Secondary hydroxyl groups

Used for phenols, amines, amino acids, amino phosphoric acids, saccharides, and vitamins Useful for the relatively straightforward acylation of hydroxyl groups, secondary or tertiary amines... 

The nature of the hydroxyl group secondary and tertiary alcohols are strongly g ycuroconjugated, approximately ten times better than that of the isomeric primary alcohols. This is evidenced by a very important contribution of site 4211.301 with respect to chain lengthening ,(0.30). 

The type of alcohol produced depends on the carbonyl compound Substituents present on the carbonyl group of an aldehyde or ketone stay there—they become sub stituents on the carbon that bears the hydroxyl group m the product Thus as shown m Table 14 3 (following page) formaldehyde reacts with Grignard reagents to yield pri mary alcohols aldehydes yield secondary alcohols and ketones yield tertiary alcohols... 

Although acetyl chloride is a convenient reagent for deterrnination of hydroxyl groups, spectroscopic methods have largely replaced this appHcation in organic chemical analysis. Acetyl chloride does form derivatives of phenols, uncompHcated by the presence of strong acid catalysts, however, and it finds some use in acetylating primary and secondary amines. 

Diester/Ether Diol of Tetrabromophthalic Anhydride. This material [77098-07-8] is prepared from TBPA in a two-step reaction. First TBPA reacts with diethylene glycol to produce an acid ester. The acid ester and propylene oxide then react to give a diester. The final product, a triol having two primary and one secondary hydroxyl group, is used exclusively as a flame retardant for rigid polyurethane foam (53,54). 

Chemical Properties. Trimethylpentanediol, with a primary and a secondary hydroxyl group, enters into reactions characteristic of other glycols. It reacts readily with various carboxyUc acids and diacids to form esters, diesters, and polyesters (40). Some organometaUic catalysts have proven satisfactory for these reactions, the most versatile being dibutyltin oxide. Several weak bases such as triethanolamine, potassium acetate, lithium acetate, and borax are effective as stabilizers for the glycol during synthesis (41). 

The biosynthesis process, which consists essentially of radical coupling reactions, sometimes followed by the addition of water, of primary, secondary, and phenohc hydroxyl groups to quinonemethide intermediates, leads to the formation of a three-dimensional polymer which lacks the regular and ordered repeating units found in other natural polymers such as cellulose and proteins. 

Structure Modification. Several types of stmctural defects or variants can occur which figure in adsorption and catalysis (/) surface defects due to termination of the crystal surface and hydrolysis of surface cations (2) stmctural defects due to imperfect stacking of the secondary units, which may result in blocked channels (J) ionic species, eg, OH , AIO 2, Na", SiO , may be left stranded in the stmcture during synthesis (4) the cation form, acting as the salt of a weak acid, hydrolyzes in aqueous suspension to produce free hydroxide and cations in solution and (5) hydroxyl groups in place of metal cations may be introduced by ammonium ion exchange, followed by thermal deammoniation. 

Chemical properties of isopropyl alcohol are determined by its functional hydroxyl group in the secondary position. Except for the production of acetone, most isopropyl alcohol chemistry involves the introduction of the isopropyl or isopropoxy group into other organic molecules by the breaking of the C—OH or the O—H bond in the isopropyl alcohol molecule. 

Ammonia, and Amines. Isopropanolamine is the product of propylene oxide and ammonia ia the presence of water (see Alkanolamines). Propylene oxide reacts with isopropanolamine or other primary or secondary amines to produce A/- and A/,A/-disubstituted isopropanolamines. Propylene oxide further reacts with the hydroxyl group of the alkanolamines to form polyether polyol derivatives of tertiary amines (50), or of secondary amines ia the presence of a strong base catalyst (51). 

The amide nitrogen readily adds across the carbonyl group of an aldehyde yielding N-hydroxyalkyl-substituted pyrrohdinones (68), eg, A/-methylol-2-pyrrohdinone [15438-71-8] (34). In the presence of secondary amines or alcohols, the hydroxyl groups are replaced (69), eg, if diethylamine is present the product is A/-diethylaminomethyl-2-pyrrohdinone [66297-50-5] (35). 

The polyaddition reaction is influenced by the stmcture and functionaHty of the monomers, including the location of substituents in proximity to the reactive isocyanate group (steric hindrance) and the nature of the hydroxyl group (primary or secondary). Impurities also influence the reactivity of the system for example, acid impurities in PMDI require partial neutralization or larger amounts of the basic catalysts. The acidity in PMDI can be reduced by heat or epoxy treatment, which is best conducted in the plant. Addition of small amounts of carboxyHc acid chlorides lowers the reactivity of PMDI or stabilizes isocyanate terrninated prepolymers. 

Compounds with amino or hydroxyl groups decrease in biodegradabihty relative to degree of saturation, in the following order primary, secondary, then tertiary carbon atom of attachment. 

Most carbohydrates have two kinds of reactive groups the carbonyl group and primary and secondary hydroxyl groups. 

Hydroxyl Group. The OH group of cyanohydrins is subject to displacement with other electronegative groups. Cyanohydrins react with ammonia to yield amino nitriles. This is a step in the Strecker synthesis of amino acids. A one-step synthesis of a-amino acids involves treatment of cyanohydrins with ammonia and ammonium carbonate under pressure. Thus acetone cyanohydrin, when heated at 160°C with ammonia and ammonium carbonate for 6 h, gives a-aminoisobutyric acid [62-57-7] in 86% yield (7). Primary and secondary amines can also be used to displace the hydroxyl group to obtain A/-substituted and Ai,A/-disubstituted a-amino nitriles. The Strecker synthesis can also be appHed to aromatic ketones. Similarly, hydrazine reacts with two molecules of cyanohydrin to give the disubstituted hydrazine. 

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