Achem5
ORGANIC CHEMISTRY

organic chem: study of C cpds found in living organisms
carbon cpds: inorganic (carbonate CO32-, CO2,CO) + organic (methane, ethanol, ethanoic acid)
carbon atoms join w/ one another by covalent bonds > organic cpds w/ various C lengths
C atoms tetracovalent (4 bonds) in single (sp3-hybridised), double (sp2-hybridised) & triple bonds (sp3-hybridised)

Functional group = an atom or a group of atoms which give organic cpds their characteristic chemical properties
Homologous series: sets of organic cpds based on functional groups
Characteristics of homologous series- all members (homologues):
-can be represented by a general molecular formula & -have same functional groups > same properties

Homologous series of organic compounds
HOMOLOGOUS SERIES GENERAL FORMULA FUNCTIONAL GROUP
HYDROCARBONS
Aliphatic hydrocarbons
-alkanes CnH2n+2 (n=1,2,..) none (saturated cpd as all C atoms are sp3-hybridised)
-alkenes CnH2n (n=2,3,..) C-C double bond (unsaturated hydrocarbon)
-alkynes CnH2n-2 (n=2,3..) C-C triple bond (unsaturated hydrocarbon)
Aromatic hydrocarbons
Arenes (Alkylbenzenes) C6+nH6+2n (n=0,1..)
-benzene C6H6 benzene ring
-methylbenzene C6H5CH3 -phenyl group ( CH5) -methyl group (-CH3)
HALOGENO COMPOUNDS
-Halogenoalkanes (aliphatic cpd) CnH2n+1X (n=1,2..)
(X=halogen atom)		 halogen group X (chloro, bromo, iodo group)
-Halogenobenzene (aromatic cpd) C6H5X (X=Cl/Br/I) -phenyl group(C6H5) -halogenogroup X (-Cl/-Br/-I)
HYDROXY COMPOUNDS contain -OH group
-Aliphatic monohydric alcohol CnH2n+2O (n=1,2..) or
CnH2n+1OH (n=1,2..)		 hydroxy group (-OH)
-Phenol C6H5OH phenolic group (C6H5OH)
CARBONYL COMPOUNDS   contain carbonyl group (-CO-)
-Aldehydes (Alkanals) CnH2nO (n=1,2..) or
CnH2n+1CHO (n=0,1..)		 aldehyde group (-COH)
-Ketones (Alkanones) CnH2nO (n=3,4..) or
CmH2m+1COCnH2n+1
(m,n=1,2..)		 ketones group (-C-CO-C-)
MONOCARBOXYLIC ACIDS contain carboxylic group (-COOH)
Aliphatic monocarboxylic acid
-Alkanoic acid CnH2nO2 (n=1,2..) or
CnH2n+1COOH (n=0,1..)		 carboxylic group (-COOH)
Aromatic monocarboxylic acid
-Benzoic acid C6H5COOH -carboxylic group (-COOH) -phenyl group (-C6H5)
ACID DEVIRIVATIVES organic cpds from acids by replacing -OH group of acid by other groups
-Esters (Alkylalkanoates) CnH2nO2 (n = 2,3..) or
CmH2m+1COOCnH2n+1O
(m=0,1,.. n=1,2..)		 ester group (-COOC-)
-Acid chloride (alkanoyl chloride) CnH2n+1COCl (n=1,2..) acid chloride group (-COCl)
NITROGEN COMPOUNDS
Amines
-Aliphatic primary amines CnH2n+1NH2 (n=1,2..) amino group (-NH2)
-Aromatic primary amines -phylamines C6H5NH2 -amino group (-NH2) -phenyl group (C6H5)
-Amides CnH2n+1CONH2 (n=0,1..) amide group (-CONH2)
-Alkanonitriles CnH2n+1CN (n = 1,2..) cyano group (-CN)
-Amino acids NH2CH[]COOH
([] = varying (group of) atoms) 		-amino group (-NH2) -carboxylic group (-COOH)
-Proteins ~NHCHC(=O)NHCH~ amide group (-NHC=O-) (peptide group-for proteins only)

The IUPAC (Geneva) system of nomenclature (naming organic cpds)
longest chain rule: longest continuous chain of C atoms selected > named according to parent alkane
lowest # for substituents: C atoms in parent chain numbers s.t. position of any substituents has the lowest #
prefixes: names of substituents named alphabetically (substituent position number precedes substituent prefix)
lowest # rule for functional group: C atoms numbered s.t. functional groups have lowest position # (disregard lowest # for substituents rule)
lowest # given preference: principal functional group > double bond / triple bond > substituent
preference of functional groups: acid > acid derivatives > aldehyde > nitrile > ketone > alcohol > amine > ether > ethene > ethyne

Isomerism [(in)organic cpds]
isomerism: structural isomerism + stereoisomerism
stereoisomerism: cis/tran isomerism (geometrical isomerism) + optical isomerism
Structural isomerism-cpds w/ same molecular formula, but diff structural formula
Stereoisomerism-cpds w/ same molecular & structural formula, but diff spatial arrangement of atoms
(1)Cis/trans isomers (geometrical isomers)
-cpds (usually alkenes) w/ same molecular & structural formula, but diff spatial arrangement due to prohibition of free rotation about C=C double bond, only occurs in alkenes w/ 2 similar groups attached to diff double-bond C atom, w/ formula

(will not occur when 2 similar groups attached to same double-bond C atom) (cis isomers: similar groups on same side of double bond, trans isomers: similar groups on diff sides of double bond)

(2)Optical isomers (enantiomers)
-stereoisomers which are non-superimposable mirror images and can rotate plane-polarised light in opposite dirns
-must have asymmetric / chiral C atom: C atom w/ 4 diff atoms/groups attached to it, to allow 2 isomers which are non-superimposable mirror images, molecule w/ chiral C atom: optically active- rotates plane-polarised light
-have identical physical properties (bp, mp, density) + chemical properties (same functional groups)
-1 isomer rotates light to right > (+)isomer (dextro-rotatory), isomer: rotate light to left: (-)isomer (laero-rotatory)
Racemate or racemic mixture
-racemic mixture: mixture w/ equal amts of both (+) & (-) isomers > optically inactive
-formed in lab exps when natural biochemical reactions (which produce (+)/(-) isomer only) reproduced
artificially (nature: one isomer useful > antibiotic,.., other isomer useless)

Mechanism of organic reactions
mechanism of reaction: details through which a reaction occurs
overall reaction: reactants > products, mechanism: reactants > intermediate 1 > intermediate 2 >..>products
types of reagents in organic reactions: free radical, electrophile, nucleophile
substrate(organic cpd) + reagent (attacking species) > products

Free radical: atom of group of atoms w/ an unpaired valence e- (single e-), it is a reactive species
in reaction: pairs which another unpaired e- to form a covalent bond
Electrophile: e- deficient species (also a Lewis acid), usually +ve charge
in reaction: adds to electron-rich carbon centre > cov bond
Nucleophile: e- rich species (also a Lewis base), neutral or -ve charge & has > 0 lone pairs of e-s
in reaction: adds to electron-deficient carbon centre & shares lone-pair of valence e-s > cov bond

Breaking of covalent bonds
Homolytic fission: cov bond broken > atoms retain 1 unpaired valence e- > free radicals formed
Heterolytic fisson: cov bond broken > electrophile(cation) + nucleophile(anion) formed

Types of organic reactions: addition, substitution, elimination, redox reaction, hydrolysis
Type of reaction reagent type of mechanism typical example
substitution free radical free radical substitution chlorination of methane CH4 + Cl2 >(UV light)> CH3Cl+ HCl
substitution electrophile electrophile substitution nitration of benzene C6H6 + HNO3 >(conc H2SO4+HNO3, ~10°C)> C6H5NO2 +H2O
substitution nucleophile nucleophile substitution hydrolysis of bromoethane CH3CH2Br + NaOH >(heat)> CH3CH2OH + NaBr
addition electrophile electrophile addition bromination of ethene CH2CH2 + Br2 > CH2BrCH2Br
addition nucleophile nucleophile addition addition of HCN to propanone CH3COCH3 + HCN > CH3C(CN)(OH)CH3



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