Chemical Properties of Aromatic Compounds

Q.

Why does benzene undergo electrophilic substitution reactions easily and nucleophilic substitutions with difficulty?

Q. An organic compound (A) with molecular formula $C_8{H}_{8}O$ forms an orange-red precipitate with $2,4-\text{DNP}$ reagent and gives yellow precipitate on heating with iodine in the presence of sodium hydroxide. It neither reduces Tollens' or Fehling's reagent, nor does it decolourise bromine water or Baeyer's reagent. On drastic oxidation with chromic acid, it gives a carboxylic acid (B) having molecular formula $C_7{H}_6{O}_2$. Identify the compounds (A) and (B) and explain the reactions involved.

Q. Which of the following structural isomers of compound $C_4{H}_{9}Br$ is most reactive towards $S_{N}1$ reaction ?

1. 
2. 
3. 
4. 

Q. Most common reactions of benzene (aromatic hydrocarbon) and its derivatives are

1. Electrophilic addition reactions
2. Electrophilic substitution reactions
3. Nucleophilic addition reactions
4. Nucleophilic substitution reactions

Q. Arrange in order of decreasing trend towards electrophilic substitution reactions: Chlorobenzene (I), Benzene (II), toluene (III) anilinium chloride (IV)

1. III> II > I > IV
2. II > I > IV > III
3. I > II > IV > III
4. IV > I > II > III

Q. Is NH2 more electron Donating than CH2^-(minus)??

Q. Which of the compound undergoes electrophilic substition most easily?

1. 
2. 
3. 
4. 

Q. cis-1-chloro-2 methyl cyclohexane is subjected to dehydrohalogenation by E2 mechanism. The product is

1. 3-methylcyclohexene
2. 1-methylcyclohexene
3. Methylidene cyclohexene
4. 6-methylcyclohexene

Q. The reaction of $SOC{l}_2$ on alcohols to form alkyl chlorides gives good yields because

1. alkyl chlorides are immiscible with $SOC{l}_2$
2. by-products of the reaction are gaseous and escape out
3. alcohol and $SOC{l}_2$ are soluble in water
4. the reaction does not occur via intermediate formation of an alkyl chlorosulphite

Q. Consider the following reaction, How many different monobromo derivatives would be produced?

1. 2
2. 4
3. \N
4. 1

Q. What is an acylium ion?

1. Carbocation formed from acyl chloride
2. A carbon with a double bond to an oxygen and a single bond to a halogen
3. A carbon-oxygen double bond
4. An aluminum chloride acid

Q. For the given reaction, what is A?

1. 
2. 
3. 

4. $C{H}_{3}C{H}_{2}C{H}_{2}N{H}_2$

Q. Arrange the following in the order of reactivity towards an electrophilic attack

1. V > IV > III > II > I
2. III > V > IV > II > I
3. III > IV > V > II > I
4. V > IV > III > I > II

Q. 59. Why phenol is more reactive than anisole ?

Q. The most common type of reaction in aromatic compounds is :

1. Elimination reaction.
2. Addition reaction.
3. Electrophilic substitution reaction
4. Rearrangement reaction

Q. In coupling reactions, diazonium ion acts as:

1. Nucleophile
2. Electrophile
3. Solvent
4. None of the above

Q. Bromination of toluene gives

1. Only p-substituted product
2. Mixture of o- and p-substituted product
3. Mixture of o- and m-substituted product
4. Only m-substituted product

Q. Reactivity order of CH3CHO, C2H5COCH3 and CH3COCH3 with HCN

Q. 38. Ptcl2.2h2o does not react with AgNO3

Q. The major product of the given reaction is:

1. Hexachlorocyclohexane
2. Hexachlorobenzene
3. Cyclohexane
4. Chlorobenzene

Q. Arrange the following in the order of reactivity towards an electrophilic attack

1. V > IV > III > II > I
2. III > V > IV > II > I
3. III > IV > V > II > I
4. V > IV > III > I > II

Q.

For M²⁺/M and M³⁺/M²⁺ systems, the values for some metals are as follows:

Cr²⁺/Cr −0.9V

Cr³/Cr²⁺ −0.4 V

Mn²⁺/Mn −1.2V

Mn³⁺ /Mn²⁺ +1.5 V

Fe²⁺ /Fe −0.4V

Fe³⁺/Fe²⁺ +0.8 V

Use this data to comment upon:

(i) The stability of Fe³⁺ in acid solution as compared to that of Cr³⁺ or Mn³⁺ and

(ii) The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.

Q. The total number of structural isomers formed in the following reaction is:

1. $6$
2. $5$
3. $4$
4. $3$

Q. n – Propyl chloride and benzene react in the presence of anhydrous $AlC{l}_3$ to form

1. ethyl benzene
2. methyl benzene
3. n – propyl benzene
4. iso – propyl benzene

Q.

When benzene is treated with excess of $C{l}_2$ in the presence of hν or light, the end product is

1. Monochlorobenzene

2. Trichlorobenzene

3. Hexachlorobenzene

4. Benzene hexachloride

Q. Predict the major organic product for given Friedel-Crafts alkylation reaction:

1. 
2. 
3. 
4. 

Q. Complete the reaction

1. $A\to$ Benzene sulphonic acid $B\to$ Benzenesulphonic acid
2. $A\to$ Nitrobenzene $B\to$ m-bromonitrobenzene
3. $A\to$ Nitrobenzene $B\to$Trinitrobenzene
4. $A\to$ Nitrobenzene $B\to$ p-bromonitrobenzene

Q.

Name the following:

A gas used for the artificial ripening of fruits.

Q. Select incorrect reaction(s) / statement(s):

1. 
2. Meta formaldehyde is trimer of formaldehyde while para aldehyde is tetramer of acetaldehyde.
3. 
4. 

Q. The most common type of reaction in aromatic compounds is :

1. Elimination reaction.
2. Addition reaction.
3. Electrophilic substitution reaction
4. Rearrangement reaction