Question

1) Predict the product of the reaction of 1-butene with bromine (The IUPAC name)

2) An alkyne undergoes hydrogenation to produce an alkene as follows: RC(triple bond)CR +H2 (Pd catalyst) alkene predict the product.

3) Predict the ester product of the following reaction: CH3OH + CH3CH2CH2COOH (H2SO4) PRODUCT + H20 (Express your answer using the IUPAC name)

4) Predict the carboxylic acid product of the following reaction: CH3COOCH2CH3 + H20 (H+) carbxylic acid + CH3CH2OH (Express your answer using the IUPAC name

Answer 1

Concepts and reason

The concept used to solve this question is to predict the products of the given reaction and to write the IUPAC name of the products. The first reaction is the addition reaction of alkene with bromine which yields dibromo product. The second reaction is the hydrogenation of alkyne with ${{\rm{H}}_{\rm{2}}}$ gas in presence of Pd catalyst which yields alkane as product. The third reaction is the esterification reaction of carboxylic acid with an alcohol which yields corresponding ester of carboxylic acid. The IUPAC names of the products can be written by using IUPAC rules into consideration.

Fundamentals

1) The hydrocarbons with at least one double bond are known as alkenes. Alkenes involve in addition reactions because of $\pi$ -bond electrons. Alkene on reaction with bromine molecule yields dibromo product. In this reaction, the bromine molecule added across the double bond to give 1,2-dibromoprodcut.

2) The hydrocarbons with at least one triple bond are known as alkynes. The alkynes undergo hydrogenation reaction on reaction with hydrogen gas in presence of palladium catalyst to give saturated hydrocarbons, alkanes.

3) The carboxylic acids are organic compound with carboxylic acid functional group (-COOH) and alcohols are the organic compounds with alcohol functional group (-OH). When carboxylic acid reacts with an alcohol in presence of acid undergoes esterification reaction to give corresponding ester of carboxylic acid as product. In this reaction, water molecule is eliminated during the esterification.

IUPAC Nomenclature: There are some fundamental rules to assign the name of the compounds. They are as follows:

1. Identify and name the longest chain (parent chain) in the compound (whether a continuous chain or a ring).

2. Find and name the functional groups and side chains attached to this chain.

3. Identify the multiple bonds (double/triple bonds)

4. Number the chain, in such way that the substituents get the lowest possible number.

5. Assign the location of each substituent by a suitable number and name.

6. If there are more than one type of functional groups present the prefixes di, tri, tetra, etc are used which are not considered when alphabetizing.

7. Assemble the name and groups in alphabetical order by using full name.

1)

The given starting material is 1-butene and the structure of 1-butene is shown below.

From the structure, it is clear that it has one double bond and it is an alkene.

According to discussion in fundamental section, alkene on reaction with bromine molecule yields dibromo product.

Thus, 1-butene on reaction with bromine molecule yields 1,2-dibromo product. The structure of the product is shown below in the reaction.

In the structure of the product, the longest chain has 4 carbons, so the parent carbon chain is butane. Now, number the chain in such a way that the substituents get the lowest possible number. Thus, two bromo substituents get 1^st and 2^nd positions. Now assemble the name and substituents in alphabetical order by using parent name. Therefore, the IUPAC name of the product is 1,2-dibromobutane.

2)

The given starting material is an alkyne and the structure of alkyne is shown below.

From the structure, it is clear that it has one triple bond.

According to discussion in fundamental section, alkynes undergo hydrogenation reaction on reaction with hydrogen in presence of palladium catalyst to give alkanes.

Thus, the given alkyne on reaction with hydrogen gas in the presence Pd catalyst undergoes hydrogenation to give alkane as product. In this reaction, two moles of hydrogen gas is involved. The structure of the product is shown below in the reaction.

3)

The condensed formulas of the given starting materials are as follows:

In the above two compounds, the first one is alcohol and the second one is carboxylic acid.

According to discussion in fundamental section, when carboxylic acid reacts with an alcohol in presence of acid undergoes esterification reaction to give corresponding ester of carboxylic acid as product.

Thus, butanoic acid reacts with methanol in presence of sulfuric acid gives methyl ester as product by the removal of water molecule. The structure of the product is shown below in the reaction.

In the structure of the product, the longest chain has 4 carbons, so the parent carbon chain is butane. The functional group present in the product is ester and it is methyl ester. Thus, ‘e’ of the parent hydrocarbon is replaced with the suffix ‘oate’. Therefore, the IUPAC name of the product is methyl butanoate.

Ans: Part 1

The product formed by the reaction of 1-butene with bromine is 1,2-bromobutane and the structure of the product is shown below.

Part 2

The product formed by the reaction of alkyne with hydrogen gas in the presence of palladium catalyst is alkane and the structure of the product is shown below.

Part 3

The structure of ester product formed by the reaction of given carboxylic acid with alcohol is shown below.

${\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{C}}{{\rm{H}}_{\rm{2}}}{\rm{C}}{{\rm{H}}_{\rm{2}}}{\rm{COOC}}{{\rm{H}}_{\rm{3}}}$