94年國立中央大學化學所有機化學

2-Bromopropane can undergo S_N2, S_N1, E2, or E1 reaction as the majorreaction pathway, depending on the reaction conditions. Give on example for eachof these four types of reactions for 2-bromopropane with reaction conditions(reagents, solvents, and temperature) and the structure of products.

When acetone is treated with anhydrous ammonia in the presence of anhydrouscalcium chloride (a common drying agent), crystalline product A is obtained onconcentration of the organic liquid phase of the reaction mixture.
These are spectral data for product A:
MS(m/z): 155(M⁺), 140
IR (cm^-1): 3350(sharp), 2850-2960, 1705
¹H NMR (δ): 2.3 (s, 4H), 1.7 (1H; disappears in D2O), and 1.2 (s, 12H)
(1) What is the structure of A (assign the peaks for IR and NMR)? 
(2) Propose a mechanism for formation of A (use curved arrows). 

Explain the following observations.
(1) Cycloheptatrienone (D) is very stable. Cyclopentadienone (E) by contrast isquite unstable.

Predict the structures of the following.

Classify the following configuration as A, E or T in complexes having O_hsymmetry. Some of these configurations represent excited states.

Predict the relative order of IR(NO) frequencies for the following compounds.

BrCH₂CH₂CH₂Mn(CO)₅ is formed by reaction of Mn(CO)₅⁻ with1,3-dibromopropane. However, the reaction does not stop here; the productreacts with additional Mn(CO)5⁻ to yield a carbene complex. Propose astructure for this complex and suggest a mechanism for its formation.

Three isomers of W₂C_l4(NHR)₂(PMe₃)₂ are possible. Determine the pointgroup of each.

BrF₃, I₂C_l6 and even H₂SO₄ are widely used as nonaqueous solvents. Theyundergo significant autodissociation. Show the corrsponding reaction.