(4-methoxyphenyl)methanol

Structure: 

IUPAC Name: 4-methoxyphenyl methanol

C₆H₁₀O₃; MW = 138.17

The molecule contains two oxygens, and from the analysis, contains four double bonds, carbonyls or rings. The large number of degrees of unsaturation strongly suggests an aromatic compound (DU = 4).

The mass spectrum displays a molecular ion, which is the base peak, an m-1 and an m-17, all of which are consistent with a simple alcohol.

The ¹³C spectrum contains six peaks, indicating that the molecule has some elements of symmetry. The quartet at  56 and the triplet at  71 represent a CH₃ and a CH₂ group which are deshielded by electronegative atoms (most likely oxygen); the peaks at  161 – 128 are in the aromatic region; the fact that two doublets and two singlets are observed strongly suggests 1,4-disubstitution.

The proton NMR also shows evidence for aromatic 1,4-disubstitution and suggests that the methyl and methylene are isolated and adjacent to electronegative groups. A peak consistent with an alcoholic OH can also be seen.

The IR is consistent with an aromatic alcohol containing no carbonyl group, suggesting that the second oxygen is involved in an ether linkage.

The simplest structure which is consistent with all of these data would be an aromatic compound containing an alcohol group and a methyl ether, situated 1,4 relative to each other.

IH NMR

The proton NMR has two doublets at  6.9, consistent with aromatic 1,4-disubstitution, and three singlets, areas 3, 2 and 1. The singlets at  3.6 and 4.7 are highly shifted and suggest isolated CH₃ and CH₂ groups adjacent to one or more electronegative atoms or groups. The singlet, area 1, would be consistent with an alcohol.

Predict NMR spectrum

13C NMR

The ¹³C spectrum contains six peaks, indicating that the molecule has some elements of symmetry. The quartet at  56 and the triplet at  71 represent a CH₃ and a CH₂ group which are deshielded by electronegative atoms (most likely oxygen); the peaks at  161 – 128 are in the aromatic region; the fact that two doublets and two singlets are observed strongly suggests 1,4-disubstitution.

¹³C NMR Data: q-56.0; t-71.0; d-114.3; d-128.3; s-160.9; s-133.2

¹³C NMR Assignments: 

MASS

The mass spectrum consists of a molecular ion at 138, which is also the base peak, an m-1 peak at 137, indicating the presence of a labile hydrogen (OH or CHO), and an m-17 peak (loss of HO-). The spectrum is consistent with an alcohol which cannot readily break down to form other stable radical cations.

Mass Spectrum Fragments: 

IR

3400-3200 cm^–1: strong OH peak 3100 cm^–1: small peak, suggesting possible unsaturated CH 2900 cm^–1: strong peak suggesting saturated CH 2200 cm^–1: no unsymmetrical triple bonds 1710 cm^–1: no carbonyl 1610 and 1500 cm^–1: sharp peaks, consistent with aromatic carbon-carbon double bonds

Synthetic Communications, 18, p. 613, 1988 DOI: 10.1080/00397918808064019
Synthesis, p. 1081, 1984
Tetrahedron Letters, 32, p. 3243, 1991