1. You are provided with the molecular formula \( \mathrm{C} 4 \mathrm{H} 6 \mathrm{O} \) i) Draw all possible isomers of carbonyl compound that confirm to the formula above (2mks) ii) Compound \( X \), one of the isomers in (i) above gave a positive lodoform test (iodine in (a) \( \mathrm{NaOH} \) to give compounds \( \mathrm{Y} \) and \( \mathrm{Z} \). Identify compounds \( \mathrm{X} \) and \( \mathrm{Y} \) and \( \mathrm{Z} \) (2mks) 2. a) The steps the mechanism of the acid hydrolysis of the amides are similar to that of ester. Write down the three mechanisms in the three steps (3mks) b). In the Aldol condensation of propanone and ethanol in presence of a basic medium, four different aldol products are obtained. Draw structures of the expected products and give their systematic names (3mks) 3) How can the following amines be prepared using reductive animation reactions? Show all precursor if more than one is possible (3mks) a) b) c) 4a) State three properties of amines (1.5mks) b) Which suitable examples, distinguish between primary and secondary amines (2mks) a) Give a simple visual chemical test including the observations, you w ould use to differentiate between the follow ing i) and \( (2 \mathrm{mks}) \) ii) and iii) \( (2 \mathrm{mks}) \) 3. Explain the following using appropriate equations and or structures i) In keto-enol tautomerism, the keto form of propanone is normally preferred over the enol from. However, the enol form of 2,4 - pentanedioic is preferred over the keto form (1mks) ii) Amines are more basic than amide: \( (1 \mathrm{mks}) \) iii) The reaction of an acid chloride with an alcohol to give an ester is usually
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i) The possible isomers of carbonyl compound with the molecular formula C4H6O are but-3-en-2-one, but-2-en-2-one, and butan-2-one. ii) Compound X that gives a positive iodoform test must have a methyl ketone group. Therefore, compound X is butan-2-one. Compound Y Show moreā¦
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The reduction of aldehydes and ketones with a suitable hydride-containing reducing agent is a good way of synthesizing alcohols. This approach would be even more effective if, instead of a hydride, we could use a source of nucleophilic carbon. Attack by a carbon atom on a carbonyl group would give an alcohol and simultaneously form a carbon-to-carbon bond. How can we make a C atom in an alkane nucleophilic? This was achieved by Victor Grignard, who created the organometallic reagent $\mathrm{R}-\mathrm{MgBr},$ with the following reaction in diethyl ether: $$\mathrm{R}-\mathrm{Br}+\mathrm{Mg} \longrightarrow \mathrm{R}-\mathrm{MgBr}$$ The Grignard reagent is rarely isolated. It is formed in solution and used immediately in the desired reaction. The alkylmetal bond is highly polar, with the partial negative charge on the $\mathrm{C}$ atom, which makes the C atom highly nucleophilic. The Grignard reagent $(\mathrm{R}-\mathrm{MgBr})$ can attack a carbonyl group in an aldehyde or ketone as follows: Addition of dilute aqueous acid solution to the metal alkoxide furnishes the alcohol. The important synthetic consequence of this procedure is that we have prepared a product with more carbon atoms than present in the starting material. A simple starting material can be transformed into a more complex molecule. (a) What is the product of the reaction between methanal and the Grignard reagent formed from 1-bromobutane after the addition of dilute acid? (b) By using a Grignard reagent, devise a synthesis for 2-hexanol. (c) By using a Grignard reagent, devise a synthesis for 2 -methyl- 2 -hexanol. (d) Grignard reagents can also be formed with aryl halides, such as chlorobenzene. What would be the product of the reaction between the Grignard reagent of chlorobenzene and propanone? Can you think of an alternative synthesis of this product, again using a Grignard reagent? (e) The basicity of the $C$ atom bound to the magnesium in the Grignard reagent can be used to make Grignard reagents of terminal alkynes. Write the equation of the reaction between ethylmagnesium bromide and 1-hexyne. [Hint: Ethane is evolved.] (f) By using a Grignard reagent, suggest a synthesis for 2 -heptyn-1-ol.
Your answer is incorrect. Try again. 8.31a 1) BH3Ā·THF 2) H2O2, NaOH Modify the given carbon skeleton to draw the major product(s). If a racemic mixture of enantiomers is expected, draw both enantiomers. Note: you can select a structure and use Copy and Paste to save drawing time. 8.31e H3O+ Modify the given carbon skeleton to draw the major product(s). If a racemic mixture of enantiomers is expected, draw both enantiomers. Note: you can select a structure and use Copy and Paste to save drawing time. 8.31f HBr Modify the given carbon skeleton to draw the major product(s). If a racemic mixture of enantiomers is expected, draw both enantiomers. Note: you can select a structure and use Copy and Paste to save drawing time. 8.31g 1) RCO3H 2) H3O+ Modify the given carbon skeleton to draw the major product(s). If a racemic mixture of enantiomers is expected, draw both enantiomers. Note: you can select a structure and use Copy and Paste to save drawing time. 8.31h 1) BH3Ā·THF 2) H2O2, NaOH Modify the given carbon skeleton to draw the major product(s). If a racemic mixture of enantiomers is expected, draw both enantiomers. Note: you can select a structure and use Copy and Paste to save drawing time. 8.31i OsO4 (catalytic) NMO Modify the given carbon skeleton to draw the major product(s). If a racemic mixture of enantiomers is expected, draw both enantiomers. Note: you can select a structure and use Copy and Paste to save drawing time.
Hitendra S.
The following questions are based on the reactions of ethyl ethanoate $(1) \text { shown below. (Sections } 24.2 \text { and } 24.3)$ (a) Give appropriate reagents for converting 1 into 2 . Is this an example of an oxidation or a reduction reaction? (b) Give the structure of organic compound 3 (c) Oxygen-18 labelling is often used to establish the mechanism of a reaction. A $^{16}$ O oxygen in a starting material is replaced by an $^{18} \mathrm{O}$ atom and the position of the $^{18} \mathrm{O}$ atom at the end of the reaction recorded using mass spectrometry (Section $12.1, \text { p.558 })$ (i) Draw a reaction mechanism to show how 1 is converted into 4 and $\mathrm{EtOH}$. (ii) If 1 is heated with $\mathrm{H}_{2}^{18} \mathrm{O}$ and $\mathrm{H}^{+}$, where does the $^{18} \mathrm{O}$ atom appear at the end of the reaction? (iii) If ethyl ethanoate, labelled with $^{18} \mathrm{O}$ as shown below, is heated with $\mathrm{H}_{2} \mathrm{O} / \mathrm{H}^{+}$, where does the $^{18} \mathrm{O}$ atom appear at the end of the reaction? (d) Draw a reaction mechanism to show how 1 is converted into 5 (e) Draw the major enol form of compound 5
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