Investigation into the Semantic Density and Semantic Gravity Wave Profile of Teachers When Discussing Electrophilic Aromatic Substitution (SEAr).

Language in chemistry is highly specialized, and for students, transitions in language complexity from high school to university can be extremely challenging. With an increasingly diverse cohort of students enrolled in UK chemistry degree programs, better understanding the linguistic challenges students face is becoming a greater pedagogical priority. Spoken language plays a central role when learning chemistry, and any misunderstandings can lead to misconceptions that can impede students' success in this demanding subject. This small-scale study sought to compare the complexity of spoken-language explanations of the same chemical process within UK secondary (high school) and university contexts. The study involved seven organic chemistry educators/teachers, four based in a UK university and three in a UK high school, discussing electrophilic aromatic substitution (SEAr) via a lecture or screencast. The participants' spoken discourse was transcribed and coded according to the concepts of semantic gravity (the degree to which meaning relates to context) and semantic density (the degree to which meaning is condensed within symbols) drawn from Legitimation Code Theory, and then it was analyzed for semantic waves. When considering semantic gravity, there were some similarities and some differences. In all cases, semantic gravity was weaker, but participants based in a university environment generally tended to exhibit relatively weaker semantic gravity than their school-based counterparts. The school-based participants usually added further explanations to clarify what was meant during an explanation and exhibited semantic waves by unpacking and repacking a concept, whereas the university-based participants tended to show a flatter semantic profile. Findings showed that, across the levels of study investigated, semantic density was stronger: a similar complexity of chemistry-specific vocabulary used by all seven participants, regardless of the audience. Findings have pedagogical implications and suggest that a larger-scale study of semantic waves in oral chemistry discourse could usefully inform specific-purposes language teaching.

Flow synthesis using gaseous ammonia in a Teflon AF-2400 tube-in-tube reactor: Paal-Knorr pyrrole formation and gas concentration measurement by inline flow titration.

Using a simple and accessible Teflon AF-2400 based tube-in-tube reactor, a series of pyrroles were synthesised in flow using the Paal-Knorr reaction of 1,4-diketones with gaseous ammonia. An inline flow titration technique allowed measurement of the ammonia concentration and its relationship to residence time and temperature.

Total synthesis of chloptosin: a dimeric cyclohexapeptide.

Here we describe in full our investigations into the synthesis of the dimeric cyclohexapeptide chloptosin in 17 linear steps. Particularly, this work features an organocatalytic tandem process for the synthesis of the embedded piperazic acids, in which a differentially protected azodicarboxylate is used together with pyrrolidinyl tetrazole as the catalyst. The central biaryl bond is being formed by Stille coupling of two sterically demanding ortho-chloropyrroloindole fragments. The inherent flexibility of the synthetic strategy proved beneficial as the route could be adjusted smoothly during the progression of the synthesis programme.

Tripodal molecules for the promotion of phosphoester hydrolysis.

A series of low molecular weight tripodal amide/histidine-containing compounds (1-2) have been synthesised and shown to increase the rate of bis-(p-nitrophenyl) phosphate (BNPP) and soman (GD) breakdown in buffered aqueous solution.

Anion recognition and transport properties of sulfamide-, phosphoric triamide- and thiophosphoric triamide-based receptors.

Studies of sulfamide, phosphoric triamide and thiophosphoric triamide-based organocatalysts show that the phosphorus containing systems are effective new hydrogen bonding motifs for the recognition and transport of anions.