Water solubility carbamates

This group was developed as a water soluble carbamate in peptide synthesis. It is prepared hy methylating (2-phenylthio)ethylcarbamates of amino acids with methyl iodide and AgBp4. Amines may also be protected using Pms-4-nitrophenyl carbonate as a stable crystalline reagent that can be stored. The Pms group was cleavable with NaHCOi, hut Na2C03 was proved to be more efficient. ... 

Salt formation with Brmnsted and Lewis acids and exhaustive alkylation to form quaternary ammonium cations are part of the rich derivati2ation chemistry of these amines. Carbamates and thiocarbamates are formed with CO2 and CS2, respectively the former precipitate from neat amine as carbamate salts but are highly water soluble. 

Benzyloxycarbonyloxy)phenyl]dimethylsulfonium methyl sulfate, NaOH, H20,51-95% yield. " This is a water-soluble reagent for benzyloxy carbamate formation. Analogous reagents for the introduction of BOC and Fmoc were also prepared and give the respective derivatives in similar high yields. 

A solution of 32 g (030 mol) phosgene in 200 ml benzene is added dropwise at 30°C to a stirred soiution of 53.5 g (032 mol) 3-o-toloxy-13-Pfopanediol in 400 ml benzene. The mixture is stirred for an hour after the addition is completed, and a solution of 39 g of dl-methylaniline in 100 ml benzene is then added, and stirring continued for a half-hour. Ice water (about one-third volume) is then added, and the benzene layer formed is separated and stirred with 500 ml concentrated ammonia at 5°Cfor six hours. The precipitated solid (weighing about 55 g) is recovered and recrystallized from water. The product thus obtained in a yield of about 53 g is 3-(o-toloxy)-2-hydroxypropyl carbamate it is a crystalline solid melting at about 93°C, and having a lower water-solubility and higher oil-solubility than 3-o-toloxy-13-propanediol. 

Lippi et. al (87) and Dirstine (88) circumvented titration by converting the liberated fatty acids into copper salts, which after extraction in chloroform are reacted with diethyldithio-carbamate to form a colored complex which is measured photometrically. While the end point appears to be more sensitive than the pH end point determination, the advantages are outweighed by the additional steps of solvent extraction, centrifugation and incomplete extraction when low concentrations of copper salts are present. Other substrates used for the measurement of lipase activity have been tributyrin ( ), phenyl laurate (90), p-nit ro-pheny1-stearate and 3-naphthyl laurate (91). It has been shown that these substrates are hydrolyzed by esterases and thus lack specificity for lipase. Studies on patients with pancreatitis indicate olive oil emulsion is definitely superior to water soluble esters as substrates for measuring serum lipase activity. 

Acidic compounds with N—H bonds such as amides, carbamates, and hydan-toins, may be transformed to /V-rnannich bases to form oral prodrugs [2], These prodrugs are generally made by reacting an amide, carbamate, or hydantoin with formaldehyde and a primary or secondary aliphatic or aromatic amine (Fig. 4). The (V-mannich prodrugs tend to have better physicochemical properties than the parent compounds. The derivatives may have increased water solubility, dissolution rate, and/or lipophilicity. 

Boublik, T., Fried, V., Hala, E. (1984) The Vapor Pressure of Pure Substances, 2nd revised Edition, Elsevier, Amsterdam, The Netherlands. Bowman, B. T., Sans, W. W. (1983) Determination of octanol-water partitioning coefficient (KqW) of 61 organophosphorus and carbamate insecticides and their relationship to respective water solubility (S) values. J. Environ. Sci. Health B18, 667-683. Bradley, R. S., Cleasby, T. G. (1953) The vapour pressure and lattice energy of some aromatic ring compounds. J. Chem. Soc. 1953, 1690-1692. 

Only a limited amount of water is added at this point because /-butyl carbamate has some solubility in the resulting aqueous slurry. With water-insoluble carbamates the amount of water added is immaterial. 

Bowman BT, Sans WW. 1983. Determination of octanol-water partitioning coefficients (Kow) of 61 organophosphorus and carbamate insecticides and their relationship to respective water solubility (S) values. J Environ Sci Health [B] 13 667-633. 

Phenylcarbamates, or carbanilates, generally exhibit low water solubilities, and thus they are almost immobile in soil systems. Chlorpropham and Propham are readily volatilized from soil systems, but Terbutol and Carbaryl (Fig. 10, Table 3) are not. Ester- and amide-hydrolysis, N-dealkylation and hydroxylation are among the chemical reactions that carbamates undergo. The N-methylcar-bamate insecticides (Fig. 10, Table 3) commonly used in soils are Carbaryl, Methiocarb,Aldicarb,and Carbofuran [74,173]. 

Turning our attention first to alkyl carbamates of cyclic amides, we find interesting attempts to improve the pharmaceutical and pharmacokinetic properties of 5-fluorouracil (8.152, R = H) [194-196], This antitumor agent, while clinically useful, suffers from poor water solubility, unsatisfactory delivery properties and low tissue selectivity. A variety of prodrug candidates were prepared, in particular the alkyl and aryl carbamates presented in Table 8.12. With the exception of the more-lipophilic derivatives, these compounds exhibited somewhat improved water solubility. More importantly, both rectal and oral bioavailability were markedly improved. The activation... 

M. Safadi, R. Oliyai, V. J. Stella, Phosphoryloxymethyl Carbamates and Carbonates -Novel Water-Soluble Prodrugs for Amines and Hindered Alcohols , Pharm. Res. 1993, 10, 1350-1355. 

Chemical/Physical Forms water-soluble salts (Hartley and Kidd, 1987). When heated to 75 °C, asulam decomposed to sulfanilic acid, carbamic acid, and sulfanilamide. At 90 °C, 4-nitro- and 4-nitrosobenzene sulfonic acids were released (Rajagopal et al., 1984). 

Oxamyl. Oxamyl Is an oxime carbamate with a 280,000 ppm water solubility (63) and a 2,3 x 10 torr vapor pressure (19). It Is used as an Insectlclde/nematlclde. 

This theory of charge repulsion could explain why K(,(.s for slmazlne and atrazlne, and likely other trlazlnes, are so much lower than that predicted by their water solubilities. The same theory may apply to other classes of compounds, such as carbamates and aromatic acids further Investigation Is warranted. 

Uncharged carbamates, such as carbaryl (8.20, sevin), can penetrate the CNS of insects (which do not use AChE in their neuromuscular junction) and they act quite selectively as insecticides with a low toxicity to mammals (median lethal dose [LDjg] in the rat = 540 mg/kg, p.o.). Many useful insecticides can thus be found in this group. Malathion (8.21) is a pro-drug, since the thiophosphate must be bioactivated to the phosphate form—a transformation carried out by insects but not mammals. Additionally, the ester groups of malathion are rapidly hydrolyzed in higher organisms to water-soluble and... 

Organophosphorus compounds and carbamates, in contrast to chlorinated hydrocarbons, readily decompose to water-soluble components and so do not act over extended periods of time. Their immediate toxicity to both insects and animals is much greater than that of chlorinated hydrocarbons, however. Added safety precautions are required during the application of both organophosphates and carbamates, especially because of their toxicity to honeybees (Figure 15.19). 

Bowman and Sans [12] measured Kow and water solubilities at 20°C for liquid and solid carbamates and organophosphorous insecticides and related compounds. Based on these data, they derived the following equation ... 

Bowman, B. T., and W. W. Sans, Determination of Octanol-Water Partitioning Coefficients (KOW) of 61 Organophosphorus and Carbamate Insecticides and Their Relationship to Respective Water Solubility (5) Values. J. Environ. Sci. Health, 1983 B18(6), 667-683. 

Tables 1 and 2 show the chemical name, molecular formula, water solubility, and vapor pressure of representative carbamate and urea pesticides.

In comparison with OC pesticides, the current-use OP and carbamate pesticides are relatively more water soluble and less bioaccumulative. However, because of the high volume of their usage, there is a potential for these compounds to be present in the environment. Herbicides such as atrazine, metolachlor, and alachlor have been surveyed in the Great Lakes [59] and along the margins of fields, streams, and tributaries within the Great Lakes Basin [5,60]. 

First, mobile phase and column we saw that most of the small molecule separations could be made on a C18 column in An/buffer water, with the exception of charged molecules and carbohydrates, which are too water soluble. We saw a range of polarity from fat-soluble vitamins, steroids, triglycerides, chlorinated pesticides eluting in 60-80% An/water, to carbamate, phosphate pesticides, anticonvulsants, antidepressants at 40-50% An/water, to nucleosides, nucleotides, aspirin, and water-soluble vitamins at 5-10% An/water. If you know something about the compound s structure or its solubility, you have a good clue as to what mobile phase can be used for its separation. 

Synonyms isocyanic acid methyl ester, isocyanatomethane, MIC Formula CH3NCO MW 57.05 CAS [624-83-9] used in the manufacture of carbamate pesticides colorless liquid with an unpleasant odor boils at 39°C freezes at -80°C vapor pressure 400 torr at 20°C density 0.96 g/mL at 20°C vapor density 1.97 (air= 1) decomposes in water soluble in most organic solvents highly toxic and flammable. 

These drugs include alcohols (ethchlorvynol, chloral hydrate), piperidinediones (glutethimide, methyprylon), and carbamates (meprobamate). They are rarely used in therapy, though the low cost of chloral hydrate makes it attractive for institutional use. Little is known about their molecular mechanisms of action. Most of these drugs are biotransformed to more water-soluble compounds by hepatic enzymes. Trichloroethanol is the pharmacologically active metabolite of chloral hydrate and has a half-life of 6-10 hours. However, its toxic metabolite, trichloroacetic acid, is cleared very slowly and can accumulate with the nightly administration of chloral hydrate. 

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