Alcohols, aromatic secondary

Aliphatic secondary alcohol — Aromatic secondary alcohol — Cyclic equatorial sec. alcohol ... 

Interestingly, free nano-iron oxide particles are active catalysts for the selective oxidation of alcohols to yield the corresponding aldehydes/ketones [72, 73]. Different aromatic alcohols and secondary aliphatic alcohols were oxidized with high selectivity, but at low conversion. Here, further improvement should be possible (Scheme 25). 

In the absence of primary alcohols, secondary alcohols participate in transesterification reactions to provide good yields for most alcohols. No significant electronic effect is observed when electron-releasing and electron-withdrawing substitutents on aromatic secondary alcohols (Table 22, entries 2-4). A steric effect is observed with cyclohexanol derivatives. Increasing the a-substituent from hydrogen to methyl or teri-butyl dramatically decreases efficiency of transesterifi-... 

The addition of amines and ethers to alkyllithium compounds profoundly affects polymerization of such species. Amines and ethers alter the association of RLi compounds and change the course of the polymerization and its kinetics. Also, the presence of small amounts of such impurities as water, alcohols, or a-acetylenes, influences the kinetic chain length. The chain-termination reaction with such acidic protons is almost instantaneous. However, there are certain types of protons, such as a-aromatic, secondary amine, and /3-acetylenic, that are not acidic enough to react immediately but will undergo transmetalation during the course of a polymerization reaction. This results in termination or chain transfer of the polymer chain, and limits the realization of polymers of... 

Catalytic Enantioselective Alkylation of Aldehydes with Dialkylzincs . The chiral M,M-dialkylnorephedrines, analogs of (1), are highly efficient catalysts for the enantioselective addition of dialkylzincs to aliphatic and aromatic aldehydes. Optically active aliphatic and aromatic secondary alcohols with high ee are obtained using N,fV-dialkylnorephedrines (4-6 mol%) as chiral catalyst precursors. When (lS,2/J)-MN-dialkylnorephedrine is used as a chiral catalyst precursor, prochi ral aldehydes are attacked at the si face to afford (S)-alcohols (when the priority order is R >R2)(eq7). 

Secondary alcohols having a C—OH stretching vibration that absorbs in the range cited for primary alcohols alpha, beta- unsaturated secondary alcohols C-OH stretching, 1074-1012 cnv1 alpha-chloro or bromo secondary alcohols C-OH stretching, near 1050 cnv1 Aromatic secondary alcohols... 

A similar but slightly less efficient catalyst system was developed by Yang et al. (Scheme 7.29). The (J )-BINOL-functionalised mesoporous silica 56 was prepared and tested in the reactions described above. A wide range of chiral aromatic secondary alcohols were obtained with good to high enantio-selectivities (up to 93% enantiomeric excess) and the ligand was also recycled. 

Alcohols are compounds that contain -OH groups connected to an alkyl carbon. Phenols are similar, but have an -OH group connected directly to an aromatic ring. The terms primary, secondary, and tertiary are used to describe aicohois. in a primary alcohol, a carbon can be connected to one or no other carbon atoms example CH3-OH, methyl alcohol. A secondary is connected to two carbons example isopropyl alcohol. Tertiary describes connections to three other carbons example tert-butyl alcohol (Figure 19-7). 

Various aliphatic and aromatic secondary alcohols can be oxidized with peracetic acid in the presence of RUCI3 catalyst to give the corresponding ketones highly efficiently [75]. 

Aliphatic amines aromatic amines primary alcohols water secondary alcohols tertiary alcohols phenols carboxylic acids ureas amides urethanes. 

Scheme 2.9 Reaction of a,p-unsaturated aldehydes with aromatic secondary alcohols catalysed by a combination of a chiral quinidine and a chiral phosphoric acid.

This reaction is not suitable for the detection of secondary OH groups in the presence of primary hydroxyls, because small amounts of primary iodide prevent the pseudonitrole reaction. The nitrole reaction, on the other hand, is not disturbed by the presence of secondary hydroxy groups. This is the reason this test is reliable for the detection of primary alcohols, while for secondary alcohols it is of value only in the absence of primary alcohols. Aromatic alcohols (benzyl alcohol) do not give the nitrole reaction. While the nitrole reaction is positive with alcohols up to the pseudonitrole reaction cannot be used for alcohols above C5. 

The lipase PS from Burkholderia cepacia was supported on a Kynol ACC 507-15 active carbon cloth with and without modification by IL phase for the kinetic resolution (KR) of aromatic secondary alcohols with vinyl acetate. Scheme 2.30 [124]. For the asymmetric acylation of 1-phenylethanol, the conversion was about 50% using the ACC-supported [EMIm][NTf2] containing the enzyme. If other supports such as active carbon and alumina were used, the conversion of 1-phenylethanol was <10% even when a higher catalyst loading was employed. By applying optimized reaction conditions, the conversions of l-(furan-2-yl) ethanol and N-(2-hydroxy-2-phenylethyl) propionamide in the acylation reactions were 30-50% with 86-99% ee, respectively. 

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