Petroleum benzine is a hydrocarbon-based solvent mixture that is classified by its physical properties rather than a specific chemical composition, often obfuscating distinction within the long list ofpetroleum distillate solvent mixtures: mineral spirits, naphtha, white spirits, petroleum spirits, turps substitute, mineral turpentine, petroleum benzine, petroleum ether, ligroin, and Stoddard Solvent. The chemical composition of a petroleum distillate can also be modified to afford a solvent with reduced concentration of unsaturated hydrocarbons, i.e. alkenes, by hydrotreating and/or reduced aromatics, e.g.benzene, toluenexylene, by several dearomatization methods. In a document that attempts to draw more concise distinctions between hydrocarbon solvents, conservator Alan Phenix explains that the most important distinction amongst the various hydrocarbon solvents are their boiling/distillation ranges and aromatic content. Given the toxicity/carcinogenicity of some aromatic hydrocarbons, most notably benzene, the aromatic content of petroleum distillate solvents, which would normally be in the 10-25% range for most petroleum fractions, can be advantageously reduced when their special solvation properties are not required and a less odorous, lower toxicity solvent is desired, especially when present in consumer products. Phenix further points out that "To all intents and purposes petroleum benzine appears synonymous with petroleum spirit." Petroleum spirit is generally considered to be the fractions between the very lightest hydrocarbons, petroleum ether, and the heavier distillates, mineral spirits. For example, petroleum benzine with a boiling range of 36 - 83 °C sold by EMD Millipore under CAS-No. 64742-49-0 is identified in the product MSDS as hydrotreated light petroleum distillates comprising ≥ 90% C5-C7 hydrocarbons, n-alkanes, isoalkanes, and < 5% n-hexane, while Santa Cruz Biotechnology sells a petroleum ether product under the same CAS-No. Fisher Scientific offers a product ‘Benzine ' that retails for a high price that would suggest it is a speciality product but in fact conforms to Marathon Petroleum's 'VM&P Naphtha' found widely distributed in many hardware stores in North America. According to their corresponding MSDS, most commercially offered petroleum benzine solvents consist of parrafins with chain lengths of C5 to C9, cycloparaffins and aromatic hydrocarbons. The TSCA Definition 2008 describes petroleum benzine as "a complex combination of hydrocarbons obtained by treating a petroleum fraction with hydrogen in the presence of a catalyst. It consists of hydrocarbons having carbon numbers predominantly in the range of C4 through C11 and boiling in the range of approximately -20°C to 190°C."
Health concerns
Beginning in the 1960s and 70's, the high incidence rate of polyneuropathy amongst industrial workers chronically exposed to petroleum benzine and other hydrocarbon solvents prompted investigations into the safety of chronic exposure to petroleum distillates. Many of the cases of polyneuropathy amongst workers chronically exposed to vapors of petroleum benzine and similar solvents have been attributed to the n-hexane component of these mixtures. Using an animal model, Ono and coworkers reported that chronic exposure to hydrocarbon solvent vapors conspicuously impaired peripheral nerve function in the 500 ppm n-hexane group, slightly impaired in the 200 ppm n-hexane group and petroleum benzine II group, and barely impaired in the petroleum benzine I group. These results suggest that some components in petroleum benzine are likely to antagonize the neurotoxic effects of n-hexane to the peripheral nerves, possibly by inhibiting the oxidation of n-hexane to its more toxic metabolites 2-hexanone and 2,5-hexanedione. Ono and coworkers also observed depressed body weight gains amongst the exposed groups compared to the control group in the order: petroleum benzine II > petroleum benzine I >> 500 ppm n-hexane > 200 ppm n-hexane. These results suggest that other components found in petroleum benzine may have an additive, syngeristic or potentiative effects on the biological effects of n-hexane. Namely, 1000 ppm n-hexane, 3000 ppm n-heptane and 1000 ppm toluene were reported to have the effect of depressing the body weight gain of rats.
