lignin ratio of MeO to C9

Lignin empirical formulae are based on ratios of methoxy groups to phenylpropanoid groups (MeO:C₉). The general empirical formula for lignin monomers is C₉H₁₀O₂ (OCH₃)_n, where n is the ratio of MeO to C9 groups. Where no experimental ratios have been found, they are estimated as follows: 0.94 for softwoods; 1.18 for grasses; 1.4 for hardwoods. These are averages of the lignin ratios found in the literature. Paper products, which are produced primarily from softwoods, are estimated to have an MeO:C9 ratio of 0.94.