12 -2 1 (a) Deuterium has twicethe mass of hydrogen,but similar spring constant, k.Comparethe frequencyof C-D vibration to C-H vibration bysetting upa ratio, ch an ging only th e mass (su bs titute 2 m for m). = = �lt2 = 0.707 Vo = 0.7 07 vH = 0.7 07 (3000 em-I) '" 2100 cm-1 (b) The func tional gr oup mos t lik ely to be c onfus ed with a C- D str etc h is the alk yne (c ar bon-c ar bontn ple bond), whichappears in th e same region and is of ten ver y weak. 12-22 ( �r-m/z 1 14 [+r � m/z 1 14 r*r � m/z 14 + � m/z 57 1+ m/z 57 �. m/z 57 a 1° c ar boc at ion- not favor able a 2° car boc at ion-r eas onable a 3° car boc ation-t he best The most likely fragmentation of 2,2,3,3-tetramethylbutane will give a 3°carbocation, the mostst able of the c ommon alkylc at ions. The molecu lar ion s hould be s mall ornon- exis tent while m/z 57 is likely tobe the basepeak, wher eas t he molecu lar ion peaks will be mor e pr omi nent for n -oc tane and for 3,4- dimethylh exane . 12 -2 3 (a) Th e infor mat ion t hat this mys teryc ompound is a hydr oc ar bon mak es
This is the end of the preview.
access the rest of the document.
Trigraph, ofh yd ogen,bu, bo tn ple, mole ula ion, om nent fo, -D vib ation