We report a computer simulation study of four 1,n-diols (1,2-ethanediol to 1,5-pentanediol). It is found that increasing the alkyl chain length increases chain-like clusters, and correspondingly the structure factor pre-peak, just like for mono-ols. However, our calculated X-ray intensities show that the pre-peak tends to diminish to a shoulder, in contrast with mono-ols where the pre-peak becomes more apparent with increasing alkyl chain. We attribute this contrasting finding to the fact that the alkyl chain is constrained between the two hydroxyl groups in linear diols, while they are free in linear mono-ols. (C) 2017 Elsevier B.V. All rights reserved.