Given the ratio of products obtained in the bromination of propane, calculate the relative reactivity of a 1° C–H bond to a 2° C–H bond under these conditions.

검증된 단계별 안내

Step 1: Analyze the given data. The bromination of propane produces two products: 2-bromopropane (97%) and 1-bromopropane (3%). This indicates that bromination occurs preferentially at the secondary (2°) carbon over the primary (1°) carbon.

Step 2: Determine the number of equivalent hydrogen atoms available for substitution at each type of carbon. Propane has 6 primary (1°) hydrogens and 2 secondary (2°) hydrogens.

Step 3: Calculate the product formation per hydrogen type. Divide the percentage yield of each product by the number of hydrogens of the corresponding type. For 2-bromopropane, divide 97% by 2 hydrogens. For 1-bromopropane, divide 3% by 6 hydrogens.

Step 4: Compare the relative reactivity of the 1° C–H bond to the 2° C–H bond. The relative reactivity is the ratio of the product formation per hydrogen type for the secondary hydrogens to the primary hydrogens.

Step 5: Interpret the result. A higher relative reactivity for the 2° C–H bond indicates that bromination is more favorable at the secondary carbon under these conditions.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Bromination Mechanism

Bromination of alkanes involves a free radical mechanism where bromine (Br2) is homolytically cleaved to form bromine radicals. These radicals then abstract hydrogen atoms from the alkane, leading to the formation of alkyl radicals. The stability of these alkyl radicals influences the product distribution, as more stable radicals will form preferentially.

Reactivity of C-H Bonds

The reactivity of C-H bonds in alkanes varies based on the degree of substitution of the carbon atom to which the hydrogen is attached. Primary (1°) C-H bonds are less reactive than secondary (2°) C-H bonds due to the stability of the resulting radicals; 2° radicals are more stable than 1° radicals, leading to a higher likelihood of bromination at 2° sites.

Product Ratio and Relative Reactivity

The ratio of products formed during bromination reflects the relative reactivity of the different C-H bonds. By analyzing the product distribution, one can deduce the relative reactivity of 1° versus 2° C-H bonds. A higher proportion of products from 2° bromination compared to 1° indicates that 2° C-H bonds are more reactive under the given conditions.