摘要:
A cement admixture comprised of a mixture of certain alkyl ether oxyalkylene adducts with certain oxyalkylene glycols to provide cement compositions of mortar and concrete which inhibit drying shrinkage while permitting substantial air entrainment and enhanced compressive strength.
摘要:
A selective process for the preparation of diphenylmethane bis(dialkylureas) is disclosed. An alkyl phenylcarbamate or an N,N-dialkyl-N'-phenylurea is reacted with a methylene bis(alkyl carbamate) in the presence of an acid catalyst. The use of a staged addition of phenylcarbamate or phenylurea to the methylene bis(carbamate) and the use of a ramped temperature program are the keys to good selectivity to MDI dimer products.
摘要:
An improved process is provided for the preparation of aromatic mono- and poly- isocyanates by the thermal decomposition of an aromatic bis dialkyl urea in solvent in the presence of a tertiary amine hydrohalide, such as pyridine hydrochloride, as a promoter for conversion of the urea groups to isocyanates.
摘要:
The invention relates to a cement composition containing a shrinkage reducing amount of an alkyl ether derivative of an aliphatic polyhydroxy compound of the formula:Q--[(A).sub.n --OR].sub.xwherein Q is a C.sub.3 -C.sub.12 aliphatic hydrocarbon group, R is hydrogen or C.sub.1 -C.sub.10 alkyl, at least one R being the C.sub.1 -C.sub.10 alkyl group, A is C.sub.2 -C.sub.4 oxyalkylene, n is 0-10, and x is 3-5.
摘要:
A process for preparing trisubstituted ureas is disclosed. A nitroarene is reacted with carbon monoxide and a secondary amine in the presence of a Group VIII transition metal catalyst and optionally one or more promoters selected from primary amines, halide ion-containing compounds, and chelating phosphorus and nitrogen compounds.
摘要:
A process for recovering both an amine and a volatile acid from an amine salt is disclosed. In the process, the amine salt is reacted with a non-volatile acid to liberate the volatile acid. Thermal decomposition of the resulting amine/non-volatile acid salt liberates the amine.
摘要:
An improved process is provided for the preparation of aromatic mono- and poly-isocyanates by the thermal decomposition of an aromatic bis dialkyl urea in solvent in the presence of an organic sulfonic acid or sulfonated aromatic ion exchange resin as a promoter for conversion of the urea groups to isocyanates.
摘要:
An improved process is provided for the preparation of methylene diphenylene diisocyanates (MDI) and polymethylene polyphenylene poly (diisocyanates) by the thermal decomposition of a methylene diphenylene bis (dialkylurea) or a polymethylene polyphenylene poly (dialkylurea) in a solvent in the presence of a tertiary amine hydrohalide, such as pyridine hydrochloride, as a promoter for conversion of the urea groups to the corresponding isocyanate.
摘要:
Polyethers of polyhydric compounds are prepared by the liquid phase reaction of polyhydric compound and the reaction being carried out with separate liquid phases comprised of a polar polyhydric compound phase and an organic polyether containing phase.
摘要:
A selective process for the preparation of diphenylmethane diisocyanate precursors is disclosed. An alkyl phenylcarbamate or an N,N-dialkyl-N'-phenylurea is reacted with a methylene bis(alkyl carbamate) in the presence of an acid catalyst. The use of a staged addition of phenylcarbamate or phenylurea to the methylene bis(carbamate) and the use of a ramped temperature program are the keys to good selectivity to MDI dimer products.