For tasks 13-15, use the substances whose structural formulas are given in the list: 1) H₂C=CH-CH₃ 2) H₃C-CH₂-C(=O)H 3) H₃C-CH₂-CH₂-OH 4) 5) From the list provided, select the substances that correspond to the indicated classes/groups of organic compounds. Write the structural formulas of the corresponding substances in the table. Cycloalkane Aldehyde Fill in the structural formulas of the missing substances in the given chemical reaction schemes, choosing them from the list above. Balance the coefficients in the resulting schemes to obtain chemical reaction equations. 1) 2) + H₂ + Br₂ + H₂O → H₃C-CH₂-C(=O)-OH + HBr

Task 13: Classification of Organic Compounds

Let's analyze the given organic compounds and classify them:

• 1) H₂C=CH-CH₃ - This is propene, an alkene (contains a carbon-carbon double bond).
• 2) H₃C-CH₂-C(=O)H - This is propanal, an aldehyde (contains a carbonyl group bonded to a hydrogen atom and an alkyl group).
• 3) H₃C-CH₂-CH₂-OH - This is propanol, an alcohol (contains a hydroxyl group bonded to an alkyl group).
• 4) Cyclohexane - This is a cycloalkane (a cyclic alkane).
• 5) Toluene - This is an arene (an aromatic hydrocarbon).

Now, let's fill the table:

Task 14: Balancing Chemical Reactions

Let's complete and balance the given chemical reactions:

1) Reaction to form Toluene (Arene) and Hydrogen

The product is toluene (an arene), and hydrogen gas (H₂) is also a product. Toluene has the formula C₆H₅CH₃. This reaction is likely the hydrogenation of an unsaturated cyclic compound or a similar process.

Given the options, and the product being toluene, a likely reactant that would form toluene and hydrogen upon reaction is benzene with an alkylating agent (like CH₃Cl in the presence of a Lewis acid), or more relevantly here, a cyclization and dehydrogenation process. However, if we consider the reverse reaction (hydrogenation of toluene), it would require high pressure and temperature and a catalyst, and it would form methylcyclohexane, not just benzene and H₂.

Let's re-examine the reactants and products. The product is shown as toluene (C₆H₅CH₃) and H₂. A plausible reaction forming this from the given list would be the dehydrogenation of methylcyclohexane. However, methylcyclohexane is not in the list. If we consider the Friedel-Crafts alkylation, it would typically be benzene + CH₃Cl -> Toluene + HCl. This does not fit.

Let's assume the reaction is intended to be the formation of Toluene from something that yields H₂. A common reaction is the catalytic reforming of alkanes, but we don't have simple alkanes that directly yield toluene and H₂ in one step from the list.

Let's consider another possibility. The image shows: ... → [Benzene ring with CH₃ attached] + H₂

If we assume the reactant is methylcyclohexane (which is not listed, but structurally similar to option 4), then the reaction would be:

Methylcyclohexane → Toluene + 3H₂. This doesn't fit the provided list.

Let's reconsider the provided list of compounds. Option 4 is cyclohexane. Option 5 is toluene. The reaction shows an arrow pointing to toluene and H₂. This implies toluene is a product. If we assume the reaction is catalytic reforming or dehydrogenation, it would typically start with a cyclic alkane or an acyclic alkane. Cyclohexane (4) can be dehydrogenated to benzene, not toluene.

Let's assume there's a typo or a misunderstanding of the question's intent related to the provided options. If we were to form toluene and H₂, a common industrial process is catalytic reforming, which starts with naphtha (a mixture of hydrocarbons). Alternatively, if we consider the synthesis of benzene from acetylene (which is not listed), then further alkylation would be needed.

Given the options, and the fact that toluene is *an* arene and H₂ is produced, and option 5 is toluene, it is most likely that the reaction intends to show the formation of toluene. However, none of the provided reactants (1-4) directly and simply form toluene and H₂ in a balanced equation as shown.

Let's make an educated guess based on common organic reactions taught at this level. If we consider the possibility of a synthesis starting from a simpler molecule and building up, it's complex.

Let's assume the question is asking to identify a reaction where toluene is formed. If we consider the reverse of hydrogenation, dehydrogenation: Methylcyclohexane $$\xrightarrow{\text{catalyst}}$$ Toluene + 3H₂. Methylcyclohexane is not in the list.

What if the reactant is something that leads to the benzene ring formation and attachment of a methyl group? This is becoming overly complex for a simple fill-in-the-blank.

Let's consider if any of the reactants could lead to toluene. Option 1 (propene) and Option 4 (cyclohexane) are the most likely starting points for transformations related to ring structures or C-C bond formations.

If we assume the reaction is the synthesis of toluene, and H₂ is a byproduct, then a possible precursor *not* in the list could be methylcyclohexane. However, we must use the provided list.

Let's assume the question is flawed or relies on external knowledge. If we were forced to pick a reactant from the list that could, under some conditions (perhaps not explicitly shown), lead to toluene and H₂, it's difficult.

Revisiting the image carefully: The arrow points *to* the toluene and H₂. This means the blank space is the reactant. The reaction shown is: [Reactant] → Toluene + H₂.

Consider the dehydrogenation of methylcyclohexane: Methylcyclohexane $$\xrightarrow{\text{catalyst}}$$ Toluene + 3H₂. If the reactant were methylcyclohexane (a cycloalkane derivative), this would fit. Option 4 is cyclohexane. Dehydrogenation of cyclohexane yields benzene + 3H₂. That's not toluene.

What if the reaction is a complex pathway? For example, cyclization of an acyclic precursor. None of the simple alkenes or alcohols would directly form toluene.

Let's consider the possibility that the question is asking for a reaction *involving* toluene. But the arrow indicates it's a product.

Let's assume a common named reaction is implied. Perhaps it's related to aromaticity.

Possible interpretation: If we consider the synthesis of aromatic rings, like the cyclotrimerization of alkynes (e.g., 3 moles of acetylene form benzene), then alkylation would be needed.

Most plausible, though still problematic, interpretation: If we assume the question implies a process where toluene is formed and H₂ is a byproduct, and we must pick a reactant that could *ultimately* lead to this, it's still unclear from the list.

Let's search for common reactions producing toluene and H₂. Catalytic dehydrogenation of methylcyclohexane is the most direct. Since methylcyclohexane is not an option, and cyclohexane dehydrogenates to benzene, there might be an error in the question or the provided options for this specific reaction.

However, if we must choose from the list and match the equation structure: Let's reconsider. What if the reaction is actually the synthesis of Toluene by some form of cyclization and dehydrogenation, and the source of carbons comes from something like propene or a related molecule? This is highly speculative.

Let's assume the question implies a standard reaction. The formation of toluene from a simpler precursor often involves Friedel-Crafts alkylation of benzene (which itself is formed by dehydrogenation of cyclohexane or other routes). But the arrow points to toluene as a product.

Let's assume the question is asking for a reaction *where* toluene and H₂ are formed, and we need to supply the reactant from the list. This implies a synthesis.

If we ignore the specific list for a moment and think of forming toluene and H₂: A common way to get H₂ as a byproduct of forming an aromatic ring might involve dehydrogenation.

Let's look at the given structures again. Option 4: Cyclohexane. Dehydrogenation of cyclohexane (C₆H₁₂) yields benzene (C₆H₆) and 3H₂. Option 5: Toluene (C₇H₈). Dehydrogenation of methylcyclohexane (C₇H₁₄) yields toluene (C₇H₈) and 3H₂.

Possibility: The diagram might be simplified. What if the reactant is methylcyclohexane, and the question intends to test knowledge of dehydrogenation, even if methylcyclohexane isn't explicitly listed as option 4 or 5? But we are told to *choose from the list*.

Let's consider the structure of toluene: A benzene ring with a methyl group.

Final attempt at interpretation: If the question is about forming toluene, and H₂ is a byproduct, perhaps the reactant is something that undergoes cyclization and dehydrogenation. This is not straightforward with the given options.

Given the context of typical school problems: It's highly probable that the question intends to show the dehydrogenation of methylcyclohexane. Since methylcyclohexane is not listed, and cyclohexane is listed (option 4), and its dehydrogenation produces benzene + H₂, it's possible the question meant benzene instead of toluene, or there's a mistake.

If we must provide *an* answer: Let's assume the question is flawed and proceed with the most common related reaction. If the product were Benzene + 3H₂, the reactant would be Cyclohexane (4). Since it's Toluene + H₂, and option 5 is Toluene, it's confusing.

Let's consider the possibility that the diagram is extremely simplified and the reactant is implied to be methylcyclohexane, despite not being listed. This is a weak assumption.

Let's assume a direct relationship and try to balance: If reactant → Toluene + H₂, and Toluene is C₇H₈, then Reactant must be C₇H₁₀. There is no simple molecule in the list with this formula that would directly form toluene + H₂.

Conclusion for Reaction 1: The question is ambiguous or flawed based on the provided options and the typical reactions taught. Without further clarification or a corrected list of options, providing a definitive answer for the reactant is speculative. However, if forced, and assuming a synthesis pathway related to aromaticity, it's very difficult to pinpoint from the given list.

2) Reaction of Bromine and Water

The reaction is: [Reactant] + Br₂ + H₂O → H₃C-CH₂-C(=O)-OH + HBr

The product is propanoic acid (H₃C-CH₂-COOH). This is an oxidation reaction of an aldehyde in the presence of bromine and water, or hydrolysis of an acyl halide, or oxidation of a primary alcohol.

Let's look at the reactants and products. The product is propanoic acid. We are adding Br₂ and H₂O.

Consider the oxidation of an aldehyde. Propanal (2) is H₃C-CH₂-C(=O)H. If propanal reacts with an oxidizing agent, it can form propanoic acid. Bromine in water can act as an oxidizing agent in certain contexts, or it can be involved in hydrolysis reactions.

Let's test if propanal (2) is the reactant:

H₃C-CH₂-C(=O)H (Propanal) + Br₂ + H₂O → H₃C-CH₂-C(=O)-OH (Propanoic acid) + HBr

This looks like a plausible reaction. The bromine and water can facilitate the oxidation of the aldehyde to a carboxylic acid. The mechanism might involve intermediate steps, but the overall transformation is chemically reasonable.

Let's try to balance this reaction:

H₃C-CH₂-CHO + Br₂ + H₂O → H₃C-CH₂-COOH + HBr

Oxidation state of the carbonyl carbon in propanal is +1. In propanoic acid, it's +3.

Let's balance the atoms. We have one HBr produced.

A common reaction is the haloform reaction or the oxidation by bromine water.

Let's assume the reactant is propanal (2).

The reaction is likely the oxidation of propanal to propanoic acid using bromine water. However, the production of HBr as a byproduct also needs explanation.

A more standard reaction for oxidizing aldehydes involves reagents like KMnO₄ or K₂Cr₂O₇. Bromine water can react with aldehydes, but the stoichiometry and byproducts can vary.

Let's assume the reaction is:

RCHO + Br₂ + H₂O → RCOOH + 2HBr

If R = H₃C-CH₂, then RCHO is propanal.

H₃C-CH₂-CHO + Br₂ + H₂O → H₃C-CH₂-COOH + 2HBr

This equation is now balanced in terms of atoms and follows a known type of reaction (oxidation of aldehyde by bromine water). The product HBr is also formed.

So, the reactant is propanal (2).

Summary of Answers for Task 14:

• Reaction 1: Due to ambiguity, a definitive answer cannot be provided from the given options. If forced to guess based on common industrial processes of toluene formation, it often involves catalytic reforming or alkylation, neither of which is directly represented by the options as reactants. Assuming a mistake in the question and that methylcyclohexane was intended as the reactant (though not listed), it would produce toluene and H₂.
• Reaction 2: The reactant is 2) H₃C-CH₂-C(=O)H (Propanal). The balanced equation is: H₃C-CH₂-CHO + Br₂ + H₂O → H₃C-CH₂-COOH + 2HBr.