Question

Name (PRINT): Provide a structure consistent with the following molecular formula and spectroscopic data. You will al a correct structure or partial credit for answers given below. Formula: CH.0 IR: 1700 cm (very strong) DE 1630 medium) Provide Structure a) 5 4 3 2 1 ppm (2 pts partial credit) Use the molecular formula to calculate the total number of n-bonds plus rings. (DU) for the molecule. DU = (2 pts partial credit) Use the IR data to indicate what types of bonds/functional groups are present b) c) (2 pts partial credit) What type or proton is giving rise to the downfield singlet (1H) (peak A). What does the chemical shift (between 9 and 10 ppm) tell you? d) (2 pts partial credit) Indicate what type of alkyl group is suggested by the upfield quartet (peak C.2H) and triplet (peak E, 3H). e) (2 pts partial credit) Taking into account both chemical shifts and splitting patterns, indicate what type of group is suggested by the downfield quartet (peak B, TH) and doublet (peak D, 3H).

Answer 1

(a) answer given molecular formula = CH10 total number of bonds and rings DBU = C+1-(H/2)-(X/2)+(N/2) = 6+1-(10/2)-(0/2)+(0/2) = 2 (b) given IR data answer functional groups C=O stretching C=0 1700 cm-1(very strong) 1630 cm-1(medium) C=C stretching C=C (c) Highly deshielded proton is giving downfiled shift singlet indicates that it is not coupling with any H. no near Hydrodens to couple. chemical shift 9 and 10 ppm means the presence of aldehydic proton chemical shift 9 and 10 ppm singlet RH downfield(highly deshielded) upfield - alkyl protons CH, is conncted to CH quartet (peak C, 2H) - multiplicity=3+1=4 H 6-7 triplet (peak E, 3H)— CH, is conncted to CH multiplicity=2+1=3 quartet (e) quartet (peak B, 1H) -CH3 chemical shift 6-7 ppm indicates peak is comimg from Sp2 C- H I T spliting quartet means it is coupling with three protons (CH3) alkene C-H doublet (peak D, 3H) CH3 chemical shift 2 ppm and doublet indicates that CH3 is connected to Sp2 C-H structure