Hi. can you help me with this problem ? The pre lab work In this experiment, you

Question

Hi. can you help me with this problem ? The pre lab work

In this experiment, you will first predict the order of reactivity of six hydrocarbons toward bromination. You will then test your predictions by carrying out the bromination reactions o compounds. The instructor may also be direct you to test one o f the six r more additional related hydrocarbons. Pre-lab Work (Write this in your notebook, as well as on a separate sheet of loose-leaf paper asked to turn the separate sheet at the start of lab a separate sheet of loose-leaf paper. You may be For each of the hydrocarbons shown below, identify all of the types of C-H bonds and list their bond strengths. For example, toluene has aromatic hydrogens (110 kcal/mol) and primary benzylic hydrogens (85 kcal/mol. Use the table on the previous page to help you. Use this information to predict which of your compounds would react fastest, then second fastest, and so forth CH(CH3)2C(CH3)3 CH CH 3 H2CH3 2 CH 2 Toluene Isopropylbenzene Cyclohexane Ethylbenzene (Cuimene) (Cumene) tert-Butylbenzene Methylcyclohexane Safety Alert! 1. Bromine is corosive and a severe respiratory irritant. Do not breathe its vapors or allow it to contact your Bromine is corrosive and a severe respiratory irritant. Do not breathe its vapors or allow it to contact your skin. Perform all transfers of bromine in a hood, and wear rubber gloves. If you get bromine on your skin, wash the area immediately with soap and warm water and notify your instructor. Dispense the bromine solution in the hood. Avoid excessive inhalation of the vapors of any of the materials being used in this experiment 2. 3. Procedure IMPORTANT! Record your predictions in your notebook before you carry out the experiment 2 Obtain 12 clean, dry test tubes. Label six of them, one for each hydrocarbon being tested Add 10 drops of each hydrocarbon to its labeled tube Add 10 drops of a 10 M solution of Br2 in CH2Cl2 to each of the remaining six tubes ry to add the same amount of bromime to each tu use variations in the amounts of bromine can fead to misleading resu tubes and agitate the tubes to mix the contents. Record the start time. When the characteristic bromine color ades com apsed. Some of the reactions are quite fast and take less thar O seconds, so you may have to repeat the analysis of some tubes to accurately measure the time. )

Explanation / Answer

In toluene:
aromatic hydrogen (attached in ring) : 110 Kcal/mol
primary benzylic hydrogen (attach to C) : 85 Kcal/mol

In Ethylbenzene:
aromatic hydrogen (attached in ring) : 110 Kcal/mol
primary benzylic hydrogen (attach to CH3) : 85 Kcal/mol
secondary benzylic hydrogen (attach to CH2) : 82 Kcal/mol

In isopropyllbenzene:
aromatic hydrogen (attached in ring) : 110 Kcal/mol
primary benzylic hydrogen (attach to CH3) : 85 Kcal/mol
tertiary benzylic hydrogen (attach to CH) : 79 Kcal/mol

In tertbutyllbenzene:
aromatic hydrogen (attached in ring) : 110 Kcal/mol
primary benzylic hydrogen (attach to CH3) : 85 Kcal/mol

In cyclohexane:
secondary alkyl hydrogen (H in CH2) : 95 Kcal/mol

In Methylcyclohexane:
primary alkyl hydrogen (H in CH3) : 98 Kcal/mol
secondary alkyl hydrogen (H in CH2) : 95 Kcal/mol
tertiary alkyl hydrogen (H in CH) : 92 Kcal/mol

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