Mercaptans tertiary

Esters ketones (sugars) 5. Mercaptans tertiary amines... 

Natural gas has no distinctive odour (except for very sour gases), and for safety reasons, pipeline companies and utilities commonly odorise the gas either as the gas enters the transmission system, or within local distribution zones. Various odorants may be used, the most common being mixtures of thiophenes and mercaptans. Tefiahydrothiophene (THT) is widely used throughout Europe and in the US (as Pennwall s odorant), whereas in the UK a cocktail of compounds is used comprising ethyl mercaptan, tertiary butyl mercaptan, and diethyl sulphide. 

If tertiary chlorine atoms are indeed critical to heat resistance, then reactions that consume them should improve polymer stabiUty. This is indeed the case. Post-reaction of polychloroprene with dodecyl mercaptan (111), use of higher levels of ethylene thiourea for curing (112), and inclusion of reactive thiols such as mercaptobenzimidazole in cure systems (113) all improve heat resistance. This latter technique is especially effective in improving the heat resistance of mercaptan modified polychloroprene. 

Dissociation extraction is the process of using chemical reac tion to force a solute to transfer from one liquid phase to another. One example is the use of a sodium hydroxide solution to extract phenolics, acids, or mercaptans from a hydrocarbon stream. The opposite transfer can be forced by adding an acid to a sodium phenate stream to spring the phenolic back to a free phenol that can be extrac ted into an organic solvent. Similarly, primary, secondary, and tertiary amines can be protonated with a strong acid to transfer the amine into a water solution, for example, as an amine hydrochloride salt. Conversely, a strong base can be added to convert the amine salt back to free base, which can be extracted into a solvent. This procedure is quite common in pharmaceutical production. 

Similar products are obtained from the photosensitized decomposition of the tertiary azides, suggesting that decomposition may result from the triplet azides under both direct and sensitized photolysis/461 Additional evidence for a discrete nitrene intermediate comes from the observation that this intermediate can be trapped by decomposition of the azides in the presence of good hydrogen donors such as tri- -butyItin hydride and jec-butyl mercaptan. Triarylamines result ... 

This one-step procedure is a convenient and general method for the preparation of carbamates. It is substantially simpler, quicker, and safer than the multistep methods hitherto used for the preparation of carbamates of tertiary alcohols. This procedure is applicable to the preparation of carbamates of primary, secondary, and tertiary alcohols and mercaptans, polyhydric alcohols, acetylenic alcohols, phenols, and oximes. It has also been extended to the preparation of carbamyl derivatives (i.e., ureas) of inert (non-basic) amines.10... 

Applications of these methods to various synthetic objectives have been reported the preparation of organosilicon-containing pseudothiuronium salts [66], mercaptans from alcohols [9, 67], 2-alkylpseudothiuronium picrates for the estimation of tertiary alcohols [68, 69], and alkylsulfonyl chlorides from pseudothioureas by chlorination of pseudothiourea-HCl salts [55]. (CAUTION May cause an explosion [70].)... 

Surprisingly it was reported that when potassium cyanate is substituted for sodium cyanate the yields of carbamates are reduced to less than 5 %. The reason for this drastic effect is not known at this time. In addition, the use of other alkali or alkaline metal cyanates in this reaction has not been investigated. The Loev [28] procedure appears applicable to the synthesis of carbamates from primary, secondary, and tertiary alcohols (2 hr reaction time affords 60-90% yields), cyclic and acyclic 1,3-diols, phenols, oximes, ald-oximes, and ketoximes, and primary, secondary, and tertiary mercaptans. Carbamates could not be obtained from diphenylethylcarbinol (dehydrated to 1,1-diphenylethylene) or trichloro- and trifluoromethylcarbinols. 

Secondary and tertiary mercaptans cleave at the a-carbon atom with loss of the largest group to give a prominent peak M - CH3, M - C2H5, M — C3H7,. . . . However, a peak at m/z 47 may also appear as a rearrangement peak of secondary and tertiary... 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

Saturated hydrocarbons Olefinic hydrocarbons Aromatic hydrocarbons Halocarbons Mercaptans Sulfides CS2 Ethers Ketones Aldehydes Esters Tertiary amines Nitro compounds (without a-H atoms) Nitriles (without a-atoms)... 

The direction of ring opening of nnsymmetnea) episulfides by thiols in the presence of either acid or base catalyst appears to be rather non-selective.1 Mixtures of primary and tertiary mercaptan have been obtained by reaction of isobutylene Bulfido with some of the simple aliphatic thiols such as -butanethiol in the presence of catalytic quantities of either boron trifluoride or sodium ethoxide (Eq. 43). 

Protection of alcohols.1 Dimethylthexylsilyl ethers are prepared from primary or secondary alcohols by reaction with 1 and either imidazole or N(C2H5)3 in DMF. The ethers of tertiary alcohols are prepared by reaction with dimethylthexylsilyl trifluoromethanesulfonate in the presence of lutidine or N(C2H5)3. Silylation of amines, amides, mercaptans, and acids is conducted under similar conditions. 

Reaction kinetics with the various reagents becomes faster as their nucleophilicity is increased. The following order of reactivity can be given primary aliphatic amine > primary aromatic amine > secondary aliphatic amine primary alcohol > secondary alcohol > water > tertiary alcohol phenol > mercaptan. 

High-boiling compounds with normal alkyl chains. Classes include alkanes, halides (Cl, Br, I), alcohols, mercaptans, ethers, sulfides, amines (primary, secondary, and tertiary), acetates, and cyanides. 

Odor is a sensation associated with smell, which can be hard to quantify. The same quantities of different materials cause different odor intensities. The unit of odor intensity (W) is based on the odor of tertiary butyl mercaptan or TBM (W = 1.0). Using that reference, H2S, for example, has an odor intensity of W = 0.08, or 8% of TBM. Most odorant substances contain sulfur. Table 3.31 lists a number of odorant substances and their relative odor intensities (W). 

TBM Tertiary butyl mercaptan 2-methyl 2-propanethiol (CH3)3CSH 1.00 (ref)... 

K. Potrafke, E. M. Read, R. E. et al (Exp. Stn., E. I. DuPont de Nemours and Co., Wilmington, Del.). J. Org. Chem. 1971, 36 (16), 2267-72 (Eng). Triarylimidazolyl free radicals oxidize electron-rich substances by rapid electron abstraction from tertiary amines, iodide ion, and metal ions and H atom abstraction from phenols, mercaptans, primary and secondary amines, and activated C-H compds. The rate consts. for electron abstraction from tertiary amines were related to s+ values via oxidn. potentials which were detd. by cyclic voltametry. 

An epoxy-polymercaptan reaction that is catalyzed with a tertiary amine is used in the standard two-component 5-min curing epoxy which can be found in the hardware stores. These fast-curing products, however, have a tendency to be somewhat brittle and may perform quite poorly under peel stress. The standard 5-min cure is obtained with the accelerated mercaptan, such as Capcure 3830-81 (Cognis Corporation). The fastest polymercaptan has a gel time of 40 s in a 25-g mass. 

The chemistry of epoxy/mercaptan systems involves the tertiary amine catalyst forming a salt with the mercaptan to generate a mercaptide anion, which is a strong nucleophile. The mercaptide will readily open the epoxy ring. Reaction with another mercaptan group can regenerate the mercaptide anion, as shown in Fig. 5.13. 

Thermal decomposition of methyl xanthates is similar to the pyrolysis of acetates for the formation of the double bond. Olefins are obtained from primary, secondary, and tertiary alcohols without extensive isomerization or structural rearrangement. The other products of the pyrolysis of the methyl xanthates are methyl mercaptan and carbon oxy-sulfide. The xanthates prepared from primary alcohols are more difficult to decompose than those prepared from secondary and tertiary alcohols. Over-all yields of 22-51% have been obtained for a number of tertiary alkyl derivatives of ethylene. Originally the xanthates were made by successive treatment of the alcohol with sodium or potassium, carbon disulfide, and methyl iodide. In a modification of this procedure sodium... 

These additions to the conjugated system are catalyzed by bases such as sodium hydroxide, sodium methoxide, tertiary amines, piperidine, and quaternary ammonium hydroxides. Cupric acetate catalyst is used in the conversion of acrolein to /S-methylmercaptopropionaldehyde, CHjSCHjCHjCHO (84%). The addition of mercaptans is analogous to the addition of alcohols to these systems (method 121). However, the thiol group is more active than the hydroxyl group, as is shown by... 

Sodium sulfhydride (NaSH) is a much better reagent for the formation of thiols (mercaptans) from alkyl halides than H2S and is used much more often. It is easily prepared by bubbling H2S into an alkaline solution, but hydrosulfide on a supported polymer resin has also been used. " The reaction is most useful for primary halides. Secondary substrates give much lower yields, and the reaction fails completely for tertiary halides because elimination predominates. Sulfuric and sulfonic esters can be used instead of halides. Thioethers (RSR) are often side products. The conversion can also be accomplished under neutral conditions by treatment of a primary halide with F and a tin sulfide, such as PhsSnSSnPhs. An indirect method for the preparation of a thiol is the reaction of an alkyl halide with thiourea to give an isothiuronium salt (119), and subsequent treatment with alkali or a... 

The flash photolysis of hexaarylbiimidazole produces imidazolyl radicals " which have been shown to be more nearly planar than the parent dimers ort/io-substituents in the aryl rings decrease the radical stability. The radicals oxidize electron-rich substrates by rapid electron abstraction from tertiary amines, iodide, and metal ions, and by hydrogen abstraction from phenols, mercaptans, secondary amines, and active methylene com-pounds." " Studies have been made of the photooxidation of /euco-triphenyl-methane dyes by these radicals." " ... 

The reaction is catalysed by an organic base, usually an amine, which in the past has nearly always been the tertiary amine 2,4,6-tri(dimethyl aminomethyl) phenol. Such LP-modified epoxy resins have been in existence for more than 30 years. Their popularity declined because of the mercaptan odour of the polysulphide polymers in the uncured state and because of the use of a tertiary aromatic amine. 

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