Devise syntheses for the following molecules. You may start with benzene, methyl alcohol, sodium methoxide, ethyl alcohol, sodium ethoxide, butyl alcohol (BuOH), phosgene, and propanoic acid as your sources of carbon. You may also use any inorganic reagent and solvents as needed.

To begin with organic synthesis planning, it's crucial to understand the molecular structure of the target molecule. This involves examining the molecule's functional groups, such as alcohols, carboxylic acids, or amines, as well as its carbon skeleton framework. These elements determine the reactivity and the types of reactions the molecule can undergo.
For instance, if your target molecule contains an ester functional group, you'll need to consider steps that either introduce this group or transform another functional group into an ester. This process helps in conceptualizing the final product and understanding its chemical properties, which is foundational for planning a successful synthesis.

Selecting the appropriate starting materials is a key step in organic synthesis. The list provided in the exercise includes benzene, methyl alcohol, sodium methoxide, ethyl alcohol, sodium ethoxide, butyl alcohol, phosgene, and propanoic acid. These starting materials act as your building blocks.
Your choice should depend on the complexity and the functional groups in the target molecule. For example, if the target is a benzene derivative, starting from benzene is logical. The properties of these reagents, like solubility and reactivity, also influence their selection. This careful planning ensures you have the necessary components to construct the desired molecule efficiently.

Mapping out the synthetic route involves determining the sequence of chemical reactions needed to convert the starting materials into the target molecule. This step requires a clear understanding of organic reaction mechanisms and the conditions under which they occur.
You’ll outline each reaction, considering intermediate compounds that may form and the feasibility of each step. This process often involves retrosynthetic analysis, where you deconstruct the target molecule backwards to the starting materials. By doing so, you visualize a logical pathway that details how each component will combine to form the final structure.

Every chemical reaction requires specific conditions to proceed efficiently, such as temperature, pressure, and solvent choice. These conditions are crucial because they influence the reaction rate, yield, and purity of the products.
For example, some reactions may require heating under reflux, while others might need an inert atmosphere to avoid unwanted side reactions. The choice of solvent can also affect solubility and reaction kinetics. Understanding these conditions and adjusting them as necessary ensures that each step in your synthetic route proceeds smoothly and effectively.

Yield optimization is about maximizing the amount of target molecule produced while minimizing by-products. After planning and executing the synthesis, evaluating the yield is essential.
This involves testing different reaction conditions to determine which ones produce the highest yield of the desired product. Factors like reagent concentrations, reaction times, and purification methods all play a role in optimization. The goal is to refine each step to ensure that not only is the synthesis feasible but also efficient in producing the highest amount of pure final product possible.