Mercaptoethylamine

The ester formed above is heated under reflux for 9 hours with 50 ml. of 48% aqueous hydrobromic acid. The reaction mixture is dissolved in 250 ml. of hot water and allowed to cool overnight. The precipitated benzoic acid is removed by filtration, and the filtrate is evaporated to dryness under reduced pressure. The solid residue is dissolved in 50 ml. of hot water, and the solution is brought to pH 6 (isoelectric point for leucine) with 6 J T ammonium hydroxide solution, after which 200 ml. of 95% ethanol is added. Cooling in the refrigerator for 36 hours allows precipitation of the amino acid. The yield is 6.3 g., or 78%. The product may be recrystallized from a mixture of water and ethanol. 

The amino acids listed below are prepared in similar manner by reaction of the proper organic halide with benzamidomalonic ester (p. 145). The halides used and the yields of dl-amino acid obtained are given in parentheses phenylalanine (benzyl chloride, 90%) aspartic acid (ethyl chloroacetate, 62%) and valine (isopropyl iodide, 71%). 

A stream of dry hydrogen sulfide is passed into 200 ml. of absolute ethanol (p. 142) with rapid stirring and cooling in an ice bath, while a solution of 91.1 g. (2.1 moles) of ethyleneimine (p. 153) (Caution— toxic material) in 819 ml. of absolute ethanol is added dropwise (3-4 hours). (Hood.) The solution is evaporated under reduced pressure and an inert atmosphere until the volume is 50-75 ml. The precipitated white solid is filtered off, dried, washed with petroleum 

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Reaction with Sulfur Nucleophiles, Because sulfai is highly nucleophilic, reactions of aziridines with sulfur nucleophiles generally proceed rapidly (111) and with good yields. The reaction of hydrogen sulfide [7783-06S-J with ethyleneimine yields cysteamine [60-23-1] (2-mercaptoethylamine) or bis(2-aminoethyl)sulfide [871-76-1] (2,112) depending on the molar ratio of the reactants. The use of NaHS for the synthesis of cysteamine has also been described (113). 

Primary and secondary aliphatic and aromatic amines react readily with thiiranes to give 2-mercaptoethylamine derivatives (Scheme 76) (76RCR25, 66CRV297). The reaction fails or gives poor yields with amines which are sterically hindered e.g. N,iV-dicyclohexylamine) or whose nitrogen atom is weakly basic e.g. N,A/ -diphenylamine). Aromatic amines are less reactive and higher reaction temperatures are usually required for them. The reaction mechanism is Sn2 and substituted thiiranes are attacked preferentially at the least hindered... 

Aromatic aldehydes such as benzaldehyde, anisaldehyde, or 4-pyridinealdehyde react with neat N,S-silylated 2-mercaptoethylamines 475 at 20°C to give the N,S-... 

The crystal and molecular structure of the Ni11 complex of the simplest amino-thiolate ligand 2-mercaptoethylamine (aet) (454) has been determined and shows that the complex, contrary to earlier belief, has a trans configuration.1277... 

The use of a 500-fold molar excess of 2-mercaptoethylamine over the concentration of antibody presence was found to result in a partially reduced antibody in which two disulfides were reduced to yield four thiols (Sun et al., 2005). This strategy can be used to retain a biospecific antibody construct for subsequent discrete conjugation at the hinge region between the heavy chains. 

Figure 1.77 Disulfide reducing agents such as 2-mercaptoethylamine can be used to cleave the disulfide bonds in the hinge region of antibody molecules. Either intact IgG molecules or F(ab )2 fragments may be reduced in this manner to yield monofunctional antigen binding fragments.

Purify the reduced IgG from excess 2-mercaptoethylamine and reaction by-products by dialysis or gel filtration using a desalting resin. All buffers should contain 1-10 mM EDTA to preserve the free sulfhydryls from metal-catalyzed oxidation. The sulfhydryl-containing half antibody now may be used in conjugation protocols that use —SH-reactive heterobifunctional crosslinkers (Chapter 5, Section 1). 

Figure 22.30 An iodoacetamide derivative of PE containing an extended spacer arm can be constructed through a carbodiimide coupling of iodoacetic acid to PE, followed by reaction with 2-mercaptoethylamine, and finally another reaction with iodoacetate.

For reduction of the cystamine disulfides, add 20 pi of 1.0 M DTT and incubate at room temperature for 15 minutes. This will release 2-mercaptoethylamine from the cystamine modification site and create the free sulfhydryl on the 5 terminus of the oligonucleotide. 

CdS CdF2, Cd(C104)2, CdCl2, Cdl2, Cd(CH3COO)2, Cd(HCOO)2 + 2-mercaptoethylamine hydrochloride, cysteine, ethylenediamine, triethanolamine, monoethanolamine, nitrilotriacetic acid trisodium salt Na2S XRD, UV, AFM, Auger, XPS 77,78... 

Semitelechelic HPMA polymers were synthesized by free radical polymerization of HPMA using 2,2 -azobis(isobutyronitrile) (AIBN) as the initiator and alkyl mercaptans as chain transfer agents. Alkyl mercaptans with different functional groups, namely, 2-mercaptoethylamine, 3-mercapto-propionic acid, 3-mercaptopropionic hydrazide, and methyl 3-mercapto-propionate, were used as the chain transfer agents ST HPMA polymers... 

Figure 1 The effect of concentration ratio of mercaptans ( , 2-mercaptoethylamine , methyl 3-mercaptopropionate , 3-mercaptopropionic acid , 3-mercaptopropionic hydrazide) to HPMA on the weight average molecular weight (SEC) of ST HPMA polymers (data from Reference [20]). 

Exchange of the 5-H of uridine (72, Ri = H, Rg = OH, R3 = H, X = 0) in slightly basic D2O at 60° using 2-mercaptoethylamine as base has been reported. Similar exchange was also observed in deoxyuridine (72, Ri=R2 = Rs = H, X = 0) and uridine monophosphate (72, Ri = H, R2 = OH, R3 = PO3H2, X = 0), and a probable mechanism involves a Michael 1,4-addition across the double bond followed by a tautomeric shift and then elimination of the C-5 hydrogen and the nucleophile. Exchange of the 6-H or uridine in the presence of ammonium sulfite at 37° proceeds best at pH 9. The mechanism involves deprotonation of the bisulfite-uridine complex by the ammonia or added amines. ... 

This is a complex molecule, made up of an adenine nucleotide (ADP-3 -phosphate), pantothenic acid (vitamin B5), and cysteamine (2-mercaptoethylamine), but for mechanism purposes can be thought of as a simple thiol, HSCoA. Pre-eminent amongst the biochemical thioesters is the thioester of acetic acid, acetyl-coenzyme A (acetyl-CoA). This compound plays a key role in the biosynthesis and metabolism of fatty acids (see Sections 15.4 and 15.5), as well as being a building block for the biosynthesis of a wide range of natural products, such as phenols and macrolide antibiotics (see Box 10.4). 

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