Alkenes：練習問題

When but-2-ene is reacted with an excess of bromine dissolved in an organic solvent, which product is formed?

When 2-methylbut-2-ene reacts with steam in the presence of a phosphoric(V) acid catalyst, a mixture of alcohols is formed. What is the IUPAC name of the major product?

A sample of an unknown liquid is shaken with bromine water. The orange colour of the bromine water disappears immediately. Which of the following compounds could the liquid be?

Which of the following properties of the carbon-carbon double bond is the fundamental reason why alkenes like but-2-ene can exist as geometric isomers?

A section of an addition polymer is found to have the following structure:
\(\text{-(CH(CH}_3\text{)CH(CH}_3\text{))-}_n\)
Which monomer was used to produce this polymer?

Describe the colour change observed and name the functional group produced when ethene is reacted with cold, acidified potassium manganate(VII) solution.

When but-1-ene reacts with hydrogen chloride, two possible products are formed. Name the major product and explain its formation by comparing the relative stability of the carbocation intermediates involved.

State the two types of covalent bonds that make up the carbon-carbon double bond in ethene and identify which bond is more susceptible to attack by electrophiles.

Alkenes are unsaturated hydrocarbons that undergo characteristic addition reactions.

(a) Describe a qualitative chemical test to show that a sample of cyclohexene is unsaturated. State the reagent used and the observation made. (2 points)
(b) When cyclohexene reacts with acidified potassium manganate(VII) at room temperature, a diol is formed. State the color change observed in the reaction mixture and draw the displayed formula of the organic product. (2 points)

But-1-ene reacts with hydrogen bromide, \(\text{HBr}\), via an electrophilic addition mechanism to form two structural isomers, 2-bromobutane and 1-bromobutane.

(a) Draw the displayed formula of but-1-ene and identify the type of isomerism shown by its products. (2 points)
(b) Using curly arrows to show the movement of electron pairs, outline the mechanism for the formation of the major product, 2-bromobutane. (4 points)
(c) Explain, in terms of the stability of the intermediate carbocations, why 2-bromobutane is the major product rather than 1-bromobutane. (2 points)