Question

Polymerization of vinyl acetate gives poly(vinyl acetate). Hydrolysis of this polymer in aqueous sodium hydroxide gives the useful water-soluble polymer poly(vinyl alcohol). Draw the repeat units of both poly(vinyl acetate) and poly(vinyl alcohol).

Short answer

Answer: The repeat unit for poly(vinyl acetate) is [-CH2-CH(OCOCH3)-]_{n}, and the repeat unit for poly(vinyl alcohol) is [-CH2-CH(OH)-]_{n}.

Step-by-step solution

Understand the structure of vinyl acetate

Vinyl acetate is an organic compound with the formula CH3COOCH=CH2. It consists of a vinyl group (CH=CH2) bonded to an acetate group (CH3COO).

Draw the repeat unit of poly(vinyl acetate)

Poly(vinyl acetate) is formed by the polymerization of vinyl acetate monomers. During this process, the double bond in the vinyl group opens up and forms a single bond with another vinyl acetate molecule. This process repeats, creating a long chain of vinyl acetate molecules. The repeat unit for poly(vinyl acetate) can be represented as: [-CH2-CH(OCOCH3)-]_{n} In this formula, the square brackets denote the repeat unit and "n" represents the number of repeating units in the polymer chain.

Understand the hydrolysis process of poly(vinyl acetate)

During the hydrolysis process, poly(vinyl acetate) reacts with water and sodium hydroxide, which breaks the ester linkages of the acetate groups and replaces them with hydroxyl groups (OH) to form poly(vinyl alcohol).

Draw the repeat unit of poly(vinyl alcohol)

After the hydrolysis process, the acetate groups in the poly(vinyl acetate) are replaced by hydroxyl groups. The repeat unit for poly(vinyl alcohol) can be represented as: [-CH2-CH(OH)-]_{n} In this formula, the square brackets denote the repeat unit, and "n" represents the number of repeating units in the polymer chain.

Key concepts

Vinyl Acetate

Vinyl acetate is an organic compound used as a building block in polymer chemistry. Its chemical formula is CH\(_3\)COOCH=CH\(_2\). To better visualize its structure:

• CH\(_3\)COO- represents the acetate group.
• CH=CH\(_2\) is the vinyl group, which contains a double-bonded carbon pair.

These two parts form the vinyl acetate molecule, where the vinyl group is directly bonded to the acetate group. This unique structure allows vinyl acetate to readily polymerize, making it a valuable monomer in creating polymers like poly(vinyl acetate). Through a process known as polymerization, these molecules link together in long chains, forming more complex chemical structures.

Poly(vinyl acetate)

Poly(vinyl acetate), often abbreviated as PVAc, is a polymer that results from the polymerization of vinyl acetate monomers. During this reaction, the following key changes occur:

• The double bond in the vinyl group of each monomer opens up.
• This bond formation repeats, linking monomers together into a polymer chain.

The repeat unit for poly(vinyl acetate) is represented as [-CH\(_2\)-CH(OCOCH\(_3\))-]_\{n\}, where "n" indicates the number of repeating units in the polymer. This structure provides PVAc with its distinct properties, such as flexibility and adhesive qualities, making it a common component in products like paints and adhesives.

Hydrolysis

Hydrolysis is a chemical reaction involving the breaking of a bond in a molecule using water. It's crucial in the transformation of poly(vinyl acetate) into poly(vinyl alcohol). Here's how the process works:

• Poly(vinyl acetate) is treated with water and sodium hydroxide.
• The ester linkages (RCOO-R) in PVAc are broken down.
• The acetate groups are replaced with hydroxyl (-OH) groups.

This transformation changes both the chemical and physical properties of the original polymer, resulting in a substance that dissolves in water, thus becoming poly(vinyl alcohol). Hydrolysis is an important reaction in organic chemistry, allowing for the conversion of various synthetic polymers into more useful forms.

Poly(vinyl alcohol)

Poly(vinyl alcohol), or PVA, emerges from the hydrolysis of poly(vinyl acetate). Unlike PVAc, PVA is water-soluble. This trait significantly broadens its application range. The structure of poly(vinyl alcohol) can be represented as [-CH\(_2\)-CH(OH)-]_\{n\}, showing the replacement of acetate groups with hydroxyl groups.
Key properties of PVA include:

• Good film-forming abilities, which makes it an excellent barrier material.
• Adhesive qualities suitable for various binding and coating uses.
• Sensitivity to water, allowing it to dissolve when needed.

Because of these characteristics, PVA is widely used in applications like water-soluble films, adhesives, and textile sizing in industries.