Aliphatic, toxicity

F. L. M. Pattison, Toxic Aliphatic Fluorine Compounds, Elsevier Publishing Co., New York, 1959, p. 16. 

Polyfunctional aliphatic resins have exhibited high reactivity and degrees of cure with amines but problems of toxicity have diminished their usehilness and commercial interest. SoHd epoxy resins can be prepared by the taffy process or the advancement process. 

Propionates and higher aliphatic esters generally become less toxic as the si2e of the alkyl carboxylate increases. As an example, the LD q (rat, oral) for ethyl nonanoate [123-29-5] is greater than 43 g/kg, and the LD q (rat, oral) for ethyl heptanoate [106-30-9] is 34.6 g/kg. 

Toxic chemicals can enter the body in various ways, in particular by swallowing, inhalation and skin absorption. Skin absorption may lead to dermatitis and this can be a most annoying complaint. Whereas some chemicals may have an almost universal effect on human beings, others may attack only a few persons. A person who has worked with a given chemical for some years may suddenly become sensitised to it and from then on be unable to withstand the slightest trace of that material in the atmosphere. He may as a result also be sensitised not only to the specific chemical that caused the initial trouble but to a host of related products. Unfortunately a number of chemicals used in the plastics industry have a tendency to be dermatitic, including certain halogenated aromatic materials, formaldehyde and aliphatic amines. 

Aliphatic and cycloaliphatic amine curing agents irritants, sensitizers, corrosive, absorbed through skin, respiratory irritants high toxicity... 

The mechanism of this reaction has been studied by several groups [133,174-177]. The consensus is that interaction of ester with the phenolic resole leads to a quinone methide at relatively low temperature. The quinone methide then reacts rapidly leading to cure. Scheme 11 shows the mechanism that we believe is operative. This mechanism is also supported by the work of Lemon, Murray, and Conner. It is challenged by Pizzi et al. Murray has made the most complete study available in the literature [133]. Ester accelerators include cyclic esters (such as y-butyrolactone and propylene carbonate), aliphatic esters (especially methyl formate and triacetin), aromatic esters (phthalates) and phenolic-resin esters [178]. Carbamates give analogous results but may raise toxicity concerns not usually seen with esters. 

Because osmium tetroxide is expensive, and its vapors are toxic, alternate methods have been explored for effecting vic-glycol formation. In the aliphatic series, olefins can be hydroxylated with hydrogen peroxide with the use of only a catalytic amount of osmium tetroxide. Anhydrous conditions are not necessary 30% hydrogen peroxide in acetone or acetone-ether is satisfactory. The intermediate osmate ester is presumably cleaved by peroxide to the glycol with regeneration of osmium tetroxide. When this reaction was tried on a A -steroid, the product isolated was the 20-ketone ... 

The Schmidt reaction of ketones works best with aliphatic and alicyclic ketones alkyl aryl ketones and diaryl ketones are considerably less reactive. The reaction is only seldom applied to aldehydes as starting materials. The hydrazoic acid used as reagent is usually prepared in situ by treatment of sodium azide with sulfuric acid. Hydrazoic acid is highly toxic, and can detonate upon contact with hot laboratory equipment. 

Toxicity, Similar to NG Uses. This substance, as well as other aliphatic compds such as nitroisobutylglycol dinitrate, comprising a branched chain hydrocarbon to which one nitro and two nitrate groups are attached, has been proposed by Bergeim (Ref... 

Following are some props of methyl nitrate-methanol mixts vel of deton ranging from 2400—4900 to 7500—8200m/sec, gas vol about 8732/kg, Qe 1640—1700kcal/kg, power and brisance — comparable to those of NG, sensitivity to shock — comparable to that of DNB, and toxicity — comparable to that of aliphatic... 

AnUine, however, is too toxic for use in mbber products. Its less toxic reaction product with carbondisulfide, thiocarbanihde, was introduced as an accelerator in 1907. Further developments led to guanidine accelerator [4]. Reaction products formed between carbon disulfide and aliphatic amines (dithiocarbamates) were first used as accelerators in 1919 [5]. These were and still are the most active accelerators in respect to both cross-finking rates and extent of cross-link formation. However, most dithiocarbamates accelerators give little or no scorch resistance and therefore cannot be used in aU applications. 

In 1868 two Scottish scientists, Crum Brown and Fraser [4] recognized that a relation exists between the physiological action of a substance and its chemical composition and constitution. That recognition was in effect the birth of the science that has come to be known as quantitative structure-activity relationship (QSAR) studies a QSAR is a mathematical equation that relates a biological or other property to structural and/or physicochemical properties of a series of (usually) related compounds. Shortly afterwards, Richardson [5] showed that the narcotic effect of primary aliphatic alcohols varied with their molecular weight, and in 1893 Richet [6] observed that the toxicities of a variety of simple polar chemicals such as alcohols, ethers, and ketones were inversely correlated with their aqueous solubilities. Probably the best known of the very early work in the field was that of Overton [7] and Meyer [8], who found that the narcotic effect of simple chemicals increased with their oil-water partition coefficient and postulated that this reflected the partitioning of a chemical between the aqueous exobiophase and a lipophilic receptor. This, as it turned out, was most prescient, for about 70% of published QSARs contain a term relating to partition coefficient [9]. 

Bonse G, Henschler D. 1976. Chemical reactivity, biotransformations and toxicity of polychlorinated aliphatic compounds. CRC Crit Rev Toxicol 10 395-409. 

Cornish HH and Adefuin J. 1966. Ethanol potentiation of halogenated aliphatic solvent toxicity. Amind Hyg Assoc J 27 57-61. 

Reduction of carbonyl groups Terpene and aromatic aldehydes (lOOppm) were reduced by microalgae. In a series of chlorinated benzaldehyde, m - or p-chlorobenzaldehyde reacted faster than the o-derivative. Due to toxicity, the substrate concentrations are difficult to increase. Asymmetric reductions of ketones by microalgae were reported. Thus, aliphatic " and aromatic " ketones were reduced. 

Grosjean D (1991) Atmospheric chemistry of toxic contaminants. 4. Saturated halogenated aliphatics methyl bromide, epichlorhydrin, phosgene. J Air Waste Manage Assoc 41 56-61. 

Croni MT et al. (2000) Structure-toxicity relationships for aliphatic compounds encompassing a variety of mechanisms of toxic action to Vibrio fischeri. SAR QSAR Environ Res 11(3-4) 301-312... 

Monofluoroacetic acid offers little promise as a mosquito larvicide, but 2-ethylhexyl monofluoroacetate is a very powerful aphicide. The high toxicity of the fluorinated lower aliphatic acids and their esters to vertebrates probably precludes their use as insecticides except under highly controlled conditions. The toxicity of the fluorinated acids to the vertebrates is attributed to their interference with an enzyme system, but the possibility of finding one with a high specificity for insects is not excluded. 

The behavior of the different amines depends on at least four factors basicity, nucleophilicity, steric hindrance and solvation. In the literature (16), 126 aliphatic and aromatic amines have been classified by a statistical analysis of the data for the following parameters molar mass (mm), refractive index (nD), density (d), boiling point (bp), molar volume, and pKa. On such a premise, a Cartesian co-ordinate graph places the amines in four quadrants (16). In our preliminary tests, amines representative of each quadrant have been investigated, and chosen by consideration of their toxicity, commercial availability and price (Table 1). 

Phenol is an important chemical, from the point of its industrial and commercial applications, but is of great environmental apprehension due to its toxicity. Its chemical name is hydroxybenzene which is more acidic compared to aliphatic alcohols hence is also known as carbolic acid [4]. At ambient temperature and pressure it is a hygroscopic crystalline solid, which is colourless when pure [5] but... 

If the homopolymer decomposes at the fabrication temperature another approach is to make a copolymer that can be melt processed at a lower temperature. For example, polyhydroxybutyrate decomposes at the processing temperature (190°C), whereas the copolymer with valeric acid can be processed at 160°C without decomposition. These aliphatic polyesters are biodegradable and most importantly, the decomposition products are not toxic, hence their use in medical applications (e.g., sutures). 

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