe nt a c-atom. EO $CH_3CH_2CH=CH_3$ is, lass work: Draw skeletal strictines for: 1. Pentane 2. 2-mettylpropane 3. 3-methylheptane 4. 2,2,3-trimethyloctane 5. 3,5-dimettylheptane 1-ethyl-3-propyleyclohexanie. inaite the correctnct comert systematic names for each of the Structures See Image for chemical formulas HOMOLOGOUS SERIES Homologous series is a series of Compounds is which cach successive compound differs from the previous one by a -$CH_2$ init -$CH_2$- HOMOLOCIOUS SERIES IN HYDROCARBONS Hydrocarbons are a family of compounds containing only hydrogen and Carbon. There are two main Classes: Aliphatics and Aromatics. Within the Aliphatics, there are both saturated and unsaturated bychrocarbons Saturated Hychrocar bons (Alkanes) The Homologous dermes of Saturated Hychrocarbons has the general formula $C_nH_{2n+2}$ (where in is an integer) kg where n=1 $CH_4$ , where n=2, $C_2H_6$ and so on. Unsaturated Hydrocarbons (Alkenes & Alkynes) Alkenes: The Homologous series of alkenes (componds with a single double bond) have the general formulber $C_nH_{2n}$ (n is an interger greater than 1). eg ethene $C_2H_4$ propene $C_3H_6$ and so on See image for compound. $C_4H_{2x4-2}=C_4H_6$ Alkynes: The Homologous series of alkynes (compounds inth a single triple land) have the general formular $C_nH_{2n-2}$ (where n is an integer greater than 1). Eg Cath, $C_3H_4$, $C_4H_6$ and so on. 1. the General formular for Cyclo alkanes is Gatten. 2. Cycloalkenes is Gatten-2 and cycloalkytnes is the f The aromation compounds contain benzene ring(6) eg. Benzene, $C_6H_6, \quad$they are called aromatics because of the sweet smell that benzene confers to to the berzene containing compounds. Before gong furker, it is important to understand why we can have single, double and triple Cambon-Carbon bonds. That brings us to the what is known as Hybridization This is the process of designing models to give explanation, for the single, double and triple bounds found in organic compounds Hybridization of Atomic Orbitals the atomic structures from the Periodic table of atoms such as C, N and O do not adequately explain how these atoms use orbitals to form bonds. A hyloridizahión model has therefore been developed in order to explain real structures, for example How all the bond lengths and angles are equivalent in $CH_4$(methane) See image for chemical structures Note that s-ohorlats, are spherical and p-orbitals are oval, therefore mixing the two, gies an oblong shape Looking at the atoms that make up water, h2O Each t atom has a single election and is 1s The "O" atom has '8 total electrons and is $1s^2, 2s^2, 2p^2 2p'y2p'z$ The two lone pairs on "O" ($2s^2 and 2p^2x$) there are not the same but they are equivalent in H20, therefore we cannot use this atomic structure of "0" to make water-well have to modify it. Maniputating the Atomic Orbitals of "O" We Can translate the electronic structure to make it easier to see $0=1s^2, 2s^2, 2p^2x, 2p'y, 2p'z \equiv{Energy} \frac{\uparrow{_I}}{\downarrow_{1s}} \frac {\uparrow}{\downarrow_{2s}} \frac {1}{\downarrow_{2p}} (Grand \quad State$ The Hybridization Model "for "O" he losse pairs are not the same here so we need to modify the ground state picture to better match how "O" bonds in Hal! See Image of Chemical Structure The $8p^3$ hybridized orbitale are 14 s-like and 3/4 P-like and therefore their shape looks like this Populating the cortoitals with the elechisme, we now howe Now we have two equivalent love pairs ($sp^3$) and turo half-filled orbitals ($sp^3$) that will make sigma bonds with t atoms is th₂O. There are only three oriental patterns the you need to know in the organic Chemistry sequence See Image of Chemical Structure, all titled Sp-hybridized See images for all the chemical formulas: ""The $Sp^3$ picture for C, N and O 1. there are no pi-bunds, $sp^2$ hybrid orbitals are used (2) The $Sp^3$ pichure for C-atim, the $sp^3$ orbatas project to the four corners of a regular tetrahedron. 3 camplahythyl "The $sp^2$ pictures fur C, N aned O"" ""The sp hybrid Pichime for C.; N and O"", (all the compounds is show in image) when a pibond what is pibond?, See chemical structure of the formula Characteristics of Homologous Series 1. Members of the series can be represented by a general formula 2. Successwe members differ from each other by - Cth.. The difference between propanol omal ethanol is Cth that has a relative molecular man of 14. 3. Physical Properties change regularly with increasing number of Carbon atoms. The boiling pants of alkohds in Crease from ethanol, propanol to loutanol 4. Member have similar chemical properties because they have similar & same functional group. Eg. Etkamol, propanol cord lontanol under go oxidation to produce carboxylic acids - loss of H atom. 5. Members of the homologous series can be prepared uong the same mettiod, Ethand, propand and butanol can be prepared by hydration of alkene. General Formula General Formula of Sume Classes of Compounds See image for the chemical structure ALKANES The alkeunes or the paraffins are the saturated hychrocarlions. All thae Carbon atoms in an alkane molecule are sp³ bybridized, with tetrahedral geometry around each atom. Many occur naturally, and the main source of the alkanes es petroleum. They have the general formulbox: Cnthanta wrth methane, Hy being the Simplest member. See image for the formula General Methods of Preparation of the Alkanes KT. Hydrogenation of Alkenes $C_nH_{2n} + H_a + Pt, Pd or Ni \longrightarrow C_nH_{2n+2}$ Alkene Alkane Crude Nat-ges Cocal Thes is by far the most vimportant of the methods. auribable for the preparation of alkonice. Kilken shaken under a slight pressure of hydrogen gas in the presence of a small amount of catalyst, alkenes are converted smoothly and quantitatively is to alkanes of the same Carbon Skeleton eng See image for the formula Reduchon by metal and acid (is fix where X. P. α, Bror1) In these reactions the halogen (x) of the halides is replaced toy bychrogen (H). There are two mettords: See image for the formula and compound Hychrolysis of Grignard reagent Eg $RX+Mg \longrightarrow RMgX\xrightarrow[H_2O]{} RH$ See image for the formula and compound Industrial Source/Occurence of of alkoutes includes , natured gas and petroddekeim, March gas and decompositions of organic matter. Physical Properties of Alkanes Methane and ethane are odourless, many of the higher lydrocarbons have districtime odours. The boiling points, matting points and densities of Some - alkanes vary in a regular manner. See image for the formula and compound The alkanes from Arethane to bitkine are jases at room temperature, pentane biols just above room temperature and the remaining alkanes shans regu bir increase in boiling point with each maltiylene int. This regulinty of physical properties Heims foron a régulanty is stricture"" See chemical structure in image Assignment: Find out the Boiling Points, Metting Pant and Densitities of the first 20 n-alkanes. The alkanes are soluble in non-polar solvents such as benzene, ether and chloroform and is soluble in unter and other bighly polar Solvents. They are also considered as solvents, eg hexane: The density in creases with size of alkerme, but tends to level off at about 0.8 thus all alkanes are less dense than water. Reachins of Alkaneshe alkanes ane la gente inseactive when compared to other families of organic compounds because the alkanes have no unshared pairs of elections no very polarlands,. and back i binds, no regions of liighly exposed electron density; Assignenent - Read Up Inductive Effect, Mesomeric effect; Steric Effect, Electrometric effect, Hyperconjugation Electronic Concepts in Organic Chemistry.When alkanes react, a certain sites is a likely than others to be invitved. The various possible sites cant be designated as fotoness! See chemical structure in image" Alkanes undergo combushin reaction completely to form op and theo See image for the formula and compound