Solvolysis of 3-bromo-3-methyl-1-butyne (M.W. 147) in water at 50 C - PowerPoint PPT Presentation

Solvolysis of 3-bromo-3-methyl-1-butyne (M.W. 147) in water at 50 � C for 12 hours gives two products, A and B. The infrared and mass spectra of product A are shown below: IR spectrum A Mass spectrum A

Solvolysis of 3-bromo-3-methyl-1-butyne (M.W. 147) in water at 50 � C for 12 hours gives two products, A and B. The infrared and mass spectra of product A are shown below: 2100 cm -1 C � � C stretch � � 3300 cm -1 Csp–H < 3000 cm -1 : stretch Csp 3 –H stretch > 3000 cm -1 : ~1600 cm -1 Csp 2 –Hstretch C=C stretch 910 cm -1 625 cm -1 R 2 C=CH 2 bend RC � � � CH bend � Clearly label two features on the IR spectrum indicating Mass spectrum A the functional group class of product A.

Solvolysis of 3-bromo-3-methyl-1-butyne (M.W. 147) in water at 50 � C for 12 hours gives two products, A and B. The infrared and mass spectra of product A are shown below: 2100 cm -1 C � � C stretch � � 3300 cm -1 Csp–H < 3000 cm -1 : stretch Csp 3 –H stretch > 3000 cm -1 : ~1600 cm -1 Csp 2 –Hstretch C=C stretch 910 cm -1 625 cm -1 R 2 C=CH 2 bend RC � � � CH bend � Mass spectrum A � � M + � � Clearly label the molecular ion (M + � ) of the mass spectrum.

Solvolysis of 3-bromo-3-methyl-1-butyne (M.W. 147) in water at 50 � C for 12 hours gives two products, A and B. The infrared and mass spectra of product A are shown below: 2100 cm -1 C � � C stretch � � 3300 cm -1 Csp–H < 3000 cm -1 : stretch Csp 3 –H stretch > 3000 cm -1 : ~1600 cm -1 Csp 2 –Hstretch C=C stretch 910 cm -1 625 cm -1 R 2 C=CH 2 bend RC � � � CH bend � Mass spectrum A � � M + � � The fragment appearing at mass 51 suggests a loss of what functional group from the molecular ion? 66 - 51 = 15 mass units: C (12) + 3 [H (1)] = CH 3 (15)

Solvolysis of 3-bromo-3-methyl-1-butyne (M.W. 147) in water at 50 � C for 12 hours gives two products, A and B. The infrared and mass spectra of product A are shown below: 2100 cm -1 C � � C stretch � � 3300 cm -1 Csp–H < 3000 cm -1 : stretch Csp 3 –H stretch > 3000 cm -1 : ~1600 cm -1 Csp 2 –Hstretch C=C stretch 910 cm -1 625 cm -1 R 2 C=CH 2 bend RC � � � CH bend � Mass spectrum A � � M + � � Provide a structural formula for product A .

Solvolysis of 3-bromo-3-methyl-1-butyne (M.W. 147) in water at 50 � C for 12 hours gives two products, A and B. The infrared and mass spectra of product A are shown below: 2100 cm -1 C � � C stretch � � 3300 cm -1 Csp–H < 3000 cm -1 : stretch Csp 3 –H stretch > 3000 cm -1 : ~1600 cm -1 Csp 2 –Hstretch C=C stretch 910 cm -1 625 cm -1 R 2 C=CH 2 bend RC � � � CH bend � Mass spectrum A � � M + � � Product B has molecular formula C 5 H 8 O. Provide a structural formula for product B