Abstract
The exploratory analysis of the differences between preprints and the corresponding peer reviewed journal articles for ten studies first published on ChemRxiv and on Preprints suggests outcomes of relevance for chemistry researchers and educators. The full transition to open science requires to undertake new educational work of doctoral students and young researchers on scholarly communication in the digital age. Learning that preprints differ only slightly in comparison to peer reviewed journal articles for all the basic sciences further supports the widespread adoption of preprints amid research chemists.

Introduction

Publishing scientific articles in the form of “preprints” (though most preprints will never have a print version [1]), namely of freely accessible scientific documents posted on the internet before the peer review process, is rapidly replacing the conventional publishing process. For instance, the publication rate of arxiv.org (arXiv), a website managed by the Library of Cornell University, in 2019 approached 13,000 preprints per month (12,989/month) [2]. Originally aim ed at physics, mathematics and computer science scholars, the platform currently hosts works also from quantitative biology, quantitative finance, statistics, electrical engineering, systems science, and economics scholars. Similarly, the number of papers published by biorxiv.org (bioRxiv), a preprint repository for the life sciences managed by Cold Springer Harbor Laboratory since late 2013, in October 2020 exceeded the 100,000 threshold, with a publication rate of 2,943 preprints/month in the first 8 months of 2020 [3].
In slightly more than three years since its debut in May 2016 preprints.org (Preprints), the multidisciplinary preprint platform owned by the scientific publisher MDPI, reached the milestone of 10,000 preprints [4]. Yet, it took only 13 months to almost double the number of preprints to 17,000 by late October 2020. Showing the global impact of preprints, the latter studies at Preprints were co-authored by over 64,000 authors, whereas those at bioRxiv from close to 424,000 scholars.
We briefly remind that, in general, prior to publication of the preprint an editor working for the organisation owning the preprint server checks the uploaded manuscripts for minimum quality and lack of plagiarism. Eventually, the manuscript authored with no requirements on how to write and structure the article is posted online as PDF (portable document format) file.
Dubbed Chemistry Preprint Server (CPS), the first chemistry preprint server was launched online in August 2000 at http://preprint.chemweb.com. Two years later the CPS hosted already 500 preprints in numerous areas of chemistry, from biochemistry to computational chemistry [5], co-authored by scholars based in 51 different countries. Alas, the website chemweb.com was subsequently closed because “changes in search algorithms resulted in a dramatic decline in traffic and a corresponding drop in revenue” [6]. Other attempts to launch chemistry preprint servers from large publishing companies were unsuccessful [7]. Publishing in the most oligopolistic sector of the highly profitable scientific publishing industry [8], chemistry scholars were recently found to be those publishing with the lowest frequency in open access (OA) journals. In detail, the analysis of 100,000 recent articles from all disciplines found that less than 20% of the chemistry papers were freely accessible [9].
In August 2017 the American Chemical Society joined by the Royal Society of Chemistry and the German Chemical Society launched a new chemistry preprint server at chemrxiv.org (ChemRxiv, today partly owned also by the Chemical Societies of Japan and of China). By late October 2020, the platform hosted 6,422 preprints, with an average publication rate of 324 preprints/month recorded in the first 8 months of 2020 [10]. By the same time, Preprints hosted close to 1,000 chemistry preprints.
Getting back to arXiv, a study published in 2016 comparing more than 12,000 preprints with the corresponding refereed journal, concluded that little differences exist between the preprint and peer reviewed articles when considering titles, abstracts and the body of the text (both on the semantic and on the editorial level) [11]. Similarly, extending the same statistical analysis to 2,500 preprints from bioRxiv revealed very little changes between the final published scientific papers and their preprint versions [12]. Focusing the analysis on a few (56) preprints published by bioRxiv in 2016, the preprints were found to be generally similar to the peer reviewed final published articles [13]. The following exploratory analysis looks at the differences between preprints and the corresponding peer reviewed journal articles for 10 studies first published as preprints in ChemRxiv and in Preprints. The outcomes are relevant for both chemistry researchers and educators.

Methodology

Ten preprints which underwent subsequent publication as peer reviewed articles in international scientific journals were selected, five from ChemRxiv (Table 1) and five from Preprints (Table 2).
Table 1 . Selected ChemRxiv preprints and journal hosting the peer reviewed article.