Question

Grignard Lab...

Preparation of PhMgBr...

.02 mole Mg

.0021 moles of bromobenzene

Synthesis of Triphenylmethanol

Moles of benzophenone =.002

weight of crude product after washing with petroleum ether+ .157 g

CALCULATE PERCENT YIELD OF PRODUCT???

After recrystallization

weight of product = .132 g

% YEILD OF PRODUCT??? WITH CALCULATIONS

Answer 1

FOR THE PREPARATION OF TRIPHENYLMETHANOL, THE THEORETICAL YIELD CAN BE CALCULATED BY MULTIPLYING THE MOLES OF LIMITING AGENT BY ITS RATIO WITH THE PRODUCT AND FURTHER BY MOLECULAR WEIGHT OF THE PRODUCT. FOR THE GIVEN REACTION, THEORETICAL YIELD IS EQAL TO

0.0021 MOLES OF BROMOBENZENE (LIMITING AGENT)* (1 MOLE PRODUCT/ 1 MOLE BROMOBENZENE) * (260.34 GM TRIPHENYLMETHANOL/1 MOLE TRIPHENYLMETHANOL)

THIS IS EQAL TO 0.547 GM PDT. (UNDER IDEAL CONDITIONS)

PRACTICALLY YOU HAVE GOT 0.157 GM CRUDE PRODUCT FOR WHICH THE PERCENT YIELD WILL BE 28.7% AND AFTER RECRYSALLIZATION, THE PERCENT YIELD, FOR 0.132 GM PURE PDT., WILL BE 24.13% USING FOLLOWING FORMULA.

AS UNDER IDEAL CONDITION, THEORETICAL YIELD GIVES 100% RESULTS THEN ACTUAL YIELD GIVES HOW MUCH PERCENT? THAT IS,

THEORETICAL YIELD/ PRACTICAL (ACTUAL) YIELD*100

THIS WILL GIVE YOU FINAL PERCENT YIELD OF THE PURE TRIPHENYLMETHANOL.