Organic 1

Question 1

Degree of unsaturation formula?

Answer 1

IHD= (2C +2-H-X+N) /2

Question 2

How is the molecular ion created?

Answer 2

It is the initial charges molecules created by the impact of an electron.

Question 3

Loss of 16 in a mass spec is normally what?

Answer 3

Either oxygen or CH4.

Question 4

Which bond, in reference to the most stable point/heteroatom is cleaved usually?

Answer 4

Alpha bond

Question 5

In mass spec what does a loss of 29m/z correlate to normally?

Answer 5

C2H5

Question 6

What happens in retro-diels-alder reactions?

Answer 6

The double bond from an indole or alkene pushes into a cyclocarbon breaking it if one side is fully substituted.

Question 7

What type of cleavage is the McLafferty rearrangement and what functional group is required for it?

Answer 7

Beta cleavage and carbonyl group. Includes a proton rearrangement from a carbon fat enough away to twist round.

Question 8

Onium reaction: what is the main requirement?

Answer 8

A positively charged heteroatom: ammonium, oxonium and sulfonium etc.

Question 9

Isotope patterns: chlorine ratios for Cl1 and Cl2?

Answer 9

Cl1:X:(x+2) = 100:32

Cl2:X:(x+2):(x+4) = 100:64:10

35Cl and 37Cl

Question 10

Isotope pattern ratios: one Br and 2 Br

What are its isotopes?

Answer 10

Br1:x:(x+2) = 100:98

Br2:x:(x+2):(x+4)= 51:100:48

79Br and 81Br

Question 11

IR selection rule?

Answer 11

IR transitions are allowed if the dipole moment changes during transition. The molecule must have a permanent or available dipole.

Question 12

(A) Free OH groups appear at what wavelength in IR?

(B) N-H?

(C) alkyne-H?

Answer 12

(A) 3600

B 3500-3300

C 3300

Question 13

(A) Alkenes-h appear where in IR?

(B) c-c-h

(C) s-h

Answer 13

(A) 3100-3000

(B) 3000-2850

(C) 2600-2550

Question 14

IR AREAS:

(A) carboxylic acid group

(B) acid chlorides

(C) esters

(D) aldehydes

(E) ketones

Answer 14

(A) 1850-1800

(B) 1815-1790

(C) 1750-1735

(D) 1740-1720

(E) 1725-1705

Question 15

Uv/vis spectroscopy selection rule?

Answer 15

Got to be symmetrically allowed. All about absorbing photons and exciting electrons into different energy levels.

Question 16

Why can’t you do NMR on carbon 12?

Answer 16

Carbon-12 has an even mass number and therefore is divided equally between protons and neutrons. Atoms with whole or 0 number spins do not exhibit nuclear magnetic moments and thus are NMR inactive.

Question 17

Which atoms have a nuclear spin of I= 1/2 ?

Answer 17

1H, 13C, 31P and 19F

Question 18

What is the size of ciscoupling and transcoupling between 1Hs across a double bond?

Answer 18

Near 10.5-12Hz and upwardsof 18Hz, respectfully. Double bonds do not rotate!!!

Question 19

Ratios for C12 and C13 in mass spec?

Answer 19

100:(1.1 * n)

N being number of carbon atoms present

Question 20

If a molecule has one nitrogen, are there an odd number of hydrogens present, hence an odd molecular weight?

Answer 20

Yes, nitrogen can form three bonds (an odd number) unlike any other atoms like C, O and S. This means there must be an odd number of Hs and therefore an odd molecular weight. Same applies the other way.

Question 21

How to calculate chemical shift, in ppm of a given nucleus?

Answer 21

Frequency (Hz) - frequency of TMS (Hz)/ frequency TMS (MHz)