Introduction to Organic chemistry-converted PDF

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IUPAC NOMENCLATURE OF ORGANIC COMPOUND AND ISOMERISM...

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Organic chemistry Organic chemistry is the branch of chemistry which deals with study of carbon compounds The simplest organic compounds containing carbon and hydrogen only are called hydrocarbons According to Vital force theory organic compounds cannot be prepared in the lab artificially Urea is the first organic compound prepared in the lab by Wohler NH4CNO → NH2-CO-NH2 The first organic compound prepared from its elements in the lab is CH3COOH it was prepared by Kolbe’s The second organic compound prepared from its elements in the lab is CH4 it was prepared by Berthelot

Catenation: Self inter linkage of same atom of elements to form chain or Branched chains or rings are called catenation. Only one carbon form the above one million compounds with another elements due to a. Catenation capacity of carbon b. Tetravalence of carbon c. Carbon has tendency to form multiple bond ( C=C, C≡C) CH4 named has methane, fair damp, Marsh gas. Same compound has different name to avoid this confusion. Worldwide chemists meet in Geneva to propose guide lines under IUPAC ( international union of pure and applied chemistry) IUPAC name : prefix + Root word + primary suffix + secondary suffix Prefix is indicate substituent Group prefix -Cl chloro -Br Bromo -I Iodo -F Fluoro -NO2 nitro -NO nitroso -CH3 methyl -CH2-CH3 ethyl

Root word : It indicate the number of carbon atoms in the chain No of carbon atoms in the chain 1C 2C 3C 4C 5C 6C 7C 8C 9C 10C

Root word Meth Eth prop But pent Hex Hept Oct Non Dec

Primary suffix: It is indicate the nature of carbon chain Nature of carbon chain Primary suffix Saturated hydrocarbon (alkane) C-C ane Unsaturated alkene (C=C) ene Unsaturated alkyne ( C≡C) Yne Secondary suffix: it is indicate the functional group Functional group Secondary suffix Alcohol (-OH) Ol Aldehyde (-CHO) Al Ketone (C=O) One Carboxylic acid (-COOH) oic acid Cyanide Nitrile Isocyanide Carbyl amine Alkane: Carbon- carbon between single bond containing saturated hydrocarbons are called alkanes.The general formula of alkane is CnH2n+ 2. In alkanes all carbon atoms are involve in Sp^3 hybridization. The geometry is tetrahedral. The bond angle is 1090 281 Alkane CH4 CH3-CH3 CH3-CH2-CH3 CH3-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH3

IUPAC name Methane Ethane Propane Butane Pentane Hexane Heptane

CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

Octane Nonane Decane

Alkyl : It is represented with R- . The named has alkyl R-H → RCH4 → CH3CH3-CH3→ CH3-CH2-CH3 Methyl -CH2-CH3 Ethyl -CH2-CH2-CH3 Propyl -CH2-CH2-CH2-CH3 Butyl Isoalkane : In the carbon chain second carbon atom has one methyl group(branch) is called isoalkane. H3C

CH

CH3

CH3 H3C

CH

Isobutane CH2 CH3

CH3

isopentane

Neoalkane : In the carbon chain second carbon atom has two methyl groups(Branch) is called neo alkane CH3 H3C

C

CH3

CH3

neo pentane

CH3 H3C

CH2 CH3

C CH3

neohexane

Cylcoalkane: The first carbon atom linked with last carbon atom to form a ring structure is called cycloalkane

cyclopropane

cyclobutane

cyclopentane

Classification of Carbon Atoms 1. On the Basis of Number of C Attached (i) Primary carbon atom: When carbon atom is attached with one other carbon atom only, it is called primary or 1° carbon atom. (ii) Secondary carbon atom :When carbon atom is attached with two other carbon atoms, it is called secondary or 2°carbon atom. (iii) Tertiary carbon atom: When carbon atom is attached with three other carbon atoms, it is called tertiary or 3° carbon atom. (iv) Quaternary carbon atom: When carbon atom is attached with four other carbon atoms, it is called quaternary or 40 carbon atom. Reactivity order of carbon atoms is as follows 3° > 2° > 1°.

Alkene : carbon – carbon between double bond containing unsaturated hydrocarbons are called alkenes The general formula of alkene is CnH2n. In alkene double bonded carbon atoms are involve in Sp2 hybridization. The geometry of molecule is trigonal planar. The bond angle is 1200

Alkene CH2=CH2 CH3-CH=CH2

Common name Ethylene propylene

IUPAC name Eth + ene = Ethene Pro + ene = propene

CH3-CH=CH-CH3 CH3-CH2-CH=CH2

butylene butylene

But +2-ene = 2-butene But + 1-ene = 1-butene

Alkyne : carbon – carbon between triple bond containing unsaturated hydrocarbons are called alkynes. The general formula of alkyne is CnH2n-2 . in alkyne triple bonded carbon atoms are involve in Sp hybridization. The geometry of molecule is linear. The bond angle is 1800 Alkyne HC≡CH CH3-C≡CH CH3-C≡C-CH3

Common name acetylene Propylene Or methyl acetylene Butylenes Or dimethy acetylene

IUPAC name Eth + yne = Ethyne Prop + yne = propyne But + 2-yne = 2-Butyne

Alcohols : Alcohols are represented with R-CH2-OH. The IUPAC name of alcohol is alkanol alcohol CH3-OH CH3-CH2-OH CH3-CH2-CH2-OH

Common name Methyl alcohol Ethyl alcohol Propyl alcohol

IUPAC name Meth + ane + ol = Methanol Eth + ane + ol = Ethanol Prop + ane + ol = propanol

Alkyl halide : Alkyl halides are represented with R-CH2-X . The IUPAC name of alkyl halides is haloalkane Alkyl halide CH3-Cl

Common name Methyl chloride

CH3-CH2-Cl CH3-CH2-CH2-Cl

Ethyl chloride Propyl chloride

IUPAC name Chloro + Meth + ane = chloromethane Chloro+eth + ane =chloroethane Chloro + prop + ane = Chloro propane

Ethers : Ethers are represented with R-O-R. The IUPAC of ether is alkoxy alkane Alkyl + oxygen → alkoxy CH3-(methyl) + O(oxygen) → methoxy CH3-CH2- (ethyl) + O (oxygen) → ehtoxy Ethers are classified into symmetric ethers and unsymmetrical ethers

Symmetric ethers : CH3-O-CH3 , CH3-CH2-O-CH2-CH3 Unsymmetrical ethers : CH3-O-CH2-CH3 , CH3-CH2- O –CH2-CH2-CH3 Ether CH3-O-CH3 CH3-CH2-O-CH2-CH3 CH3-O-CH2-CH3

Common name Dimethyl ether Diethyl ether Methyl ethyl ether

IUPAC name Methoxy methane Ethoxy ethane Methoxy ethane

Alkyl cyanides : Alkyl cyanides are represented with R-CN .The IUPAC name is alkane nitrile Akyl cyanide CH3-CN

Common name Methyl cyanide

CH3-CH2-CN

Ethyl cyanide

CH3-CH2-CH2-CN

Propyl cyanide

IUPAC name Eth+ ane + nitrile= ethane nitrile Prop + ane + nitrile = propane nitrile But + ane + nitrile = butane nitrile

Alkyl isocyanide : Alkyl isocyanides are represented with R-NC . The IUPAC name is alkane carbyl amine. Alkyl isocyanide CH3- NC

Common name Methyl isocyanide

CH3-CH2-NC

Ethyl isocyanide

CH3-CH2-CH2-NC

Propyl isocyanide

IUPAC name Meth + ane + carbyl amine = methane carbyl amine Eth + ane + carbyl amine = ethane carbyl amine Prop + ane + carbyl amine = propane carbyl amine

Carbonyl compounds: C=O is carbonyl group . C=O group containing compounds are carbonyl compounds. Aldehyde and ketones are called carbonyl compounds. Aldehydes : Aldehydes are represented with R-CHO . The IUPAC name is alkanal Aldehyde HCHO CH3-CHO CH3-CH2-CHO

Common name formaldehyde acetaldehyde propanadehyde

IUPAC name Meth + ane + al = methanal Eth + ane + al = ethanal Prop + ane + al = propanal

O

Ketones : The ketones are represented with Ketone O H3C

R

C

R . The IUPAC name is alkanone .

Common name Dimethyl ketone

IUPAC name Prop + ane + one = 2propanone

Methyl ethyl ketone

But + ane +2- one = 2butanone

C CH3

O H3C

C CH2 H3C

Amines :

in NH3 one hydrogen atom is replaced by alkyl(R-) group is called primary amine

NH3 + R-X → R-NH2 + HX R-NH2 is primary amine in NH3 two hydrogen atoms are replaced by two alkyl(R-) groups is called secondary amine NH3 + 2R-X → R2NH + 2HX R2NH is secondary amine in NH3 three hydrogen atoms are replaced by three alkyl(R-) group is called tertiary amine NH3 + 3R-X → R3N + 3HX R3N is tertiary amine Primary amine : primary amine is represented with R-NH2. The IUPAC name is alkanamine Primary Amine CH3-NH2 CH3-CH2-NH2

Common name Methyl amine Ethyl amine

IUPAC name Methanamine Ehanamine

Secondary amine: Secondary amine is represented with R2NH . The IUPAC name is N- alkyl alkanamine

Secondary amine CH3-NH-CH3 CH3-NH-CH2-CH3

Common name Dimethyl amine Methyl ethyl amine

IUPAC name N- methyl methanamine N- methyl ethanamine

Tertiary amine: Tertiary amine is represented with R3N. The IUPAC name is N,N-dialkyl alkanamine ( same alkyl groups) , N- alkyl , N-alkyl alkanamine ( different alkyl groups) Tertiary amine H3C

H3C

CH3

Common name Trimethyl amine

IUPAC name N, N-dimethyl methanamine

CH3 N CH3

Dimethyl ethyl amine

N,N-dimethyl ethanamine

Diethyl methyl amine

N-methyl , N-ethyl ethanamine

N

H2C H3C

N

CH2 CH3 CH3 CH2 CH3

Carboxylic acid: carboxylic acid is represented with R-COOH. The IUPAC name is alkanoic acid Carboxylic acid HCOOH

Common name Formic acid

CH3COOH

Acetic acid

CH3-CH2-COOH

Propionic acid

IUPAC name Meth + ane + oic acid = methanoic acid Eth + ane + oic acid = Ethanoic acid Prop+ane +oic acid = propanoic acid

Carboxylic acid derivatives : Esters : Carboxylic acid react with alcohol to gives esters. Ester is represented with RCOOR. The IUPAC name is alkyl alkanoate Esters CH3COOCH3 CH3COOCH2CH3

Common name Dimethyl ester Ethyl methyl ester

IUPAC name Methyl ethanoate Ethyl ethanoate

Acid halides : Acid halide is represented with R-COX . In the IUPAC name parent carboxylic acid oic acid is replaced by yl halide . The IUPAC name is alkanyl halide

Acid halide CH3-COCl CH3-CH2-COCl

Common name Acetyl chloride Propionyl chloride

IUPAC name Ethanyl chloride Propanyl chloride

Acid amide: Acid amide is represented with R-CONH2. In the IUPAC name parent carboxylic acid oic acid is replaced by amide. The IUPAC name is alkanamide. Acid amide CH3-CONH2 CH3-CH2-CONH2

Common name Acetamide Propionamide

IUPAC name ethanamide Propanamide O R O

Acid anhydrides : Acid anhydride is represented with

R

O . In the IUPAC name parent

carboxylic acid acid is replaced by anhydride .

Anhydride O H3C

Common name Acetic anhydride

O H3C

O

Classification of Organic Compounds

IUPAC name Ethanoic anhydride

IUPAC rules for Name of organic compounds: Longest carbon chain: More number of carbon atoms containing chain is called longest carbon chain of parent chain. First select the longest carbon chain. CH3 H3C

CH

CH3 CH2 CH2 CH3

H3C

CH

CH2 CH2 CH3

2. Numbering for the carbon atom in the longest carbon chain or parent chain. Functional group, substituent and multiple bonds get least number. CH3 H3C

CH CH2 CH2 CH3

5

4

3

2

4- methyl pentane

1

( wrong) CH3 H3C 1

CH CH2 CH2 CH3 2

3

4

5

2 –methyl pentane

( Correct )

3. When the same substituent is present on the same carbon atom more than once then the position of the substituent is repeated number of times as per the repetition of the substituent.

CH3 H3C 1

C 2

CH2 CH2 CH3 3

4

5

CH3

2,2-dimethyl pentane

4. if the carbon chain contains two or more than two identical substituents then di,tri, tetra etc prefixes are used to indicate the number of such substituents. CH3 CH3 H3C 1

C

CH

CH2 CH3

2

3

4

5

CH3

2,2,3-trimethyl pentane

5. if a number of different groups are attached to the parent chain then the naming is done in two ways. According to IUPAC rules name is given to the compound following the increasing order of complexity (size) of the group . According to the chemical abstract system (CA method) alphabetical order followed. CH3 CH3 CH2 H3 C 1

CH CH 2

3

CH2 4

CH2 CH3 5

6

2-methyl-3-ethylhexane (IUPAC method) 3-ethyl-2-methylhexane ( CA method)

6. Lowest sum rule : The longest possible continuous carbon chain selected . The numbers are given to carbon atoms in it from left to right or right to left starting from 1 so that on adding the numbers of all carbon atoms at which the substituents and functional groups are present it should give lowest sum possible.

CH3 H3C 6

C

CH

5

4

Cl

Cl

CH2 CH2 3

2

CH3 1

If numbering from right to left sum is 4 + 5 + 5 = 14 ( wrong) CH3 H3C 1

C

CH

2

3

Cl

Cl

CH2 CH2 4

5

CH3 6

If numbering from left to right sum is 2 +2 +3 = 7 . it is lowest sum ( Correct) 2,3-dichloro-2-methyl hexane 7. The functional group carbon to the lowest number CH3 H3C 1

CH

CH2

CH2 CH2 OH

2

3

4

5

2- methyl -5-pentanol ( Wrong)

CH3 H3C 5

CH

CH2

4

3

CH2 CH2 OH 2

1

4-methylpentanol ( correct )

8. Carboxylic acid , carboxylic acid derivatives and aldehydes are chain terminating groups. They are gives first position. CH3 H3C 1

C 2

CH2 CH2 COOH 3

4

5

CH3

2,2-dimethyl - 5- pentanoic acid ( wrong)

CH3 H3C 5

C 4

CH2 CH2 COOH 3

CH3

2

1

4,4-dimethylpentanoic acid ( correct)

9. if more than two different functional groups the highest priority functional group is taken as factional group and the lowest priority group is taken as substituents. Priority order of functional groups is as follows: No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Functional group -COOH -SO3H -COOR -COX -CONH2 -CN -CHO -C=O -OH -SH -NH2 -C=C-C≡C-NO2 -NO -X

prefix corboxylic Sulphonic acid Alkoxyl carbonyl haloformly carbamoyl cyano formyl oxo hydoxy mercapto amino ene yne nitro nitroso halo

OH H3C 5

CH

CH2

CH2 COOH

3

4

2

1

4-hydroxy-pentanoic acid O H3C

C

5

CH2

4

CH2

3

CHO

2

4-oxopentanal

1

Write the IUPAC name of the following compounds CH3 H3C 1

C

CH2

2

CH2 CH3

3

4

5

CH3

2,2-dimethylpentane

H3C

CH

CH

CH

CH

2

3

4

5

H3C

CH2 CH2 CH2 C

1

6

5

4

3

2

CH3 6

2,4-hexadiene or hex-2,4-diene

CH 1

1-hexyne

NH2 H3C 5

CH

CH2 CH2 3

4

H2C

CH

CH

2

3

1

COOH

2

1

4- amino-pentanoic acid

CH2 4

1,3-butadiene or but-1,3-diene

O H3C

C

5

CH2

4

3

CH2

COOH 1

2

4-oxo-pentanoic acid

CH3

methyl cyclobutane Cl Cl

1,1-dichlorocyclohexane H3C

C

C

2

3

H3C

CH

CH2

1

3

2

CH3 4

2-butyne

CH3 1

CH H3C

4

CH2 5

H2C 6

CH3

3,4-dimethylheptane

7

OH H3C 4

CH 3

CH2 2

CHO 1

3-hydroxybutanal

Writing the structure if the name of a carbon compound is given

1. Observe the root word and write the continuous carbon chain. 2. numbering the carbon atoms in the continuous carbon chain either right side or left side 3. Write the functional group, multiple bonds and substituent at respective carbon atoms. 4. Carbon has tetravalency. Attach the required number of hydrogen atoms at each carbon atom to satisfy its valency. Eg: 2- bromopentane Root word is pent C-C-C-C-C Numbering the carbon atoms

C5-C4-C3-C2-C1

Write the substituent at respective carbon atom C5-C4-C3-CBr2-C1 Br

Final satisfy the carbon valence

H3C 5

CH2 4

CH2 3

CH 2

CH3 1

Eg: 2-methylhexnoic acid C-C-C-C-C(CH3)-COOH CH3-CH2-CH2-CH2-CH(CH3)-COOH Eg: 2-pentene C-C-C-C-C C-C-C=C-C CH3-CH2-CH=CH-CH3 Cleavage of covalent bonds: The cleavage of a covalent bond can take place in two different ways. The bond breaking generally depends on the nature of polarity of the bond nature of attacking reagent and conditions of the reaction. Homolytic bond fission or Homolysis: In homolysis the covalent bond is broken in such a way that each resulting species gets its own electron. This leads to the formation of odd electron species known as free radical. Homolysis is favored by low polarity, in gas phase or in the presence of non polar solvents (CCl4, CS2), presence of peroxides, high temperature or light of suitable frequency.

A : B → A. + B.

The stability of free radicals Tertiary free radical > secondary free radical> primary free radical>methyl free radical (CH3)3C. > (CH3)2CH.> CH3-CH2. > CH3. In free radical central atom carbon involve in Sp2 hybridization. The geometry of trigonal planar. Heterolytic bond fission or Heterolysis: In heterolysis the covalent bond is broken in such way that one species( i.e less electronegative) is deprived of its own electron, while the other species gains both of the electrons A:B → A+ + B-

Thus formation of opposite charged species takes place. In case of organic compounds, if positive charge is present on the carbon is termed as carbocation or carbonium ion. In case of organic compounds, if negative charge is present on the carbon is termed as carbanion. The stability of carbocations or carbonium ions Tertiary carbonium ion> secondary carbonium ion> primary carbonium ion > methyl carnoium ion (CH3)3C+ > (CH3)2CH+> CH3-CH2+ > CH3+ In carbonium ion central atom carbon involve in Sp2 hybridization. The geometry of carbonium ion is trigonal planar. The negatively charged carbon is termed as c...