Guide to the presentation of experimental data
The following information is a guide to the presentation of experimental data, including appropriate formats for citation.
In parentheses after the compound name (or its equivalent). Weight and percentage are separated by a comma – for example, the lactone (7.1 g, 56%).
In the form mp 75 °C (from EtOH) – that is, the crystallisation solvent in parentheses. If an identical mixed melting point is to be recorded, the form mp and mixed mp 75 °C is appropriate.
The units should be stated in the preamble to the Experimental section – for example, [α]D values are given in 10−1 deg cm2 g−1. Shown in the form [α]D 22–22.5 (c 0.95 in EtOH) – that is, concentration and solvent in parentheses.
Given in the form nD22 1.653.
In the presentation of elemental analyses, both forms (Found: C, 63.1; H, 5.4. C13H13NO4 requires C, 63.2; H, 5.3%) and (Found: C, 62.95; H, 5.4. Calc. for C13H13NO4: C, 63.2; H, 5.3%) are acceptable. Analyses are normally quoted to the nearest 0.1%, but a 5 in the second place of decimals is retained.
For identification purposes for new compounds, an accuracy to within ±0.3% is expected, and in exceptional cases, to within ±0.5% is required. If a molecular weight is to be included, the appropriate form is: [Found: C, 63.1; H, 5.4%; M (mass spectrum), 352 (or simply M+, 352). C13H13NO4 requires C, 63.2; H, 5.3%; M, 352].
These are given in the form λmax(EtOH)/nm 228 (ε/dm3 mol-1 cm-1 40 900), 262 (19 200) and 302 (11 500). Inflections and shoulders are specified as 228infl or 262sh. Alternatively the following form may be used: λmax (EtOH)/nm 228, 262 and 302 (ε/dm3 mol-1 cm-1 40 900, 19 200 and 11 500). log ε may be quoted instead of ε.
As follows: νmax/cm-1 3460 and 3330 (NH), 2200 (conj. CN), 1650 (CO) and 1620 (CN). The type of signal (s, w, vs, br) can be indicated by appended letters (for example 1760vs).
For all spectra δ values should be used, with the nucleus indicated by subscript if necessary (for example, δH, δC). A statement specifying the units of the coupling constants should be given in the preamble to the Experimental section – for example, J values are given in Hz. Instrument frequency, solvent, and standard should be specified. For example: δH(100 MHz; CDCl3; Me4Si) 2.3 (3 H, s, Me), 2.5 (3 H, s, COMe), 3.16 (3 H, s, NMe) and 7.3–7.6 (5 H, m, Ph).
A broad signal may be denoted by br, such as 2.43 (1 H, br s, NH). Order of citation in parentheses: (i) number of equivalent nuclei (by integration), (ii) multiplicity (s, d, t, q), (iii) coupling constant – for example, J1,2 2, JAB 4, (iv) assignment; italicisation can be used to specify the nuclei concerned (for example, CH3CH2). The proton attached to C-6 may be designated C(6)H or 6-H; the methyl attached to C-6, 6-Me or C(6)Me.
Mutually coupled protons in 1H NMR spectra must be quoted with precisely matching J values, in order to assist thorough interpretation. In instances of any ambiguities when taking readings from computer print-outs, mean J values should be quoted, rounded to the nearest decimal point.
Mass spectrometry data
Given in the form: m/z 183 (M+, 41%), 168 (38), 154 (9), 138 (31) etc. The molecular ion may be specified as shown if desired. Relative intensities in parentheses (% only included once). Other assignments may be included in the form m/z 152 (33, M − CH3CONH2). Metastable peaks may be listed as: M* 160 (189→174), 147 (176→161), etc. The type of spectrum (field desorption, electron impact, etc) should be indicated. Exact masses quoted for identification purposes should be accurate to within 5 ppm (EI and CI) or 10 ppm (FAB or LSIMS).
To avoid ambiguity, where magnetic couplings are reported, the Hamilton convention used should be included.