Extensive observations of acetamide (CH 3 CONH 2 ) and formamide (NH 2 CHO) have been conducted toward Sgr B2(N) at 1, 2, and 3 mm using the Submillimeter Telescope (SMT) and the 12 m antenna of the Arizona Radio Observatory. Over the frequency range 65-280 GHz, 132 transitions of acetamide have been observed as individual, distinguishable features, although in some cases they are partially blended. The unblended transitions in acetamide indicate V LSR = 63.2 ± 2.8 km s −1 and ΔV 1/2 = 12.5 ± 2.9 km s −1 , line parameters that are very similar to that of formamide (NH 2 CHO) and other organic species in Sgr B2(N). For formamide, 79 individual transitions were identified over the same frequency region. Rotational diagram analyses indicate the presence of two components for both species in Sgr B2(N). For acetamide, the colder component (E u < 40 K) exhibits a rotational temperature of T rot = 17 ± 4 K and a column density of N tot = 5.2 ± 3.5 × 10 13 cm −2 ; the higher energy component has T rot = 171 ± 4 K and N tot = 6.4 ± 4.7 × 10 14 cm −2 . In the case of formamide, T rot = 26 ± 4 K and N tot = 1.6 ± 0.7 × 10 14 cm −2 for the colder component with T rot = 134 ± 17 K and N tot = 4.0 ± 1.2 × 10 14 cm −2 for the warmer region. The fractional abundances of acetamide are f (H 2 ) = 1.7 × 10 −11 and 2.1 × 10 −10 for the cold and warm components, and in formamide, f (H 2 ) = 5.3 × 10 −11 and 1.3 × 10 −10 . The similarity between the abundances and distributions of CH 3 CONH 2 and NH 2 CHO suggests a synthetic connection. The abundance of acetamide, moreover, is only a factor of three lower than that of formaldehyde, and very similar to acetaldehyde and ketene. CH 3 CONH 2 is therefore one of the most abundant complex organic species in Sgr B2(N), and could be a possible source of larger peptide molecules, as opposed to amino acids.

A new interstellar molecule, CH 3 NCO (methyl isocyanate), has been detected using the 12 m telescope of the Arizona Radio Observatory (ARO). CH 3 NCO was identified in spectra covering 48 GHz (68-116 GHz) in the 3 mm segment of a broadband survey of Sgr B2(N).Thirty very favorable rotational lines (K a = 0 and K a = 1 only; E u < 60 K) originating in five consecutive transitions (J = 8 → 7, 9 → 8, 10 → 9, 11 → 10, and 12 → 11) in both the A and E internal rotation species are present in this frequency range. Emission was observed at all of the predicted frequencies, with seventeen lines appearing as distinct, uncontaminated spectral features, clearly showing the classic a-type, asymmetric top pattern, with T R * ≈ 20-70 mK. The CH 3 NCO spectra also appear to exhibit two velocities components near V LSR ≈ 62 and 73 km s -1 , both with ΔV 1/2 ≈ 10 km s -1 -typical of molecules such as CH 2 CHCN, HNCO, and HCOOCH 3 in Sgr B2(N) . The column density of CH 3 NCO in Sgr B2(N) was determined to be N tot ≈ 2.3 × 10 13 cm -2 and 1.5 × 10 13 cm -2 for the 62 and 73 km s -1 components, corresponding to fractional abundances, relative to H 2 , of f ≈ 7.6 × 10 -12 and 5.0 × 10 -12 , respectively. CH 3 NCO was recently detected in volatized material from comet 67P/Churyumov-Gerasimenko by Rosetta's Philae lander, with an abundance ~1.3% of water; in Sgr B2(N), CH 3 NCO is roughly ~0.04% of the H 2 O abundance.Subject Headings: Astrochemistry ---ISM: molecules ---line: identification ---methods:laboratory : molecular ---molecular data ---comets: individual (67P/Churyumov-Gerasimenko)

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Millimeter-wave observations of PN, CP, and HCP have been carried out toward circumstellar envelopes of evolved stars using the Arizona Radio Observatory (ARO). HCP and PN have been identified in the carbon-rich source CRL 2688 via observations at 1 mm using the Submillimeter Telescope (SMT) and 2Y3 mm with the Kitt Peak 12 m. An identical set of measurements were carried out toward IRC +10216, as well as observations of CP at 1 mm. PN was also observed toward VY Canis Majoris (VY CMa), an oxygen-rich supergiant star. The PN and HCP line profiles in CRL 2688 and IRC +10216 are roughly flat topped, indicating unresolved, optically thin emission; CP, in contrast, has a distinct ''U'' shape in IRC +10216. Modeling of the line profiles suggests abundances, relative to H 2 , of f (PN) $ 3Y5 ð Þ ; 10 À9 and f (HCP) $ 2 ; 10 À7 in CRL 2688, about an order of magnitude higher than in IRC +10216. In VY CMa, f (PN) is $4 ; 10 À8. The data in CRL 2688 and IRC +10216 are consistent with LTE formation of HCP and PN in the inner envelope, as predicted by theoretical calculations, with CP a photodissociation product at larger radii. The observed abundance of PN in VY CMa is a factor of 100 higher than LTE predictions. In IRC +10216, the chemistry of HCP/CP mimics that of HCN/CN and suggests an N 2 abundance of f $ 1 ; 10 À7. The chemistry of phosphorus appears active in both carbon-and oxygen-rich envelopes of evolved stars.