- 1 Hard Organometallic Reagents Are Important In Many Synthetic Routes Both On In Research Labs And On An Industrial Sc 1 (169.06 KiB) Viewed 10 times
1. Hard organometallic reagents are important in many synthetic
routes, both on in research labs and on an industrial scale. The
nature of the metal has a significant effect on the reactivity
observed. a. With reference to the ionicity and covalency of the
bonding, explain which of organo-lithium or organo-zinc reagents
are considered “harder” and why. [3 marks] b. How does the
reactivity of organocadmium reagents compare to that of equivalent
organozinc reagents? Use this fact to explain why organocadmium
reagents are not widely used. [2 marks] c. Diphenylzinc is dimeric
in the solid side. Predict the degree of aggregation it will
exhibit when dissolved in (i) benzene and (ii) THF, drawing the
resultant structures. Explain your reasoning [4 marks]
1. Hard organometallic reagents are important in many synthetic routes, both on in research labs and on an industrial scale. The nature of the metal has a significant effect on the reactivity observed. a. With reference to the ionicity and covalency of the bonding, explain which of organo-lithium or organo-zinc reagents are considered "harder" and why. [3 marks] b. How does the reactivity of organocadmium reagents compare to that of equivalent organozinc reagents? Use this fact to explain why organocadmium reagents are not widely used. [2 marks] C. Diphenylzinc is dimeric in the solid side. Predict the degree of aggregation it will exhibit when dissolved in (i) benzene and (ii) THF, drawing the resultant structures. Explain your reasoning [4 marks] Salicylaldehyde reacts with diethyl zinc in a 1:1 ratio to form compound A according to the following scheme: он о + Et Zn A + gas On cooling, compound B crystallises from solution, and half an equivalent of diethyl zinc is found to have reformed in solution. B + 0.5 Et Zn d. Identify A, B, and the gas. [3 marks] e. By what process does A transform to B? Sketch a plausible intermediate. [2 marks] f. A reacts cleanly with anhydrous HCl to release a gas and form compound C. Identify C, and explain why this is the sole product. [2 marks] Question continues on next page