Evaluation of Initiators and Fillers in Diallyl Phthalate Resins by Differential Scanning Calorimetry

Seven organic peroxide initiators for the polymerization of diallyl-o-phthalate prepolymers were studied using differential scanning calorimetry. Included were t-butyl perbenzoate, dicumyl peroxide, α,α′-bis(t-butyl peroxy) diisopropyl-benzene, 2,5-dimethyl-2,5-di(t-butyl peroxy) hexane, 2,5-dimethyl-2,5-di(t-butyl peroxy)hexyne-3, di-t-butyl peroxide, and t-butyl hydroperoxide. Heats of reaction and reaction rate constants are presented for each initiator at 1, 2, 3, and 4 phr of diallyl-o-phthalate prepolymers. The differences in reaction temperature and rate are discussed. Effects of four types of commonly used fillers (asbestos floats, ground quartz, calcium silicate, and clay) on the heats of reaction of diallyl-o-phthalate prepolymers using t-butyl perbenzoate and dicumyl peroxide initiators show the large inhibiting effect of untreated kaolinite clays on this polymerization.     

Voltammetric behavior of tertiary butyl bromide at mercury electrodes in dimethylformamide

Polarograms for t-butyl bromide in dimethylformamide containing tetramethylammonium perchlorate exhibit two waves which signal stepwise reduction of the starting material to the t-butyl radical and the t-butyl carbanion. Cyclic voltammograms obtained with a hanging mercury drop and at a scan rate of 50 mV s^?1 confirm that the alkyl bromide undergoes stepwise reduction; but the height of the second peak is abnormally small, indicating that t-butyl radicals engage in combination and disproportionation. At a faster scan rate (500 mV s^?1), the first wave nearly merges with the second wave. At all scan rates, two pairs of anodic-cathodic waves, associated with reversible bromide-assisted oxidation of mercury, appear at positive potentials. In addition, another set of anodic-cathodic waves is seen if the potential is scanned rapidly to a value at which the t-butyl carbanion is generated; this set of waves might be related to the formation of trimethylammonium methylide (produced when the tetramethylammonium cation donates a proton to the t-butyl carbanion). Although this latter set of waves is eliminated by addition of a proton donor (diethyl malonate) to the system, the anion of diethyl malonate is itself involved in the appearance of yet another pair of anodic-cathodic waves.     

Oxygen-atom transfer from carbon dioxide to a Fischer carbene at (PNP)Ir

Dehydrogenation of the dihydride (PNP)IrH2 with norbornylene in the presence of t-butyl methyl ether leads to formation of an iridium(I) Fischer carbene complex, (PNP)Ir C(H)OtBu, by double C-H activation and loss of H2. The square planar pincer-type carbene effects quantitative oxygen-atom transfer from CO2 (1 atm) at ambient temperature to generate t-butyl formate and (PNP)Ir-CO. The iridium carbene reacts similarly with carbonyl sulfide and phenyl isocyanate, causing sulfur-atom and nitrene-group transfer, respectively. In the absence of a hydrogen acceptor, thermolysis of (PNP)IrH2 in t-butyl methyl ether under an atmosphere of CO2 also results in the formation of (PNP)Ir-CO and oxidation of t-butyl methyl ether to t-butyl formate via an iridium carbene. Preliminary mechanistic studies indicate that these reactions proceed through an intermediate four-membered metallalactone.     

叔丁基取代二苯并-18-冠-6的合成

以二甘醇和邻苯二酚为原料制得二苯并-18-冠-6;以多聚磷酸为催化剂和溶剂,将二苯并-18-冠-6与叔丁醇反应实现叔丁基化;利用正庚烷重结晶对叔丁基化反应产物进行纯化,得到4,4′-二叔丁基二苯并-18-冠-6和4,5′-二叔丁基二苯并-18-冠-6两种对称的二叔丁基二取代苯并冠醚产品.利用红外光谱和核磁共振谱表征了二叔丁基二取代苯并冠醚产物的结构。     

Stereoselective Synthesis of syn-and anti-3a-Hydroxyl-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b] indole-2-carboxylic Acid

The structure of syn-and anti-N^b-(p-toluenesulfonyl)-3a-hydroxyl-1,2,3,3a,8,8a-hexahydro pyrrolo[2,3,-b]indole-2-carboxylic t-butyl ester was stercoselectively synthesized by oxidative ring formation of N^b-(p-toluenesulfonyl)-L-tryptophan t-butyl ester in methylene chloride containing dimethyldioxirane(DMDO),the p-toluenesulfonly group and t-butyl group can be easily removed by sodium naphthalenide and trifluoroacetic acid,respectively.     

Reaction of carboxamide with Cu2Oisonitrile complex; formation of a new chelated copper(I) complex

Reaction of carboxamides with Cu₂O in the presence of t-butyl isocyanide gave new chelated copper(I) complexes, which probably are formed by the insertion of t-butyl isocyanide into the coppernitrogen bond of copper(I) amide isonitrile complexes, which were initially produced from the carboxamides and Cu₂Ot-butyl isocyanide complex. The same chelated copper(I) complexes were prepared more readily by the reaction of the corresponding N-trimethylsilyl-carboxamides with Cu₂Ot-butyl isocyanide complex. Reactions of the copper(I) complexes thus obtained with alkylating agents, such as alkyl halides, alkyl tosylates and triethyloxonium tetrafluoroborate, also were described.     

All ring compounds—XXIX : Thermal decomposition of t-butyl per (trans-2-substituted cyclopropyl) acetates

Three kinds of t-butyl per (trans-2-substituted cyclopropyl) acetates (RH, CH₃, C₆H₅) were synthesized from the corresponding acyl chlorides and thermally decomposed in cyclohexane to investigate the chemical stability and behaviour of the cyclopropylcarbinyl radical. Clean first-order kinetics were obtained in all of the thermal decomposition reactions. The experimental fact that the decompositoin rates and activation parameters of these three t-butyl peresters are similar to each other may indicate the absence of the ionic character in the transition state suggesting the almost complete homolytic decomposition of these peresters. Although the typical concerted decomposition might be invalid for these peresters in view of the activation parameters, it would be suggested from the product studies that the decomposition of these peresters was characterized by a considerable loss of their acyl-alky] bonds at the time of the fission of their OO bonds. The products yielded from the thermal decomposition of t-butyl per (trans-2-phenylcyclopropyl) acetate in various hydrogen donating solvents consisted of three hydrocarbons and two t-butyl ethers. The formation of these t-butyl ethers, possibly cage products, was significant.     

Oxiranylidene intermediate in the reaction of trans-2-chloro-3- tert-butyloxirane with sodium phenoxide.

The reaction of trans-2-chloro-3-(t-butyl)oxirane with sodium phenoxide in acetonitrile to give trans-2-phenoxy-3-(t-butyl)oxirane involves α-elimination to give an oxiranylidene which undergoes a stereoselective stepwise addition of phenol to give product.     

叔丁基｛1-[(对苯乙酰基)苯基]环丁基｝氨基甲酸酯的合成

叔丁基[1-(对溴苯基)环丁基]氨基甲酸酯与N-甲基-N-甲氧基-苄酰胺在正丁基锂的作用下,经Weinreb酮合成法合成了抗癌药物二氮杂萘衍生物的关键中间体——叔丁基{1-[(对苯乙酰基)苯基]环丁基}氨基甲酸酯,收率33%,其结构经1H NMR确证。     

A facile formation of cyclic selenuranes and a cyclic selenurane oxide in the reaction of 2-methylseleno- and 2-phenylselenobenzoic acids and their derivatives with t-butyl hydroperoxide

The reaction of 2-methylselenobenzoic acid with 1,1′-carbonyldiimidazole followed by addition of t-butyl hydroperoxide gave cyclic selenuranes $\text{2a}$ and $\text{3a}$, suggesting the intramolecular insertion of the neighboring selenium atom into the OO bond of t-butyl 2-methylselenoperoxybenzoate. In the reaction of 2-phenylselenobenzoyl chloride with t-butyl hydroperoxide, cyclic selenurane $\text{2b}$ and the oxide $\text{7}$ were obtained.     

t-Butyl Chloromethyl Ether

A convenient preparation of t-butyl methylthiomethyl ether (2) and its conversion to t-butyl chloromethyl ether (1) are described. Methylthiomethanol (4), which was previously unknown, was isolated as a by-product from the preparation of (2): it is a stable distillable liquid.     

Deuterium kinetic isotope effects in microsolvated gas-phase E2 reactions: Methanol and ethanol as solvents

The gas-phase reactions of F(-)(CH(3)OH) and F(-)(C(2)H(5)OH) with t-butyl bromide have been investigated to explore the effect of the solvent on the E2 transition state. Kinetic isotope effects (KIEs) were measured using a flowing afterglow-selected ion flow tube (FA-SIFT) mass spectrometer upon deuteration of both the alkyl halide and the alcohol. Kinetic isotope effects are significantly more pronounced than those previously observed for similar reactions of F(-)(H(2)O) with t-butyl halides. KIEs for the reaction of F(-)(CH(3)OH) with t-butyl bromide are 2.10 upon deuteration of the neutral reagent and 0.74 upon deuteration of the solvent. KIEs for the reaction of F(-)(C(2)H(5)OH) with t-butyl bromide are 3.84 upon deuteration of the neutral reagent and 0.66 upon deuteration of the solvent. The magnitude of these effects is discussed in terms of transition-state looseness. Additionally, deuteration of the neutral regent and deuteration of the solvent do not produce completely separable isotope effects, which is likely due to a crowded transition state. These results are compared to our previous work on S(N)2 and E2 solvated systems.     

Deplacements bomolytiques intramoleculaires. 13 - additions radicalaires a des peroxydes de γ-alcenyle et de t-butyle : influence des substituants de la partie alcenyle sur la formation d'oxetannes substitues en 2

Free radical additions of ZH hydrogen donors to γ-unsaturated peroxides were studied; 4 or 5 membered oxacyclanes were obtained according to the substitution of the double bond. The adduct-peroxide was also obtained besides the heterocycle depending on the presence and the position of substituents. For this reason a synthetic application of this reaction of addition-elimination has been limited to 3-methyl but-3-enyl t-butyl peroxide and 4-methyl pent-4-enyl t-butyl peroxide.     

Reactions of t-butyl peresters—III Cuprous bromide-catalyzed reaction of peresters with ethers

Aliphatic and cyclic ethers react smoothly with t-butyl peracetate and t-butyl perbenzoate at 67–90° in the presence of cuprous bromide. The first products of this reaction are the acyloxy derivatives of the ethers, which are unstable under the chosen experimental conditions and decompose to the corresponding carboxylic acids and unsaturated ethers. Thus, 2,3-dihydrofuran was prepared from 2-benzoyloxytetrahydrofuran in a 66% yield. The unsaturated ethers add t-butyl alcohol to give the corresponding acetals, this step being catalyzed by the carboxylic acid. This reaction is general for ethers containing two adjacent methylene groups, such as n-propyl and n-butyl ethers, tetrahydrofuran, and tetrahydropyran. Diethers, such as 1,4-dioxane and 1,2-dimethoxyethane, give more stable benzoyloxy derivatives, which decompose slowly on prolonged heating to give the expected acetals in low yield.     

Eine einfache methode zur synthese von organosilylphosphinen

Trimethylchlorosilane reacts with di-(t-butyl)chlorophosphine, t-butyldichlorophosphine or PCl₃ and magnesium in hexametylphosphoric triamide under formation of trimethylsilyl-di-(t-butyl)phosphine, bis(trimethylsilyl)-t-butylphosphine or tris(trimethylsilyl)phosphine respectively in high yields. This method is also useful for the synthesis of organogermanium and organotin phosphines as well as of corresponding organometal arsines.     

Unusual and unexpected reactivity of t-butyl dicarbonate (Boc2O) with alcohols in the presence of magnesium perchlorate. A new and general route to t-butyl ethers

[reaction: see text] A new mild method for protecting alcohols as t-butyl ethers is reported. The reaction proceeds with Mg(ClO4)2 and Boc2O and shows general applicability. The deprotection of t-butyl ethers has also been revisited. Preliminary results indicate the CeCl3 x 7H2O/NaI system is a very suitable catalyst for their removal.     

哌啶类化合物和有机过氧化物体系引发甲基丙烯酸甲酯聚合的研究

本文研究了四种哌啶类环状脂肪胺哌啶(P)、2,2,6,6-四甲基-4-哌啶醇(TMP)、N-乙基哌啶(NEP)、1,2,2,6,6-五甲基-4-哌啶醇(PMP)分别与有机过氧化物过氧化苯甲酰(BPO)、过氧化月桂酰(LPO)、叔丁基过氧化氢(TBH)、过氧化笨甲酸叔丁酯(TBPB)组成的引发体系对甲基丙烯酸甲酯(MMA)聚合的影响。测定了聚合反应的表观活化能和动力学方程。     

Thio-organotin Antioxidants for Polypropylene: Reactivity towards t-Butyl Hydroperoxide

Various thio-organotin compounds have been reacted with t-butyl hydroperoxide in order to determine whether this oxidation can be responsible for the stabilizing capacity of some thio-organotins towards polyolefin degradation. The kinetics of t-butyl hydroperoxide disappearance, in the presence of thiotin compounds, shows different reactivity according to the structure of oranometallic reagent. Product analysis indicates organotin oxide, dialkyl disulfide and t-butanol as major reaction products. The reactivity sequence towards hydroperoxide is the same as the order observed for polypropylene stabilization.     

双硫碳阴离子与溴乙酸烷基酯的反应

双硫碳阴离子1是一个极为有用的合成原(Synthon),它在合成化学中已得到广泛应用。1通常与单官能团亲电试剂反应能产生满意的结果~([3a]),我们用此法从环氧乙烷成功地合成了化合物2a~([3b])。1与双官能团化合物的反应,例如与N,N-二乙基溴乙酰胺~([1b])或β-溴丙酸乙酯~([4])的反应均能得到溴被取代的产物,得率分别为50%和74%。这可能是由于酰氨羰基的不活泼性(前者)和β-溴丙酸酯的烯醇化使溴原子处于活泼的烯丙位(后者),从而有利于1进攻与溴相连的碳原子。本文报道1与滇乙酸烷基酯的反应以制备溴被取代的产物2b。1与溴乙酸叔丁酯反应,主要得到溴被取代的2-(3′-硫杂戊基)-2-叔丁氧甲酰甲基-1,3-二硫杂环己烷(3),得率70%;若与溴乙酸甲酯或乙酯反     

Anionic synthesis of in-chain 3° amine-functionalized polybutadienes

Anionic copolymerizations of butadiene (M₁) with excess 1-(4-dimethylaminophenyl)-1-phenylethylene (M₂) were conducted in benzene at room temperature for 24–48h using sec-butyllithium as initiator. Anisole, triethylamine and t-butyl methyl ether were added in ratios of [B]/[RLi] = 60, 20, 30, respectively, to promote copolymerization. Narrow molecular weight distribution copolymers with M̄n = 14 × 10³ to 32 × 10³ g/mol (M̄_w/M̄n =1.02–1.03) and 8,12 and 30 amine groups per chain for anisole, triethylamine and t-butyl methyl ether, respectively, were obtained. The butadiene monomer reactivity ratios (r1) were 42, 33 and 14 for anisole, triethylamine and t-butyl methyl ether, respectively.