85535-35-9

Upstream product

• 73838-69-4 9-tert-butylfluorenide anion 
• 100-44-7 benzyl chloride 
• 106358-48-9 potassium salt of 9-tert-butylfluorene 

Relevant academic research and scientific papers

Systematic ranking of nucleophiles as electron donors

A systematic ranking of different nucleophiles (including enolates, phenolates, thiophenolates, hydroxide, cyanide) with respect to their ability to stabilise the transition state of substitution reactions has been carried out in acetonitrile and dimethyl sulfoxide. The method is based on a comparison of the rate constant, kSUB, for the substitution reaction between a given nucleophile and benzyl chloride with the rate constant, kET, for the corresponding electron transfer from an aromatic radical anion to benzyl chloride. The ratio kSUB/kET expresses the rate enhancement due to electronic interaction in the transition state, ΔGSta, of the substitution reaction. In this study, kSUB/kET ratios between 5 and 1031 were determined corresponding to ΔGSta-values of 4-175 kJ mol-1. These values cover substitution reactions going from outer-sphere electron transfer to SN2 with partial bond formation in the transition state. The kSUB/kET values are found to be largest for nucleophiles such as OH- and CN- with very poor electron-donating abilities (high oxidation potentials). When different types of nucleophile with similar oxidation potentials are compared, a decrease in kSUB/kET is observed going from sulfur-to carbon- and further to oxygen-centred nucleophiles. The ranking of nucleophiles in reactions involving electrophiles other than benzyl chloride is discussed with emphasis on steric hindrance and electronic effects.

The Role of Single-Electron Transfer in SN2-Type Substitution Reactions of Anions with Alkyl Halides

Rate constants (kobsd) for reactions of electrophiles with: (a) various carbanions, including 9-substituted fluorenide ions (9-GFl-), 9-substituted xanthenide ions, α-cyano carbanions, anb β-diketo enolate ions, (b) phenothiazinide (PTZ-) and carbazole (Cb-) nitranions, (c) 4-substituted phenoxide ions, and (d) thiphenoxide ions, have been campared with rate constants for single-electron transfer (kSET) calculated using a Marcus-type equation.For both 9-GFl- carbanion and 2-GPTZ- nitranion families reacting with SET acceptors, such as 1,1-dinitrocyclohexane, the kobsd/kSET ratio is near unity.For 9-GFl- carbanions reacting with Ph2CHCl the kobsd/kSET ratios range from 2 to 105, those for 2-PTZ- nitranions from 370 to 1.3*104, and those for Cb- nitranions from 108 to 1010.For reactions of 4-GC6H4O- oxanions with Ph2CHCl the ratios range from 103 for G = Me2N to 1013 for G = CN; for PhS- ion reacting with n-BuBr the ratio is 1017.The significance of these results with respect to the role of an outer sphere SET mechanism in substitution reactions of anions with alkyl halides is discussed.

Reactions of 9-Substituted Fluorenide Carbanions with Allyl Chlorides by SN2 and SN2' Mechanism

The average ratio of SN2 rate constants for benzyl chloride vs. allyl chloride reacting with 9-substituted fluorenide carbanions, 9-G-Fl- (G = Me, PhS, Ph o-tol, or t-Bu), in Me2SO solution is 2.3, which is close to the ratio previously observed for reactions of smaller nucleophiles with more localized charges, such as iodide ion, in various solvents.Broensted plots of log k vs. pKHA (both in Me2SO) are used to calculate reactivity values (r) for 9-G-Fl- ions of the same basicity reacting with allyl chloride.The r values reveal the same order of steric effects for G in these SN2 reactions as was found previously for benzyl chloride, i.e., Me - ions were found to increase progressively and appreciably with γ-methyl substitution, i.e., CH2=CHCH2Cl (1) , MeCH=CHCH2Cl (4) , Me2C=CHCH2Cl (5), whereas the Broensted β values decreased progressively.The second-order rate constants for reactions with families of 9-G-Fl- ions were found to follow a somewhat different pattern for α-methyl substitution, i.e., CH2=CHCH2Cl (1) > CH2=CHCH(Me)Cl (2) CH2=CHC(Me)2Cl (3); the rate differences were small, but the β values again decreased progressively.Product studies indicated that 1 reacts with 9-G-Fl- ions by an SN2 mechanism but that 2 gives SN2' products in a amounts increasing along the series G = Me, Ph, o-tol, t-Bu; 3 appears to give only SN2' products.The rates of reactions of 9-CN-Fl- and 9-CO2MeFl- ions with 3 to form SN2' and SN2 products are independent of the carbanion concentration.The first-order reaction of 9-CN-Fl- ion with t-BuCl in MeOH gives 17percent yield of 9-CN-9-t-BuFl.Entalpies of activation for SN2 reactions of 9-G-Fl- ions reacting with 5 are 7-9 kcal/mol lower, and entropies of activation are 18, or more, eu units less positive than for SN2' reactions of 9-G-Fl- ions with 3.Mechanism for SN2' reactions are discussed in light of these findings.

Steric and Electronic Effects in SN2 reactions of 9-Substituted Fluorenyl and α-Cyano Carbanions with Benzyl Chloride in Dimethyl Sulfoxide Solution

Rates of reactions of PhCH2Cl with carbanions derived from six α-cyano carbon acids of varied structure with pKa values ranging over 16 units have been measured.When placed on a log k vs. pKa plot the points fit near to the extended

A Direct Relationship between Nucleophilicity and Basicity in SN2 Reactions of Fluorenyl Anions with Benzyl Chloride in Dimethyl Sulfoxide Solution

The rates of reactions for nine 9-substituted fluorenyl anions, 9-G-Fl- (G=CN, CO2Me, PhSO2, PhS, Ph, PhO, PhCH2, Me, t-Bu), reacting with benzyl chloride in Me2SO solution have been measured.For 9-CN-Fl- the rates increased with sol