Sketch the percentage tautomeric form of Ketoacetic ester and how would you use it to synthesize 2-butanone.

here are the solutions for questions 3, 4, and 5:

Question 3:

a) Structures of the following compounds:

(i) Cyclohexane-1,2-dione:

$$\boxed{\begin{smallmatrix} \text{O} \\ \text{//} \\ \text{C} \\ \text{/} \quad \text{\\} \\ \text{CH}_2 \quad \text{C} \\ \text{|} \quad \text{//} \\ \text{CH}_2 \quad \text{O} \\ \text{/} \quad \text{\\} \\ \text{CH}_2-\text{CH}_2 \end{smallmatrix} \text{ (cyclic, 6-membered ring)}}$$

(ii) Cyclohexanone:

$$\boxed{\begin{smallmatrix} \text{O} \\ \text{//} \\ \text{C} \\ \text{/} \quad \text{\\} \\ \text{CH}_2 \quad \text{CH}_2 \\ \text{|} \quad \text{|} \\ \text{CH}_2 \quad \text{CH}_2 \\ \text{/} \quad \text{\\} \\ \text{CH}_2-\text{CH}_2 \end{smallmatrix} \text{ (cyclic, 6-membered ring)}}$$

(iii) Piperitone oxide:

$$\boxed{\begin{smallmatrix} \quad \quad \text{CH}_3 \\ \quad \quad \text{|} \\ \quad \quad \text{CH} \\ \quad \quad \text{/} \quad \text{\\} \\ \text{CH}_3-\text{C} \quad \quad \text{CH}_2 \\ \quad \text{//} \quad \quad \text{|} \\ \quad \text{O} \quad \quad \text{CH}_2 \\ \quad \text{/} \quad \quad \text{\\} \\ \quad \text{C} \quad \quad \text{CH} \\ \quad \text{|} \quad \quad \text{/} \\ \quad \text{CH}_2-\text{CH} \\ \quad \quad \text{|} \\ \quad \quad \text{CH}_3 \end{smallmatrix} \text{ (cyclic, 6-membered ring with isopropyl and methyl groups, and an epoxide)}}$$

(iv) Diphenol (assuming 1,2-benzenediol, catechol):

$$\boxed{\mathrm{C_6H_4(OH)_2 \text{ (ortho-)} \text{ or } \begin{smallmatrix} \quad \text{OH} \\ \quad \text{|} \\ \quad \text{C} \\ \text{//} \quad \text{\\} \\ \text{HC} \quad \quad \text{C-OH} \\ \text{|} \quad \quad \text{|} \\ \text{HC} \quad \quad \text{CH} \\ \text{//} \quad \text{\\} \\ \quad \text{C} \end{smallmatrix}}}$$

(v) 3,3-dimethylcyclohexane-1,2-dione:

$$\boxed{\begin{smallmatrix} \text{O} \\ \text{//} \\ \text{C} \\ \text{/} \quad \text{\\} \\ \text{C(CH}_3)_2 \quad \text{C} \\ \text{|} \quad \text{//} \\ \text{CH}_2 \quad \text{O} \\ \text{/} \quad \text{\\} \\ \text{CH}_2-\text{CH}_2 \end{smallmatrix} \text{ (cyclic, 6-membered ring)}}$$

b) Two methods of preparing diols:

1. Hydroxylation of alkenes: Alkenes can be converted to vicinal diols (1,2-diols) using reagents like cold, dilute, alkaline potassium permanganate ($\mathrm{KMnO_4}$) or osmium tetroxide ($\mathrm{OsO_4}$) followed by reduction. Equation (using $\mathrm{KMnO_4}$): $$\mathrm{RCH=CHR' + KMnO_4 \text{ (cold, dilute, alkaline)} \longrightarrow RCH(OH)CH(OH)R'}$$
2. Hydrolysis of epoxides: Epoxides (oxiranes) can be hydrolyzed under acidic or basic conditions to yield vicinal diols. Equation (acid-catalyzed hydrolysis): $$\begin{bmatrix} \text{RCH} \\ \text{/} \\ \text{O} \\ \text{\\} \\ \text{CHR'} \end{bmatrix} \mathrm{+ H_2O \xrightarrow{H^+} RCH(OH)CH(OH)R'}$$

c) Structures of the following compounds:

(i) Propane-1,3-dial (malonaldehyde):

$$\boxed{\mathrm{OHC-CH_2-CHO}}$$

(ii) 1,3-Diphenyl-1,3-dione (assuming 1,3-diphenylpropane-1,3-dione, dibenzoylmethane):

$$\boxed{\mathrm{C_6H_5COCH_2COC_6H_5}}$$

(iii) Pentane-2,4-dione (acetylacetone):

$$\boxed{\mathrm{CH_3COCH_2COCH_3}}$$

(iv) Heptane-2,5-dione:

$$\boxed{\mathrm{CH_3COCH_2CH_2CH_2COCH_3}}$$

(v) 2,5-Hexanedione (assuming "2,5-phenyl dione" is a typo for 2,5-hexanedione, a common $\gamma$-diketone):

$$\boxed{\mathrm{CH_3COCH_2CH_2COCH_3}}$$

Question 4:

a) Structures of glycol dinitrate and glyceryl trinitrate:

• Glycol dinitrate (ethylene glycol dinitrate):

$$\boxed{\mathrm{O_2NOCH_2CH_2ONO_2}}$$

• Glyceryl trinitrate (nitroglycerin):

$$\boxed{\mathrm{O_2NOCH_2CH(ONO_2)CH_2ONO_2}}$$

Three properties of these compounds:

• They are explosive due to the presence of multiple nitrate groups.
• They are highly unstable and sensitive to shock and heat.
• They are powerful vasodilators and are used in medicine (e.g., nitroglycerin for angina).

b) Three properties of polyols:

• They have high boiling points due to extensive intermolecular hydrogen bonding.
• They are typically viscous liquids at room temperature.
• They are highly soluble in water due to the presence of multiple hydroxyl groups.

c) Structure of the simplest triol and reason for elevated boiling point:
The simplest triol is glycerol (propane-1,2,3-triol).

$$\boxed{\mathrm{HOCH_2CH(OH)CH_2OH}}$$

Glycerol has an elevated boiling point (290 °C) because it contains three hydroxyl (-OH) groups. These hydroxyl groups allow for extensive intermolecular hydrogen bonding between glycerol molecules. Hydrogen bonds are strong intermolecular forces that require a significant amount of energy to overcome, leading to a higher boiling point compared to compounds of similar molecular weight but fewer hydroxyl groups.

Question 5:

a) Definition of protein:
A protein is a large, complex biomolecule composed of one or more long chains of amino acid residues. These chains are linked together by peptide bonds and fold into specific three-dimensional structures essential for their biological function.

b) Six examples of body materials where proteins are important constituents:

• Enzymes (e.g., amylase, pepsin)
• Hormones (e.g., insulin, growth hormone)
• Antibodies (immunoglobulins)
• Structural components (e.g., collagen in connective tissue, keratin in hair/nails)
• Transport proteins (e.g., hemoglobin for oxygen transport)
• Muscle fibers (e.g., actin and myosin for muscle contraction)

c) Six biological importance of protein to the human system:

• Catalysis: Enzymes, which are proteins, catalyze nearly all biochemical reactions in the body.
• Structural Support: Proteins like collagen and keratin provide structural integrity to tissues, organs, hair, and skin.
• Transport: Proteins such as hemoglobin transport oxygen, while others transport nutrients, ions, and waste products.
• Immunity: Antibodies (immunoglobulins) are proteins that identify and neutralize foreign invaders like bacteria and viruses.
• Movement: Actin and myosin are proteins responsible for muscle contraction and cellular movement.
• Regulation: Many hormones (e.g., insulin) are proteins that regulate various physiological processes, and receptor proteins mediate cell signaling.