Butylating agent

The acidic cleavage of the Boc group is most probably proceeded by the protonation of the carbamate carbonyl with subsequent elimination of isobutene, either by an open or, more likely, by a cyclic transition state. Protonation leads to the liberated anoine or the annmonium salt, respectively (Scheme 35). The byproduct isobutene is either protonated to give the stable carbenium ion, or generates the tcrt-butyl trifluoroacetate, both of which act as terf-butylating agents, especially, when nucleophilic amino acid side chains are present in the molecule (vide infra). 

Olah et al showed Nafion-H to be a very efficient de-r-butylation agent for aromatic compounds, and Rosevear and Wilshire have applied the trans-r-butylation reaction to the synthesis of a variety of ultraviolet absorbers of the general structure (40), as shown in Scheme 14. 

OSE As butylating agent in Organic synthesis, e.g., in the uuuiuf of butyl cellulose. 

In organic synthesis, butyl chloride is used as a butylating agent as well as an industrial solvent. 

Ravon et al. [93] found that zinc carboxylates exhibit an exceptionally high shape selectivity in a number of alkylation reactions. They studied catalysis on MOF-5, which is the archetype of a variety of MOFs with phenylenedicarboxylate-type ligands. This MOF structure consists of coordinatively saturated Zn O cluster units and completely complexed bdc ligands. However, MOF-5 exhibits catalytic activity in the Friedel-Crafts tert-butylation of toluene and biphenyl (tert-butyl chloride as a tert-butylating agent). Unlike the case of AICI3, mainly para-alkylation occurs on this catalyst, whereas ort/io-alkylation proceeds at a low rate. This indicates the occurrence of the process within the porous structure. 

Prepd. from various A-nitroso-A-butyl compds. Butylating agent. Used for esterifying amino acids for gc sepn. 

The above is a general procedure for preparing trialkyl orthophosphates. Similar yields are obtained for trimethyl phosphate, b.p. 62°/5 mm. triethyl phosphate, b.p. 75-5°/5 mm. tri-n-propyl phosphate, b.p. 107-5°/5 mm. tri-Mo-propyl phosphate, b.p. 83-5°/5 mm. tri-wo-butyl phosphate, b.p. 117°/5-5 mm. and tri- -amyl phosphate, b.p. 167-5°/5 mm. The alkyl phosphates are excellent alkylating agents for primary aromatic amines (see Section IV,41) they can also be ua for alkylating phenols (compare Sections IV,104-105). Trimethyl phosphate also finds application as a methylating agent for aliphatie alcohols (compare Section 111,58). 

Various 4-, 5-, or 4,5-disubstituted 2-aryIamino thiazoles (124), R, = QH4R with R = 0-, m-, or p-Me, HO C, Cl, Br, H N, NHAc, NR2, OH, OR, or OjN, were obtained by condensing the corresponding N-arylthiourea with chloroacetone (81, 86, 423), dichloroacetone (510, 618), phenacyichloride or its p-substituted methyl, f-butyl, n-dodecyl or undecyl (653), or 2-chlorocyclohexanone (653) (Method A) or with 2-butanone (423), acetophenone or its p-substituted derivatives (399, 439), ethyl acetate (400), ethyl acetyl propionate (621), a- or 3-unsaturated ketones (691), benzylidene acetone, furfurylidene acetone, and mesityl oxide in the presence of Btj or Ij as condensing agent (Method B) (Table 11-17). 

Osmate esters are fairly stable but are readily cleaved m the presence of an 0x1 dizing agent such as tert butyl hydroperoxide... 

Additives. Compounds are often added to the polymer at the extmder or melt homogenizer. Common additives are antioxidants (qv), thermal stabilizers, sHp agents, antiblock agents, anduv stabilizers. Popular antioxidants are 2,6-di-/-butyl-/)-cresol (BHT), octadecyl... 

With mercuric acetate (Hg(OOCCH2)2), olefins and / fZ-butyl hydroperoxide form organomercury-containing peroxides (66,100). The organomercury compound can be treated with bromine or a mild reducing agent, such as sodium borohydride, to remove the mercury. 

Rubber. The mbber industry consumes finely ground metallic selenium and Selenac (selenium diethyl dithiocarbamate, R. T. Vanderbilt). Both are used with natural mbber and styrene—butadiene mbber (SBR) to increase the rate of vulcanization and improve the aging and mechanical properties of sulfudess and low sulfur stocks. Selenac is also used as an accelerator in butyl mbber and as an activator for other types of accelerators, eg, thiazoles (see Rubber chemicals). Selenium compounds are useflil as antioxidants (qv), uv stabilizers, (qv), bonding agents, carbon black activators, and polymerization additives. Selenac improves the adhesion of polyester fibers to mbber. 

The solvent-free mono- -butyl, monoisopropyl bis-acetylacetone titanate, TYZOR AA95 [9728-09-9] is a Hquid at room temperature. By carefully controlling the mixture of alcohols used as solvent, a product, TYZOR GBA can be obtained, which is cold-storage-stable even in the presence of nucleating agents (96). 

---