Chemistry 9701 · AS & A Level · Hydroxy compounds

Hydroxy compounds — practice question

Calcitriol is a steroid hormone present in human blood.
(a)[1]

Give the number of primary, secondary and tertiary alcohol groups present in one molecule of calcitriol. Primary \dotfill\dotfill\dotfill\dotfill\dotfill\dotfill\dotfill\dotfill secondary \dotfill\dotfill\dotfill\dotfill\dotfill\dotfill\dotfill\dotfill tertiary \dotfill\dotfill\dotfill\dotfill\dotfill\dotfill\dotfill\dotfill

(b)[1]

Give the number of chiral carbon atoms present in one molecule of calcitriol.

(c)[1]

Calcitriol shows geometrical isomerism. Give the number of geometrical isomers of calcitriol, including calcitriol.

(d)

A sample of calcitriol is treated with an excess of hot, concentrated, acidified potassium manganate(VII). This reaction gives three different carbon-containing products. One of these three products, X, is shown.

(d(i))[1]

Predict the number of peaks in the carbon-13 NMR spectrum of X.

(d(ii))[3]

For the carbon-13 NMR spectrum of X, state the expected chemical shift ranges $(\delta)$ of the peaks predicted in (i) and the number of peaks in each range.

(d(iii))[1]

Predict the number of peaks this compound would show in its proton NMR spectrum.

(d(iv))[2]

For each of the peaks in the proton NMR spectrum you have identified in (iii), give the expected splitting pattern. Explain your reasoning.

(e)

In addition to the product shown in (d), two other carbon-containing products are produced when a sample of calcitriol is treated with an excess of hot, concentrated, acidified potassium manganate(VII).

(e(i))[2]

Of these two other carbon-containing products, identify the product with the smaller molecular mass. Explain how this product is formed.

(e(ii))[1]

Of these two other carbon-containing products, identify the product with the larger molecular mass by drawing its skeletal formula in the space below.

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