Chapter 19 Carboxylic Acids and their derivatives Part 2- Chemistry free study material by TEACHING CARE online tuition and coaching classes

Chapter 19 Carboxylic Acids and their derivatives Part 2- Chemistry free study material by TEACHING CARE online tuition and coaching classes

File name : Chapter-19-Carboxylic-Acids-and-their-derivatives-Part-2.pdf

 

 

(ix) Reaction with Glycerol : At 100° – 110°C, formic acid is formed. At 260°, allyl alcohol is formed.

  • Uses : Oxalic acid (Polyprotic acid) is used,
    • In the manufacture of carbon monoxide, formic acid and allyl
    • As a laboratory reagent and as a standard substance in volumetric analysis.
    • In the form of antimony salt as a mordant in dyeing and calico
    • In the manufacture of
    • For removing ink stains and rust stains and for bleaching straw, wood and
    • In the form of ferrous potassium oxalate as developer in

(5)  Analytical test

  • The aqueous solution turns blue litmus

 

  • The aqueous solution evolves effervescences with

NaHCO3 .

 

  • The neutral solution gives a white precipitate with calcium chloride solution. It is insoluble in acetic

HCO4  ¾¾NH¾4 O¾H ®(NH 4 )2 CO4  ¾¾CaC¾l2  ®  CaCO4

 

Oxalic aicd

Amm.oxalate

Calcium oxalate

 

  • Oxalic acid decolourises hot potassium permanganate solution having dilute sulphuric

 

  • With hot

H 2SO4 , it evolves carbon monoxide which burns with blue flame.

 

 

Malonic Acid or Propane-1,3-Dioic Acid :

CH 2

COOH COOH

or CH

2 (COOH)2

or (C3

HO4 )

 

The acid occurs as calcium salt in sugar beet. It was so named because it was first obtained from malic acid (hydroxy succinic acid) by oxidation.

2
2
  • Methods of Preparation : From acetic acid

 

CH 3

COOH ¾¾C¾l2  ® CH

P

2ClCOOH ¾¾KC¾N(A¾q¾.) ® CH

CNCOOH ¾¾H2O¾H¾+   ® CH

COOH COOH

 

Acetic acid

Chloroacetic acid

Cyano acetic acid

Malonic acid

 

(2)  Physical Properties

  • It is a white crystalline
  • It’s melting point is 135°C.
  • It is soluble in water and alcohol but sparingly soluble in

(3)  Chemical Properties

  • Action of heat

 

  • Heating at 150°C :

CH 2 (COOH)2  ® CH 3 COOH + CO2

 

 

 

  • Heating with P O :

|      |

O =  C –      –

= O ¾¾P O¾® O = C = C = C = O+ 2H  O

 

2  5                           C   C                    2   5                                                                            2

|        |                          heat            Carbon suboxide

  • Reaction with aldehyde : With aldehydes, a-b unsaturated acids are

 

RCH = O+ H C

COOH ¾¾Pyr¾idin¾e ® RCH  = CHCOOH+ H

O + CO

 

Aldehyde         2

COOH

heat

ab unsaturated acid                   2               2

 

  • Uses : Its diethyl ester (malonic ester) is a valuable synthetic reagent for preparation of a variety of carboxylic

 

 

 

 

Succinic Acid or Butane-1,4-Dioic Acid :

CH2COOH

|                     or (CH 2 )2 (COOH)2 or (C4 HO4 )

CH2COOH

 

It was first obtained by the distillation of yellow fossil, resin, amber and hence its name (Latin, Succinum = amber). It is also formed in small amount during the fermentation of sugar.

(1)  Methods of Preparation

 

 

  • From ethylene :

CH2

 

¾¾B¾r

® CH2Br ¾¾NaC¾N  ® CH2CN ¾¾H  O¾H¾C¾l  ® CH2COOH

 

||

CH2

Ethylene

2           |

CH2Br

Ethylene bromide

|                2

CH2CN

Ethylene cyanide

 

CHCOOH

|

CH2COOH

Succinic acid

 

CH2COOH

 

  • From maleic acid [catalytic reduction]: ||

+ H2  ¾¾Ni ®|

 

 

Note : ® This is an industrial method.

CHCOOH

 

 

CHOHCOOH

heat

CH2COOH

 

CH2COOH

 

 

CHOHCOOH

 

  • Reduction of tartaric acid or malic acid : |

¾¾H¾I ® |

¬¾HI ¾  |

 

 

 

(2)  Physical properties

  • It is a white crystalline It melts at 188 o C

CHOHCOOH

Tartaric acid

P            CH2COOH

Succinic acid

P            CH2COOH

Malic acid

 

  • It is less soluble in It is comparatively more soluble in alcohol.
  • Chemical Properties : Succinic acid gives the usual reactions of dicarboxylic acid, some important reactions are :
  • Action of heat : At 300°C

 

CH2COOH

|

CH2COOH

Succinic acid

¾¾300¾°¾C ®

(– H2O)

CH2CO

|               O

CH2CO

Succinic anhydride

CH2COOH

 

 

CH2COONH4

 

 

CH2CONH2

 

 

CH2CO

 

  • With ammonia : |

¾¾NH¾3  ®|

¾¾he¾at ® |

¾¾he¾at ®|                NH

 

CH2COOH

CH2COONH4

Ammonium succinate

H2O

CH2CONH2

Succinamide

  • NH3

CH2CO

Succinimide

 

 

  • Reaction with Br2 :

CH2 –CO

|

CH2 –CO

NH + Br2  ¾¾NaO¾H ® |

N Br + HBr

 

CH2 –CO

Succinimide

 

  • Reaction with ethylene glycol

HOOC – (CH 2 )2 – CO OH + H OCH2  – CH 2 O

H2O

C

CH2 –CO

N -bromosuccinimide (N.B.S)

 

 

OC – (CH 2 )2 – CO OH + …….

 

HOOC – (CH2 )2 – CO – [-OCH2  – CH2O OC – (CH2 )2  – CO-]n  OH + H2O

Polyester

When sodium or potassium salt in aqueous solution is electrolysed, ethylene is obtained at anode.

  • Uses : It finds use in volumetric analysis, medicine and in the manufacture of dyes, perfumes and polyester

 

 

 

 

Adipic Acid or Hexane-1,6 –Dioic Acid :

CH2CH2COOH

|                              or   (CH2)4 (COOH)2

CH2CH2COOH

or (C6 H10O4 )

 

It was first obtained by the oxidation of fats (Latin, adeps = fat.)

(1)  Methods of Preparation

  • From benzene

 

 

 

H2                                  O2

 

OH

HNO3

O

 

HNO3                     HOOC – (CH2)4

 

– COOH

 

 

Benzene

Catalyst

Cyclohexane

H3BO3, heat

 

Cyclohexanol

SeO3

Cyclohexanone

Adipic acid

 

 

Note : ® It is an industrial method.

  • From tetrahydrofuran (THF)

CH2 –CH2

 

|

CH2

O

THF

|

CH2

  • 2CO + HOH ® HOOC – (CH 2 )4 – COOH

Adipic acid

 

(2)  Physical Properties

  • It is a white crystalline Its melting point is 150°C.
  • It is fairly soluble in alcohol and ether but less soluble in

(3)  Chemical Properties

It shows all the general reaction of dicarboxylic acids.

H
  • Action of heat

2

 

 

HOOC(CH2)4

Adipic acid

COOH

 

heat

300°C

C

H2C

|

H2C

C H2

C = O + CO2 + H2O

 

Cyclopentanone

  • Formation of Nylon-66 [Reaction with hexa methylene diamine]

nH 2 N(CH 2 )6 NH 2 + nHOC– (CH 2 )4 – COH

 

hexamethylene diamine

||

O

nH2O

||

O

adipic acid

 

H                        H   O                        O

|                          |      ||                         ||

– (- N – (CH2 )6 – N C– (CH2 )4 – C -)n  

nylon-66

 

  • Uses : It is used in the manufacture of several

Unsaturated Acids : When the double bond presents in the carbon chain of an acid is called unsaturated acid.

 

 

Example: CH 2 = CH COOH+ H CCOOH

 

Acrylic acid

||

HCCOOH

Maleic acid

 

Acrylic Acid or Prop-2-Enoic Acid :

  • Methods of Preparation

CH2

CH 2 = CH COOH

 

CH2Br

or (C3 HO2 )

 

CH2Br

 

C H

CH2

 

||

  • From allyl alcohol : C H

¾¾B¾r2  ®

|

C HBr

¾¾HN¾O¾3  ®

|

C HBr

¾¾Zn ® ||

 

|

CH2OH

|

CH2OH

[O]

|

COOH

heat

|

COOH

 

  • By oxidation of acrolein :

CH 2  = CHCHO + [O] ¾¾AgN¾O¾3  ® CH 2  = CHCOOH

NH4 OH

 

  • From propionic acid :

CHCHCOOH ¾¾BrP ® CHCHBrCOOH ¾¾Alc¾.KO¾H ® CH 2  = CHCOOH

 

Propionic acid

HVZ reaction

a -Bromopropionic acid

 

  • By heating b-hydroxy propionic acid :

C H 2 – CH 2  – COOH ¾¾ZnC¾l2  ® CH 2  = CHCOOH

 

 

 

  • From vinyl cyanide

HC º CH+ HCN ¾¾CuClH¾Cl ® CH

|

OH

b -hydroxy propionic acid

 

 

= CHCN ¾¾H+ ¾HO ® CH

heat, –H2O

 

 

 

 

= CH COOH

 

Acetylene

90°C

2                                                          2

Vinyl cyanide

 

2
  • From ethylene cyanohydrin

 

CH 2

  • CH 2

¾¾+HC¾N ® C H 2

|

  • CH 2
  • CN ¾¾Con¾c.H¾2SO¾4 ® CH 2

heat –H2O

= CHCN ¾¾H+ ¾HO ® CH

= CHCOOH

 

O

Ethylene oxide

OH

Ethylene cyanohydrin

Vinyl cyanide (acrylonitrile)

 

Industrial method : This is a new method of its manufacture.

CH  º CH + CO + HO ¾¾Ni(C¾O¾)4  ® CH 2  = CHCOOH

(2)  Physical Properties

  • It is colourless pungent smelling Its boiling point is 141°C.
  • It is miscible with water, alcohol and
  • It shows properties of an alkene as well as of an

(3)  Chemical Properties

 

  • With nascent hydrogen (Na and C2H5OH) :

CH 2  = CHCOOH + 2[H] ¾¾Ni ® CHCHCOOH

 

  • With halogens and halogen acids : Markownikoff’s rule is not

CH 2  = CHCOOH + Br2  ¾¾CC¾l4  ® CHBrCHBrCOOH

a ,b -Dibromopropionic acid

CH 2 = CHCOOH + HBr ® BrCH 2  – CH 2 COOH

b -Bromopropionic acid

  • Oxidation : In presence of dilute alkaline KMnO4.

CH 2   = CHCOOH + [O] + H 2 O ® CH 2 OHCHOHCOOH

Glyceric acid

Note : ® On vigorous oxidation, oxalic acid is formed.

 

 

  • Salt formation :

CH 2 = CHCOOH + KOH ® CH 2  = CHCOOK + + H 2 O

 

 

 

 

2CH 2 = CHCOOH + Na2 CO3  ® 2CH 2  = CHCOONa + + H 2 O + CO2

Sodium acrylate

 

  • Ester formation :

CH 2  = CHCOOH + HOCH5  ¾¾Con¾c.H¾2SO¾4  ® CH 2  = CHCOOCH5

 

 

  • With PCl5 :

H2O

CH 2  = CHCOOH + PCl5  ® CH 2  = CH COCl

Acryl chloride

Ethyl acrylate

 

  • Uses : Its ester are used for making plastics such as Lucite and

 

The molecular formula of the simplest unsaturated dicarboxylic acid is HOOC.CH = CH.COOH This formula,

however represents two chemical compounds, maleic acid and fumaric acid, which are geometrical isomers.

 

H CCOOH

||

HCCOOH

Cis-form (Maleic acid)

(1)  Methods of Preparation of Maleic Acid

HOOC CH

||

HCCOOH

Trans-form (Fumaric acid)

 

2               ||
  • By catalytic oxidation of 2-butene or benzene

 

CHCH3

||

  • 30  ¾¾V2O¾5  ® CHCOOH
  • 2H 2 O

 

CHCH3

2-Butene

400°C

CHCOOH

Maleic acid

 

C  H  + 9 O

CHCO

¾¾V2O¾5  ®

O       H2O  H +

CHCOOH

 

6     6             2                    ||

¾¾¾¾®||

 

Benzene    2

400o C

CHCO

Maleic anhydride

CHCOOH

 

  • From malic acid :

CH(OH)COOH

CHCOOH

CHCO

CHCOONa             +

CHCOOH

 

|                       ¾¾he¾at ®||

¾¾he¾at ® ||

O ¾¾NaO¾H ® ||

¾¾H  ¾HO ® ||

 

CH2COOH

Malic acid (Hydroxy succinic acid)

H2O

CHCOOH

Maleic acid (intermediate)

H2O

CHCO

Maleic anhydride

boil

CHCOONa

Sodium salt

CHCOOH

Maleic acid

 

(2)  Methods of Preparation of Fumaric Acid

HCCOOH

HOOCCH

 

  • From maleic acid :

||

HCCOOH

Maleic acid

¾¾H¾Cl ®

boil

||

HCCOOH

 

  • By oxidation of furfural with sodium chlorate

 

HC              CH

||         ||

HC              CCHO

O

+ 4[O] ¾¾NaC¾lO¾3  ®

HOOCCH

||

HCCOOH

  • CO2

 

  • By heating malic acid at about 150°C for long time

 

CH(OH)COOH

|

CH2COOH

Malic acid

¾¾he¾at ®

150°C, – H2O

HOOCCH

||

HCCOOH

 

 

 

  • By heating bromosuccinic acid with alcoholic potash : By heating bromosuccinic acid with alcoholic

 

CH2COOH

|

CH.(Br)COOH

(4)  Physical Properties

¾¾Alc.¾KO¾H  ®

HOOCCH

||

HCCOOH

  • KBr + H 2O

 

  • Both are colourless crystalline Both are soluble in water.
  • The melting point of maleic acid (130.5°C) is lower than the melting point of fumaric acid (287°C).

(5)  Chemical Properties

Chemically, both the acids give the reactions of alkenes and dibasic acids except that the maleic acid on heating forms an anhydride while fumaric acid does not give anhydride.

 

CHCOOH

||

CHCOOH

CHCO

¾¾he¾at ® ||

CHCO

O+ H 2 O

 

Maleic acid                            Maleic anhydride

Both form succinic acid on reduction with sodium amalgam. They undergo addition reactions with bromine, hydrobromic acid, water, etc. and form salts, esters and acid chlorides as usual. With alkaline KMnO4 solution, they get oxidised to tartaric acid.

 

COOH

|

HCOH

|

HCOH

|

COOH

Tartaric acid (Meso)

 

¬¾Alk¾.KM¾n¾O4 ¾

(Syn-addition)

HCCOOH

||

HCCOOH

Maleic acid (Cis)

 

¾¾Br2w¾at¾er ®

(anti-addition)

COOH

|

HCBr

|

Br CH

|

COOH

(Racemic mixture)

 

COOH

|

HCOH

|

HO CH

|

COOH

Tartaric acid (Racemic mixture)

 

¬¾Alk¾. KM¾n¾O4 ¾

(Syn-addition)

HCCOOH

||

HOOCCH

Fumaric acid (Trans)

 

¾¾Br2w¾at¾er ®

(anti-addition)

COOH

|

HCBr

|

H CBr

|

COOH

((Meso)

 

 

Palmitic, stearic and oleic acids are found in natural fats and oils as glyceryl esters.

They have derived their names from the natural source from which they are prepared by hydrolysis with alkali.

Name of acidsSource Molecular formula
Palmitic acidPalm oil,  CH 3 (CH 2 )14 COOH
Stearic acidStear(meaning CH 3 (CH 2 )16 COOH
 tallow)  
Oleic acidOlive oil.  CH 3 (CH 2 )7 CH  = CH(CH 2 )7 COOH

Palmitic and stearic acids are waxy colourless solids with melting points 64°C and 72°C, respectively. They are insoluble in water but soluble in ethanol and ether. They find use in the manufacture of soaps and candles. Soaps contain sodium or potassium salts of these higher fatty acids.

 

 

 

Oleic acid has low melting point, i.e., 16°C. It is insoluble in water but soluble in alcohol and ether. Besides the reactions of acids, it also gives reactions of alkenes. Two aldehydes are formed on ozonolysis.

 

CH3

(CH

2 )7

CH = CH(CH

2 )7

COOH ¾¾(i)O¾3  ® CH

  • Zn+ H2O 3

(CH

2 )7

CHO + HOOC(CH

2 )7

CHO

 

It is used for making soaps, lubricants and detergents.

  • Difference between oils and fats : Oils and fats belong to the same chemical group, yet they are different in their physical
    • Oils are liquids at ordinary temperature (below 20°C) while fats are semi solids or solids (their melting points are more than 20°C). A substance may be classed as fat in one season and oil in another season or the same glyceride may be solid at a hill station and liquid in plains. Thus, this distinction is not well founded as the physical state depends on climate and
    • The difference in oils and fats is actually dependent on the nature of monocarboxylic acid present in the Oils contain large proportion of the glycerides of lower carboxylic acids, (e.g., butyric acid, caprylic acid and caproic acid) and unsaturated fatty acids, (e.g., oleic, linoleic and linolenic acids) while fats contain a large proportion of glycerides of higher saturated carboxylic acids, (e.g., palmitic, stearic acids).

Lard (fat of hogs) is a solid fat and its composition in terms of fatty acids produced on hydrolysis is approximately 32% palmitic acid, 18% stearic acid, 45% oleic acid and 5% linolenic acid. Olive oil on the other hand, contains 84% oleic acid, 4% linoleic acid, 9% palmitic acid and 3% stearic acid.

(2)  Physical Properties of oils and Fats

  • Fats are solids, whereas oils are
  • They are insoluble in water but soluble in ether, chloroform and
  • They have less specific gravity than water and consequently float on the surface when mixed with
  • Pure fats and oils are colourless, odourless and tasteless but natural fats and oils possess a characteristic odour due to presence of other
  • They have specific melting points, specific gravity and refractive index hence they can be identified by these oil
  • Animal fats contain cholesterol, an unsaturated alcohol, whereas vegetable fats contains phytosterol.
  • Chemical Properties : They give reactions of carbon-carbon double bonds and ester
    • Hydrolysis
  • By superheated steam

 

CH2O

|

C HO

COC17 H35 COC17 H35

CH2OH

C HOH

¾¾+ 3 H¾2¾O ®  |

+ 3C17

H35

COOH

 

|

CH2O

COC17 H35

|

CH2OH

Stearic acid

 

Tristearin

 

  • Base hydrolysis [Saponification]

Glycerol

 

CH2OCOR

|

CH2OH

|

 

C HOCOR + 3NaOH ® C HOH + 3RCOONa

 

|

CH2OCOR

Fat or oil

|

CH2OH

Glycerol

Salt fatty acid (Soap)

 

  • Enzyme hydrolysis : Enzyme like lipase, when added to an emulsion of fat in water, hydrolyses it into acid and glycerol in about two or three

 

 

 

  • Hydrogenation : In the presence of finally divided nickel, the hydrogenation process is called hardening of

 

O

||

CH 2 OC(CH 2 )7 CH  = CH(CH 2 )7 CH3

O

||

 

 

 

 

 

+ 3 H

O

||

CH 2 OCC17 H35

O

||

 

CHOC(CH 2 )7 CH  = CH(CH 2 )7 CH3  ¾¾¾2  ® CHOCC17 H35

Ni,heat

 

O

||

CH 2 OC (CH 2 )7 CH  = CH(CH 2 )7 CH3

Glyceryl trioleate or triolein (Liquid oil)

 

  • Hydrogenolysis [Reduction to alcohol]

O

||

CH 2 – O CC17 H35

O

||

CH 2 OCC17 H35

Tristearin (A solid fat)

 

O

||                                 6 H

CH2OH

|

 

CHOCC17 H35              ¾¾¾2  ® C HOH + 3C17 H35 CHOH

 

 

 

O

||

CH 2  – O CC17 H35

Tristearin

200atm

|

CH2OH

Octadecyl alcohol

 

  • Drying : Certain oils, containing glycerides of unsaturated fatty acids having two or three double bonds have the tendency of slowly absorbing oxygen from atmosphere and undergoing polymerisation to form hard transparent coating. This process is known as drying and such oils are called drying oils. Unsaturated oils such as linseed oil are, therefore, used as medium of paints and
  • Rancidification : On long storage in contact with air and moisture, oils and fats develop unpleasant The process is known as rancidification. It is believed that rancidification occurs due to hydrolysis-oxidation.

(4)  Analysis of oils and fats

  • Acid value : It indicates the amount of free acid present in the oil or fat. It is defined as the number of milligrams of KOH required to neutralize the free acid present in one gram of the oil or fat. It is determined by dissolving a weighed amount of oil or fat in alcohol and titrating it against a standard solution of KOH using phenolphthalein as an
  • Saponification value : It is a measure of fatty acids present as esters in oils and fats. It is defined as the number of milligrams of KOH required to saponify one gram of the oil or fat or number of milligrams of KOH required to neutralize the free acids resulting from the hydrolysis of one gram of an oil or It is determined by

refluxing a Saponification number of fat or oil = 168,000

M

M = molecular mass

  • Iodine value : Iodine value of a fat or oil is a measure of its degree of unsaturation. It is defined as the number of grams of iodine taken up by 100 grams of fat or oil for For a saturated acid glyceride, the iodine value is zero. Thus, the iodine value for a fat is low whereas for oil, it is high. As iodine does not react readily, in actual practice, iodine monochloride is used. Iodine monochloride is known as Wij’s reagent.

 

 

 

  • Reichert-Meissl value, (R/M value) : It indicates the amount of steam volatile fatty acids present in the oil or fat. It is defined as the number of millilitres of 1 N KOH solution required to neutralize the distillate of 5 grams of hydrolysed fat. It is determined by hydrolysing a known weighed amount (5 grams) of the fat with alkali solution and the mixture is acidified with dilute sulphuric acid and steam distilled. The distillate is cooled, filtered and titrated against 0.1 N KOH.
  • Uses
    • Many oils and fats are used as food
    • Oils and fats are used for the manufacture of glycerol, fatty acids, soaps, candles, vegetable ghee, margarine, hair oils,
    • Oils like linseed oil, tung oil, , are used for the manufacture of paints, varnish, etc.
    • Castor oil is used as purgative and codliver oil as a source of vitamins A and D. Almond oil is used in Olive oil is also used as medicine.
    • Oils are also used as lubricants and

(6)  Difference between vegetable oils and Mineral oils

 

PropertyVegetable oilsMinerals oils
1.     Composition

 

 

2.   Source

These are triesters of glycerol with higher fatty acids.

 

Seeds root and fruits of plants.

These            are            hydrocarbons (saturated). Kerosene oil– Alkanes from C12 to C16.

These occur inside earth in the form of petroleum.

3. HydrolysisUndergo hydrolysis with alkali. Form soap and glycerol.No hydrolysis occurs.
4. On adding NaOH and phenolphthaleinDecolourisation of pink colour occurs.No effect.
5. BurningBurns slowlyBurn very readily.
6. HydrogenationHydrogenation occurs in presence of nickel catalyst. Solid glycerides (fats) are

formed.

No hydrogenation occurs.
  • Soaps : Soaps are the metallic salts of higher fatty acids such as palmitic, stearic, oleic, The sodium and potassium salts are the common soaps which are soluble in water and used for cleansing purposes. Soaps of other metals such as calcium, magnesium, zinc, chromium, lead, etc., are insoluble in water. These are not used for cleansing purposes but for other purposes (lubricants, driers, adhesives, etc.)

Ordinary soaps (sodium and potassium) are the products of hydrolysis of oils and fats with sodium hydroxide or potassium hydroxide. The oils and fats are mixed glycerides and thus soaps are mixtures of salts of saturated and unsaturated long chain carboxylic acids containing 12 to 18 carbon atoms. This process always yields glycerol as a byproduct.

 

CH2OCOR1

|

C HOCOR2

|

CH2OCOR3

Triglyceride

CH2OH

|

  • 3NaOH ® C HOH

|

CH2OH

Glycerol

R1COONa

+

  • R2COONa

+

R3COONa

Soap

 

There are three methods for manufacture of soaps :

  • The cold process
  • The hot process
  • Modern process

 

 

 

 

  • Synthetic Detergents : The synthetic detergents or Syndets are substitutes of soaps. They have cleansing power as good or better than ordinary soaps. Like soap, they contain both hydrophilic (water soluble) and hydrophobic (oil-soluble) parts in the

 

 

 

Hydrophobic part

Hydrophilic part

Hydrophobic part

Hydrophilic part

 

Sodium lauryl sulphate (Detergent)                                         Sodium palmitate (Soap)

Some of the detergents used these days are given below:

  • Sodium alkyl sulphates : These are sodium salts of sulphuric acid esters of long chain aliphatic alcohols containing usually 10 to 15 carbon The alcohols are obtained from oils or fats by hydrogenolysis.

CH 3 (CH 2 )10 CH 2  OH + HO SOH ® CH 3 (CH 2 )10 CHOSOOH ¾¾NaO¾H ® CH 3 (CH 2 )10 CHOSOONa

 

Lauryl alcohol

Sulphuric acid

Lauryl hydrogen sulphate

Sodium lauryl sulphate (Detergent)

 

The other examples are sodium cetyl sulphate,

C16 H33 OSO2 ONa

and sodium stearyl sulphate,

 

CH3 (CH 2 )16 CH 2 OSO3 Na . Unlike ordinary soaps, they do not produce OH ions on hydrolysis and thus can be safely used for woollen garments.

  • Sodium alkyl benzene sulphonates : Sodium p-dodecyl benzene sulphonate acts as a good It is most widely used since 1975.

 

 

CH3

(CH 2 )9 CH == CH 2 +

¾¾AlC¾l3  ®

CH3

|

CH3 (CH 2 )9 C H

 

1-Dodecene

Benzene

2-Dodecyl benzene

CH3

 

¾¾(i)H¾2SO¾4  ® CH3

  • NaOH

Sodium dodecyl benzene sulphonate (S.D.S.)

– (CH 2 )9

|

  • C H
  • SO3 Na

 

These long chain alkyl benzene sulphonate (L.A.S.) are most widely used syndets.

  • Quaternary ammonium salts : Quaternary ammonium salts with long chain alkyl group have been used as detergents, g., trimethyl stearyl ammonium bromide.

 

(CH 3 )3 N

Br C18 H37

 

  • Sulphonates with triethanol ammonium ion in place of sodium serve as highly soluble materials for liquid

 

R –            – O

–     é Å

CH

  • CH
  1. OH) ù

 

SO2 êëN H(          2

2          3 úû

 

  • Partially esterified polyhydroxy compounds also acts as

CH2OH

|

C17 H35 COOCH2 – CCH 2 O H

|

CH2OH

Pentaerythritol monostearate

Detergents are superior cleansing agents due to following properties.

  • These can be used both in soft and hard waters as the calcium and magnesium ions present in hard water form soluble salts with Ordinary soap cannot be used in hard water.

 

 

 

  • The aqueous solution of detergents are Hence these can be used for washing all types of fabrics without any damage. The solution or ordinary soap is alkaline and thus cannot be used to wash delicate fabrics.
    • Waxes : Waxes are the esters of higher fatty acids with higher monohydric The acids and

 

alcohols commonly found in waxes are palmitic, cerotic acid

(C25 H51COOH), melissic acid

(C30  H61COOH)

and

 

cetyl alcohol (C16 H33 OH), ceryl alcohol (C26 H53 OH) , myricyl alcohol (C30 H61OH) , etc.

Waxes are insoluble in water but are readily soluble in benzene, petroleum, carbon disulphide etc. Waxes on hydrolysis with water yields higher fatty acids and higher monohydric alcohols.

C15 H31COOC16 H33 + H2O ® C15 H31COOH+ C16 H33 OH

 

Cetyl palmitate

Palmitic acid

Cetyl alcohol

 

When hydrolysis is carried with caustic alkalies, soap and higher monohydric alcohols are formed.

C15 H31COOC16 H33  + NaOH ® C16 H33 OH + C15 H31COONa

Sodium palmitate (Soap)

The common waxes are:

  • Bees wax, Myricyl palmitate, C15 H31COOC30 H61
  • Spermaceti wax, Cetyl palmitate, C15 H31COOC16 H33
  • Carnauba wax, Myricyl cerotate, C25 H51COOC30 H61

Waxes are used in the manufacture of candles, polishes, inks, water proof coating and cosmetic preparations.

Waxes obtained from plants and animals are different than paraffin wax which is a petroleum product and a mixture of higher hydrocarbons (20 to 30 carbon atoms). So paraffin wax is not an ester.

Candles are prepared by mixing paraffin wax (90%) with higher fatty acids like stearic and palmitic. The fatty acids are added to paraffin wax as to give strength to candles. The mixture is melted and poured into metal tubes containing streched threads. On cooling candles are obtained.

 

The compounds formed by the replacement of one or more hydrogen atoms of the hydrocarbon chain part of the carboxylic acids by atoms or groups such as X (halogen), OH or NH2, are referred to as substituted acids.

 

For example, CH 2ClCOOH

Chloroacetic acid

;    CH 2OHCOOH            ;

Hydroxyacetic acid

CH 2 NH 2COOH

Aminoacetic acid

 

The position of the substituents on the carbon chain are indicated by Greek letters or numbers.

6     5     4     3     2     1

CCCCCC OOH

e     d     g     b     a

 

For example,

CH 3 CHOHCOOH         ;

a -Hydroxypropionic acid 2-Hydroxypropanoic acid

CH 3CHOHCH 2COOH

b -Hydroxybutyric acid 3-Hydroxybutanoic acid

 

Lactic Acid or a-hydroxy propionic acid or 2-hydroxy propanoic acid

It is the main constituent of sour milk. It is manufactured by fermentation of molasses by the micro-organism (Bacterium acidi lactici-sour milk) in presence of CaCO3 .

(1)

3

Method of Preparation

 

From acetaldehyde :

CH 3CHO+ HCN ® CH

CH(OH)CN ¾¾H2O¾H¾+   ® CH

3 CHOHCOOH

 

Acetaldehyde

Cyanohydrin

Lactic acid

 

 

 

(2)  Physical Properties

It is a colourless syrupy liquid having a sour taste and smell.

It is hygroscopic and very soluble in water. It is optically active and exists in three distinct forms.

  • Chemical Properties : It gives reactions of secondary alcoholic group and a carboxylic

 

 

CH3CHOHCOONa

CH CHOCOOH

 

Lactide

Sod. Lactate

3                             3

|

COOH

 

CO+H2O

Heat

NaOH

Acetyl lactic acid

 

Conc. H2SO4

 

 

CH3CHO   +

Acetaldehyde

HCOOH

Formic acid

Dil. H2SO4

Heat 130°C

CH 3CH 2COOH

Propionic acid

 

 

 

CH3CHO

or

CH3COOH

CH 3CHClCOCl

Lactyl chloride

CH3COCOOH

Pyruvic acid

 

  • Uses : It is used in medicine as calcium and iron lactates, as mordant in dyeing, as acidulant in beverages and candies, as a solvent (ethyl and butyl lactates) for cellulose

Tartaric Acid. Or a,a’-Dihydroxy succinic acid or 2,3-Dihydroxy-Butane-1,4-Dioic acid

HO C H COOH

|

HOCHCOOH

It is found as free or potassium salt in grapes, tamarind, and berries.

(1)  Methods of Preparation

  • Argol which separates as a crust during fermentation of grape juice is impure potassium hydrogen tartrate. Argol is boiled with limewater. Calcium tartrate is precipitated which is filtered. The solution contains potassium tartrate which is also precipitated by addition of CaCl2. The calcium salt is then decomposed with calculated quantity of dilute H2SO4. The precipitate (CaSO4) is filtered and the filtrate on concentration gives the crystals of tartaric

 

CH(OH)COOK

2 |

CH(OH)COOH

Pot.hydrogen tartrate

 

  • Ca(OH)2 ®

CH(OH)COOK

|                     +

CH(OH)COOK

Pot.tartrate (Filtrate)

CH(OH)COO

|                         Ca

CH(OH)COO

Calcium tartrate (ppt.)

 

 

 

 

 

CH(OH)COO

|

CH(OH)COO

 

  • Synthetic method

 

Ca + H2SO4 ® CaSO4 +

CaCl2

2KCl

CH(OH)COOH

|

CH(OH)COOH

Tartaric acid

 

 

 

 

CH2CN

 

C + H 2  ¾¾Elec¾t¾ric ® CH  º CH ¾¾H¾2  ® CH 2  = CH 2  ¾¾B¾r2  ® CHBrCHBr ¾¾2KC¾N ® |

 

arc

Acetylene

Pd BaSO4

Ethylene

Ethylene bromide

CH2CN

 

 

 

 

  • CH2COOH

CHBrCOOH

CHOHCOOH

 

¾¾H2O¾H¾®|

¾¾Red¾P ® |

¾¾AgO¾H ®|

 

CH2COOH

Succinic acid

Br2

CHBrCOOH

a ,a ‘-Dibromo succinic

acid

CHOHCOOH

Tartaric acid

 

CHO

CH(OH)CN

  • CH(OH)COOH

 

  • From glyoxal cyanohydrin :

|

CHO

Glyoxal

¾¾HC¾N ®

|

CH(OH)CN

Glyoxal cyanohydrin

¾¾H2O¾H¾® |

CH(OH)COOH

Tartaric acid

 

  • Physical Properties : It is a colourless crystalline compound. It is soluble in water and alcohol but insoluble in ether. It contains two asymmetric carbon atoms and thus shows optical isomerism (four forms). Natural tartaric acid is the dextro It contains two secondary alcoholic groups and two carboxylic groups.

Optical Isomerism in tartaric acid

 

 

COOH

|

HCOH

|

COOH

|

HOCH

|

HCO        H

COOH

|

HCOH

|

 

 

 

 

d+ Dextrorotatory Tartaric acid

l-(Leavorotatory acid)                                         Meso-Tartaric acid (Optical inactive)

Optical active

 

  • d + Tartaric acid-Dextro-rotatory
  • l –Tartaric acid-Leavorotatory      

 

Optical active

 

  • Meso tartaric acid-optically inactive due to internal
  • Racemic tartaric acid (Equimolar mixture of d+, l–forms). Optically inactive due to external compensation

(3)  Chemical Properties

 

 

CHCOOH

||

CCOOH

|

CH2COOH

Aconitic acid Heat, 150°C

With alkalies and alcohols, it forms three series of salts and esters, respectively

 

 

 

 

CH3COCl

HCl

CH 2COOH

|

C(OCOCH3)COOH

|

CH2COOH

Mono acelyderivative

 

 

 

 

CH2COOH

CH COOH

 

|                                                       | 2

 

CO

|

CH2COOH

Acetone diartboxylic acid

CHCOOH

|

CH2COOH

Tricarballytic acid

 

 

 

  • Uses : It is used in carbonated beverages and effervescent tablets, in making baking powder (cream of tartar) and mordant in dyeing (potassium hydrogen tartrate), in preparing Fehling’s solution (sodium potassium tartrate–Rochelle salt), in medicine as emetic, dyeing and calico-printing (tartar emetic-potassium antimonyl tartrate) and silver

 

(5)  Tests

  • When heated strongly, tartaric acid chars readily giving a smell of burnt sugar to produce free carbon and pyruvic
  • With AgNO3 : A neutral solution of tartaric acid gives a white which is soluble in ammonia. A silver mirror is obtained on warming the ammonical silver nitrate solution (Tollen’s reagent).
  • With Fenton’s reagent : (H2O2 containing a little of ferrous salt) and caustic soda, It gives a violet
  • With Resorcinol and H2SO4 : It gives blue colour.

Citric Acid Or 2-Hydroxypropane Or 1,2,3-Tri Carboxylic Acid Or b-Hydroxy Tricarballylic Acid

It occurs in the juice of citrus fruits such as lemon, galgal, orange, lime, etc. Lemon juice contains 6-10% of citric acid.

(1)  Methods of Preparation

  • By Fermentation : Citric acid is obtained by carrying fermentation of dilute solution of molasses with

 

micro-organism, Aspergillus nigar, at 26-28°C for 7 to 10 days. The resulting solution is neutralised with

Ca(OH)2

 

to form insoluble precipitate, calcium citrate. It is decomposed by dilute solution is concentrated under vacuum to get crystals of citric acid.

HSO4 . The

CaSO4 is filtered off and the

 

  • By Lemon juice : It is also obtained from lemon The juice is boiled to coagulate proteins. From clear solution, citric acid is obtained as calcium salt with Ca(OH)2 as described in the above method.
  • By synthetic method :

 

CH2OH

CH2Cl

CH2Cl

CH2Cl

CH2CN

CH2COOH

 

|                    HCl(g)        |

dil. HNO             |

|

HCN

OH       KCN             |

OH       H  O  H +             |

 

C HOH  ¾¾ ¾® CHOH ¾¾¾¾3  ® CO

¾¾¾® C

¾¾¾® C

¾¾2 ¾¾® C(OH)COOH

 

|                      heat       |

[O]            |

|           CN

|           CN                            |

 

CH2OH  (in acetic acid)   CH2Cl

Glycerol

CH2Cl

CH2Cl

CH2CN

CH2COOH

 

  • Physical Properties : It is a colourless crystalline compound. It possesses one water molecule as water of It is soluble in water and alcohol but less soluble in ether. It is not optically active compound. It is nontoxic in nature. It behaves as an alcohol and tribasic acid.

 

 

 

 

(3)  Chemical Properties

 

Pot. acid tartrate

CHOHCOOK

|

CHOHCOOH

 

 

and

 

Potassium tartrate

CHOHCOOK

|

CHOHCOOK

 

 

C(OH)COOH

||

 

CH 3COCOOH

Pyruvic acid

It forms two series of salts

 

Heat

[O] Fe 2+ /H2O2

C(OH)COOH

Dihydroxy meleic acid

 

 

CHBrCOOH

|

 

HBr

Fenton’ s reagent

 

AgNO3            Tartronic acid + Sliver mirror

 

CHBrCOOH

a,aDibromo succinic acid

NH4OH

(Test of tartaric acid)

 

CH(OH)COOH

 

COOH

 

HI         Heat

|                        ¾¾¾[O¾]  ¾®     |

 

 

CH2COOH

CHOHCOOH

HI

COOH

K2Cr2O7/H2SO4

COOH

Oxalic acid

 

|                 ¬¾¾ |

CH(OH)COOH

COOH

 

CH2COOH

Sucinic acid

Heat

CH2COOH

Malic acid

Complex formation

|

COOH

Tartronic acid

¾¾[¾O] ®

|

COOH

Oxalic acid

 

NaOOCCH O

|

NaOOCCHO

O HC COONa

|

O HC COONa

 

  • Uses : It finds use in making lemonades, as acidulant in food and soft drinks and makes the lemon sour, as mordant in dyeing and calico printing. Ferric ammonium citrate, magnesium citrate (as an antacid and laxative), sodium or potassium citrate are used in Ferric ammonium citrate finds use in making blue prints.

Aromatic acid contain one or more carboxyl group (COOH) attached directly to aromatic nucleus.

Examples

 

COOH

 

 

Benzoic acid

COOH

CH3

 

O-toluic acid

 

COOH COOH

Phthalic acid

 

COOH OH

Salicylic acid

 

COOH NH2

Anthranilic acid

COOH

 

NO2

m-Nitro benzoic acid

 

Aromatic acid containing-COOH group in the side chain, they are considered as aryl substituted aliphatic acid.

 

Examples

CH2COOH

CH = CHCOOH

 

 

 

 

Phenyl acetic acid                                               Cinnamic acid

The IUPAC names of the substituted acids are derived by prefixing the name of the substituent to the name of parent acid i.e., benzoic acid and the position is indicated by an arabic numeral with the carbon atom carrying the

COOH group being numbered as 1. For example,

 

COOH

 

 

Benzoic acid

COOH

CH3

 

2-Methylbenzoic acid (o-Toluic acid)

COOH

OH

 

  • Hydroxybenzoic acid (o-salicylic acid)

COOH

 

NO2

  • Nitrobenzoic acid

 

 

 

 

COOH

COOH

COOH

 

 

 

 

 

 

Br

  • Bromobenzoic acid

 

NH2

4-Aminobenzoic acid

OCH3

4-Methoxy benzoic acid (p-Anisic acid)

 

Benzoic Acid

 

(1)  Methods of Preparation

  • From oxidation of Benzyl alcohol [Laboratory method]

 

CH2OH

 

O

 

Benzyl alcohol

CHO

O

 

Benzaldehyde

COOH

 

 

 

Benzoic acid

 

 

 

  • From hydrolysis of nitriles or cyanides

CN

 

COOH

 

 

 

+ 2H2O

H+ or OH

+ 2NH3

 

 

 

Benzonitrile

 

  • From Grignard reagent

Benzoic acid

 

 

O

||

 

MgI

O

||

+ C = O

C – OMgI

 

H+ , H2O

COOH

+ Mg        OH I

 

Phenyl mag. iodide

 

  • By hydrolysis of esters

Addition product

Benzoic acid

 

C6 H5 COOCH3

  • H 2

O ¾¾Ho¾rOH¾–  ® C  H  COOH+ CH

6

5

3OH

 

Methyl benzoate

Benzoic acid

Methanol

 

  • From trihalogen derivatives of hydrocarbons

 

CCl3

C(OH)3

COOH

 

 

+ 3KOH – 3 KCl                                                                                              +  H2O

 

 

Benzotrichloride

Unstable

Benzoic acid

 

 

 

  • From benzene

COCl                            COOH

 

 

 

 

  • From Toluene

COCl2

AlCl3

H2 O/NaOH

[Friedel-craft reaction]

 

H3C                                           COOH

 

 

[O], D

KMnO4/OH

or alkaline K2Cr2O7

 

Note : ® Chromic trioxide in glacial acetic acid or Co-Mn acetate can also be taken in place of alkaline

  • From o-xylene [Industrial method]

 

 

KMnO4 .

 

 

 

CH3

[O]                              CO

V O                                                                  O

COOH

COOH

 

2    5

CH3                                                 CO

COOH

 

 

 

  • From naphthalene [Industrial method]

COOH

COOH

COOH

 

(2)  Physical Properties

  • It is a white crystalline
  • It has p. 394 K.
  • It is sparingly soluble in cold water but fairly soluble in hot water, alcohol and
  • It has a faint aromatic odour and readily sublimes and is volatile in
  • Acidity of Aromatic Carboxylic Acid : Aromatic acid dissociates to give a carboxylate anion and proton.

 

C6 H5 COOH

+

C6 H5 COO + H

 

Since the carboxylate anion (ArCOOH).

(ArCO O)

is resonance stabilised to a greater extent than the carboxylic acid

 

O                              O

||                               |        +

O                             O

||                               |

 

Ar COH « Ar C = O H                       Ar CO « Ar C  = O

 

Resonance in carboxylic acid

éNon – equivalent structure andù

Resonance in carboxylate anion

éEquivalent structure and henceù

 

ë
ë
û
û

êhence less stable                      ú          êmore stable                              ú

Effect of Substituents on Acidity : The overall influence of a substituent on acidity of substituted benzoic acids is due to two factors.

  • Inductive effect : If the substituent exerts–I effect, it increases the acidity of carboxylic acids, while if it exerts + I effect it decreases the Inductive effect affects all positions, i.e., o–, m– and p–.

 

 

 

  • Resonance effect : Like inductive effect, if the resonance producing group exerts minus effect e., if it withdraws electrons, it increases the strength of the benzoic acid. Similarly, if the group causes +R effect it decreases the acidity of benzoic acid. However, remember that resonance effect affects only o- and p- positions. Thus if resonance producing group is present in the m-position it will not exert its effect.

In case resonance and inductive effects both operate in the molecule, resonance effect being stronger overpowers the inductive effect.

Thus on the above basis, the following order of acidity can be explained.

NO2                        Cl                                                                                    OH

 

 

 

COOH

p-Nitrobenzoic acid

NO2 group exerts

R and – I effects

COOH

p-Chlorobenzoic acid

Cl group exerts

I effects, + R

COOH

Benzoic acid No other group

COOH

p-Hydroxybenzoic acid

OH group exerts

+ R and – I effects

 

Similarly :

NO2                                     NO2

COOH

NO2

COOH

 

 

 

COOH

COOH

 

Acidity is only due to electron withdrawing inductive effect of the – NO2 group (resonance does not affect the m-position) while in the p-isomer acidity is due to electron withdrawing inductive as well as resonance effect.

The acidity of the three isomers of hydroxybenzoic acids follows the following order.

 

OH                                      OH

COOH

COOH                        OH

 

 

 

 

I effect

+ M effect

COOH

COOH

 

Resonance effect cannot operate and hence only the acid-strengthening –I effect takes part with the result

m-hydroxybenzoic acid is stronger acid than benzoic acid. Like other substituted benzoic acid.

Acidic character among benzoic acids having different electron releasing group.

 

COOH                            COOH

COOH

COOH

 

 

 

> 

 

OCH3

> CH3COOH >

 

OH

 

NH2

>

 

CH3

 

(4)  Chemical Properties :

  • Reactions of carboxylic group (ii) Reactions of aromatic ring
  • Reactions of Carboxylic Group
  • Reaction with metals

 

 

 

 

COOH

+2 Na

COONa

 

+ H2

 

 

 

  • Reaction with Alkalies Or NaHCO3 Or Na2CO3 :

COOH

+ NaOH

or NaHCO3 or Na2CO3

COONa

 

+ H2O

 

  • Formation of Esters :

Aromatic acid (benzoic acid) having no group in its ortho positions can be readily esterified with alcohol in

 

presence of a mineral acid.

COOH

+

+ C H OH           H

COOC2H5 + H2O

 

2     5

 

In presence of ortho substituent the rate of esterification is greatly decreased due to steric effect. The esterification of the various benzoic acids :

 

COOH

COOH

CH3

CH2COOH

H3C                     CH3

;

 

 

 

Benzoic acid

2-Methylbenzoic acid

2, 6-Dimethylbenzoic acid

2,6-Dimethyl phenylacetic acid

 

The substituted phenylacetic acid is easily esterified because – COOH group is separated from benzene ring by – CH2 – part.

The ortho-substituted benzoic acids can be easily esterified by treating the silver salt of the acid with alkyl

 

halides, i.e.,

COOC2H5

 

 

 

AgNO3

C2H5Br

 

 

 

This is due to the fact that in such cases the attack of the alkyl moiety of the alkyl halides is on the oxygen atom of the – COOH group but not on the sterically hindered carbon atom.

  • Formation of acid chloride

 

COOH

COCl

 

+ PCl5 or SOCl2                          + POCl3 + HCl

 

 

 

  • Reaction with N3H [Schmidt reaction]

COOH

+ N3H

 

 

 

H2SO4

50° C

Benzoyl Chloride

 

NH2

+ CO2

Aniline

 

 

+ N2

 

 

 

 

  • Reaction with sodalime

 

COOH

NaOH + CaO

 

 

+ CO2

 

 

 

 

  • Reaction with anhydride

Benzene

 

O              O

||              ||

 

COOH

+ (CH3CO)2 O         D

C – O – C

 

 

 

 

  • Reduction

 

 

 

  • Decarboxylation

COOH

+ LiAlH4

Benzoic anhydride

 

CH2OH

+ H2O

Benzyl alcohol

 

COOH                                                    CHO

 

+ HCOOH

MnO

D

+CO2

+ H2O

 

 

 

  • Hunsdiecker reaction : C6 H5 COOAg
  • X 2

¾¾in C¾C¾l4  ® CH5  – X + CO2  ­ + AgX

 

Silver benzoate

 

  • Reactions of Aromatic Ring
  • Nitration

(Br2 or Cl2 )

heat

Phenyl halide

 

COOH                                          COOH

 

 

 

 

 

 

  • Sulphonation

 

COOH

+ HNO3

H2SO4

 

NO2

m-nitrobenzoic acid

 

 

 

COOH

 

 

 

 

 

 

 

  • Chlorination

+ Fuming H2SO4

 

SO3H

m-sulpho benzoic acid

 

 

 

COOH

 

+ Cl2

 

 

Fecl3

COOH

 

 

 

Cl

m-chloro benzoic acid

 

 

 

 

  • Reduction

 

COOH

 

COOH

 

 

 

Na/amyl alcohol Boil, 3H2

 

 

  • Uses : Benzoic acid is used,

 

 

Cyclo hexanoic acid

 

  • in medicine in the form of its salts especially as urinary
  • As sodium benzoate for preservation of food such as fruit juices, tomato ketchup, pickles
  • In the preparation of aniline
  • In treatment of skin diseases like

(6)  General Tests

  • Benzoic acid dissolves in hot water but separates out in the form of white shining flakes on
  • It evolves CO2 with sodium bicarbonate, e., it gives effervescence with sodium carbonate.
  • Neutral ferric chloride gives a buff coloured
  • When warmed with ethyl alcohol and a little H2SO4, a fragrant odour of ethyl benzoate is obtained.
  • When heated strongly with soda lime, benzene vapours are evolved which are

 

Cinnamic Acid [b-Phenyl acrylic acid]

 

 

CH = CH – COOH

 

(1)  Methods of Preparation

 

 

 

  • By Perkin’s reaction

CH5CHO + (CH3CO)2 O ¾¾CH¾3CO¾ON¾a ® CH5CH = CHCOOH + CH3COOH

180°C

 

  • By Claisen condensation

CHCHO + CHCOOCH 5  ¾¾CH¾5 O¾N¾a ® CHCH = CHCOOCH 5  ¾¾HO ®

 

 

 

  • By knoevenagel reaction

Ester

H +

 

C6 H 5 CH = CHCOOH + C2 H 5 OH

 

 

CHCHO + CH 2 (COOH)2  ¾¾NH¾3  ® CHCH  = CHCOOH + CO2  + HO

heat

 

  • Industrial method

 

CH5CHCl2 + H2CHCOONa ¾¾200¾°¾C ® CH5CH  = CHCOOH + NaCl + HCl

Benzal chloride                 Sodium acetate

(2)  Physical Properties

  • It is a white crystalline solid and its melting point 133°C.

 

 

 

 

  • It is very sparingly soluble in
  • It exhibits geometrical

C6 H5 – CH

||

H C COOH

Trans-form (Cinnamic acid)

 

 

C6 H5 – CH

||

HOOCCH

Cis-form (Allo cinnamic acid)

 

 

Cinnamic acid (stable form) occurs in nature both free and as esters in balsams and resins.

 

 

  • Chemical Properties : It also gives reactions of benzene

 

Oxidation   C H CHO + C H COOH

CrO3                                         6  5                    6  5

 

Benzaldehyde

Benzoic acid

 

 

Reduction

Na(Hg)/H2O

C6H5CH2CH2COOH

 

 

 

Reduction

LiAlH4

b-Phenyl propionic acid

 

C6H5CH2CH2CH2OH

 

 

 

 

CH = CH – COOH

10°C

 

 

 

Soda lime

distilled

3-Phenyl propyl alcohol

C6H5CH = CHCH2OH

Cinnamyl alcohol

 

C6H5CH = CH2

Styrene

 

 

 

Br2

C6H5CHBrCHBrCOOH

Dibromocinnamic acid

 

 

 

 

 

Nitration Conc. HNO3/H2SO4

CH = CHCOOH NO2

+

CH = CHCOOH

 

 

 

 

PCl5

o-Nitrocinnamic acid

NO2

p-Nitrocinnamic acid

 

C6H5CH = CHCOCl

Cinnamyl chloride

 

 

C2H5OH H+

 

C6H5CH = CHCOOC2H5

Ethyl cinnamate

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