Problem 8 - Chemistry An Atoms First Approach

Question

Give an example reaction that would yield the following products. Name the organic reactant and product in each reaction. a. alkane b. monohalogenated alkane c. dihalogenated alkane d. tetrahalogenated alkane e. monohalogenated benzene f. alkene

Step-by-Step Solution

Answer

a. Alkane: Ethene (C2H4) + Hydrogen (H2) -> Ethane (C2H6) b. Monohalogenated alkane: Methane (CH4) + Chlorine (Cl2) -> Chloromethane (CH3Cl) + HCl c. Dihalogenated alkane: Chloromethane (CH3Cl) + Chlorine (Cl2) -> Dichloromethane (CH2Cl2) + HCl d. Tetrahalogenated alkane: Trichloromethane (CHCl3) + Chlorine (Cl2) -> Tetrachloromethane (CCl4) + HCl e. Monohalogenated benzene: Benzene (C6H6) + Chlorine (Cl2) -> Chlorobenzene (C6H5Cl) + HCl f. Alkene: Ethanol (C2H5OH) + Sulfuric Acid (H2SO4) -> Ethene (C2H4) + H2O

Step 1: a. Alkane

An example of a reaction that yields an alkane is the hydrogenation of an alkene. In this reaction, an alkene reacts with hydrogen gas in the presence of a catalyst, such as platinum or palladium. For example, ethene (C2H4) reacts with hydrogen (H2) to form ethane (C2H6): \[ \mathrm{C_2H_4 + H_2 \xrightarrow[Pd\ or\ Pt]{\ 300^{\circ}C} C_2H_6} \]

Step 2: b. Monohalogenated alkane

An example of a reaction that yields a monohalogenated alkane is the halogenation of an alkane. In this reaction, an alkane reacts with a halogen in the presence of ultraviolet (UV) light. For example, methane (CH4) reacts with chlorine (Cl2) to form chloromethane (CH3Cl): \[ \mathrm{CH_4 + Cl_2 \xrightarrow[]{\ hs\nu} CH_3Cl + HCl} \]

Step 3: c. Dihalogenated alkane

An example of a reaction that yields a dihalogenated alkane is the further halogenation of a monohalogenated alkane. In this reaction, a monohalogenated alkane reacts with a halogen in the presence of ultraviolet (UV) light. For example, chloromethane (CH3Cl) reacts with chlorine (Cl2) to form dichloromethane (CH2Cl2): \[ \mathrm{CH_3Cl + Cl_2 \xrightarrow[]{\ hs\nu} CH_2Cl_2 + HCl} \]

Step 4: d. Tetrahalogenated alkane

An example of a reaction that yields a tetrahalogenated alkane is the halogenation of a trihalogenated alkane. Here, a trihalogenated alkane reacts with a halogen in the presence of ultraviolet (UV) light. For example, trichloromethane (CHCl3) reacts with chlorine (Cl2) to form tetrachloromethane (CCl4): \[ \mathrm{CHCl_3 + Cl_2 \xrightarrow[]{\ hs\nu} CCl_4 + HCl} \]

Step 5: e. Monohalogenated benzene

An example of a reaction that yields a monohalogenated benzene is the halogenation of benzene. In this reaction, benzene (C6H6) reacts with a halogen in the presence of a halogen carrier, such as aluminum chloride (AlCl3) in case of chlorination. For example, benzene reacts with chlorine (Cl2) in the presence of a halogen carrier to form chlorobenzene (C6H5Cl): \[ \mathrm{C_6H_6 + Cl_2 \xrightarrow[]{\ AlCl_3} C_6H_5Cl + HCl} \]

Step 6: f. Alkene

An example of a reaction that yields an alkene is the dehydration of an alcohol. In this reaction, an alcohol reacts with a strong acid, such as sulfuric acid (H2SO4), to form the corresponding alkene. For example, ethanol (C2H5OH) reacts with sulfuric acid (H2SO4) to form ethene (C2H4): \[ \mathrm{C_2H_5OH \xrightarrow[]{\ H_2SO_4} C_2H_4 + H_2O} \]